Toro 38409, 38412, 38413, 38414, 38417 Service Manual

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R-TEK/DURAFORCE (E) ENGINE SERVICE MANUAL

Table of Contents – Page 1 of 1

PREFACE SAFETY SPECIFICATIONS SPECIAL TOOLS TROUBLESHOOTING MAINTENANCE CARBURETOR FUEL SYSTEM IGNITION SYSTEM REWIND STARTER ENGINE PIVOTING ZONE START BRAKE ELECTRIC START SYSTEM (120 VOLT) ELECTRIC START SYSTEM (12 VOLT)

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PREFACE

ABOUT THIS MANUAL

This manual was written expressly for the E series engines. There are two engines in this series. One is piston ported (R tek) and the other is a reed valve (DuraForce). As these en covered here. Where there are differences between the two versions, a headin discussed. We have made every effort to make this information complete and correct.

We hope that you find this manual a valuable addition to your service shop. If you have questions or comments re

arding this manual, please contact us at the following address:

The Toro Company Consumer Service Department 8111 Lyndale Ave. So. Minneapolis, MN 55420-1196

ines are of the same family, they will both be

will state which engine is being

The Toro Company reserves the ri

ht to change product specifications or this manual without notice.

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TABLE OF CONTENTS

SAFETY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

ine Specifications (All dimensions are for a new engine) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2

En En

ine Fastener Torque Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Standard Torques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

Carburetor Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

SPECIAL TOOL REQUIREMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6

ine Will Not Start When “Cold” . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

ine Will Start When “Cold”, But Not When “Hot” . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6

ine Will Not Produce Spark . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

ine Flooded With Fuel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

ine Has Low Compression . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

ine Lacks Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

ine Surges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

ine Backfires . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

ine Overheats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

ine Vibrates Excessively . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

ine Crankshaft Will Not Turn . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

ine Produces Mechanical Knocking Sound . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

ine Pre-Ignites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10

ine Smokes Excessively (Smoke is light colored, engine runs well) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10

ine Smokes Excessively (Smoke is dark, engine runs poorly) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10

ine Stalls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11

Spark Plu

MAINTENANCE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13

Fouled . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11

Recommended Maintenance Schedule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13

Air Filter (Mower Only) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14

Spark Plu Cleanin Cleanin Reassemblin

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14

the Exhaust System (Lawn Mower) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15

the Exhaust System (Snowthrower) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16

Exhaust System (Mower Only) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16

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TABLE OF CONTENTS

CARBURETOR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17

Theory of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17

Troubleshootin

Preliminary Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19

Removal of DuraForce Carburetor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20

Removal of R tek Carburetor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20

Disassembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21

Cleanin

Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23

Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25

Governor Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26

FUEL SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29

Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29

Fuel Cap Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29

and Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23

Reed Valve En Piston Ported En Presettin Servicin

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18

ine (DuraForce Engines Only) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26

ine (R tek Engines Only) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26

the Governor (DuraForce Engines Only) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

the Air Filter (DuraForce Engines Only) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27

Cleanin

IGNITION SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31

Troubleshootin Testin Spark Plu Spark Plu

CD Pack Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32

CD Pack Air Gap Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33

CD Pack Removal/Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33

Flywheel Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34

Flywheel Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34

Flywheel Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31

Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31

Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32

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REWIND STARTER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37

Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37

Removal and Disassembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37

Reassembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37

ENGINE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39

General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39

Theory of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39

Reed Valve En Piston Ported En

Both Piston Ported and Reed Valve En

Service Tips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41

Disassembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41

Inspection and Repair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42

Reed Valve Service (DuraForce En

Reassembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44

Reinstalling External Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45

Crankshaft Seal Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .46

PIVOTING ZONE START BRAKE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .47

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .47

Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .47

Disassembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48

Assembly. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

ine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39

ine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40

ines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40

ines Only) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43

ELECTRIC START SYSTEM (120 VOLT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .51

Troubleshootin

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .51

Starter Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Starter Disassembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52

Starter Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52

Starter Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .51

iii

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ELECTRIC START SYSTEM (12 VOLT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53

Troubleshootin

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53

Starter Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53

Starter Testin

Starter Disassembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .54

Starter Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .55

Starter Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .55

Alternator Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .56

Alternator Output Testin

Alternator Air Gap Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .57

Alternator Resistance Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .57

Cup Assembly Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .57

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .54

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .57

Page 8

SAFETY

SAFETY INFORMATION

General

This safety symbol means WARNING or PERSONAL SAFETY INSTRUCTION - read the instruction because it has to do with your safety. Failure to comply with the instruction may result in personal injury or even death.

This manual is intended as a service and repair manual only. The safety instructions provided herein are for troubleshootin information on the complete product powered by the E series en instructions are available throu

Lawn-Boy Corporation / The Toro Company Parts Department 8111 Lyndale Avenue South Bloomin

, service, and repair of the engine only. The individual Operator’s manual will contain safety

ine. Operator’s manuals with complete

ton, MN 55420 U.S.A.

Safety Tips

Avoid unexpected starting of engine...

Always turn off the powered product and disconnect the spark plu or repair.

Avoid lacerations and amputations...

Stay clear of all movin runnin movin potential to start.

Avoid burns...

.Do not touch the en after it has been runnin

Avoid Falls...

Do not operate the powered product on slippery surfaces or if footin

Avoid fires...

Wipe up any spilled fuel or oil immediately.

Avoid asphyxiation...

Never operate an en proper ventilation.

wire before attempting cleaning, adjustment,

parts whenever the engine is

. Treat all normally moving parts as if they were

whenever the engine is running or has the

ine while it is running or shortly

is questionable.

ine in a confined area without

Avoid accidental misuse of fuel...

Always store fuel in a properly labeled container desi

ned for gasoline.

Avoid injury due to inferior parts...

Use only Toro/Lawn-Boy ori important safety criteria are met.

Avoid injury to bystanders...

Always clear the area of bystanders before startin testin

powered equipment.

Avoid injury due to projectiles...

Always clear the area of sticks, rocks, or any other debris that could be picked up and thrown by the powered equipment. Keep all safety shields in place.

Avoid modifications...

Never alter or modify any part unless it is a factory approved procedure.

Avoid unsafe operation...

Always test the safety systems after makin adjustments or repairs on the machine.

inal parts to ensure that

Avoid fires and explosions...

Use a container desi fuel and never smoke while workin fuel.

ned for gasoline. Avoid spilling

with any type of

Page 9

SPECIFICATIONS

Specifications

Engine Specifications (All dimensions are for a new engine)

Item DuraForce R tek

Type Reed valve 2-cycle Piston ported 2-cycle

Bore

Stroke

Wrist pin diameter

Crankpin diameter

End play (crankshaft)

Side play (crankshaft) near lower main

Piston cyl. Clearance (tightest loc.)

Wrist pin hole diameter

Bottom ring thickness, new

End gap, new (both rings)

Displacement

2.5000" +

.5000" + .0000 - .0002 (12.70mm + .000 - .005)

.7427" + .0003 - .0002 (18.85mm + .008 - .005)

0 - .017" (0 - .431mm) Walk mower

.0006" + .0003 - .0006 (.015mm + .008 - .015)

.0035" to .0059" (.089 to .150mm)

.500"/.5005" (12.705mm / 12.712mm)

.0600 +

.0005 (63.5mm + .0127)

1.75" (44.45mm)

0 - .017" (0 - .431mm) 1998 Snow 0 - .0215" (0 - .533mm) 1999 and later Snow

.0005 (1.52mm + .013)

.016/.008 in. (.40/.20mm)

8.6 cu in. (141cc)

Horsepower 6.5HP 4 or 5HP

Compression ratio

Compression

Carburetor

Approximately 115 psi. Service limit 80 psi.

Dual-circuit Lawn-Boy with fixed jets, float type with primer and choke

5.8:1

Fuel required

Unleaded regular (87 octane R+M/2):2-cycle oil

Mix ratio 32:1 50:1 Recommended Oil .Lawn-Boy Generation II 2-cycle

oil or NMMA TCW3 Toro 2-cycle oil or NMMA TCW3

Fuel tank capacity

Ignition type

CD Pack air gap

Spark plug / air gap

Solid-state CD Pack, magneto type

NGK projected nose / NGK BPMR4A .030" (.76mm)

Varies with product

.010" (.25mm)

Start system Rope rewind or 12 VDC Rope rewind or 120 VAC

Governor

Governed Engine Speed

2900 +

300 rpm

Air vane

4HP runs at 3700 + CCR 2400 - 3700 5HP runs at 3800 + CCR 2450 & 2500 - 3800 rpm

CCR 3600 - 3900 rpm CCR 3650 - 4000 rpm Snow Commander - 4000 rpm All snow engines are +

300

300 rpm

Idle Speed 2200 - 2800 rpm N/A

ir Cleaner .Oiled foam type with Centrifugal

pre-cleaner N/A

Page 10

SPECIFICATIONS

Item DuraForce R tek

Choke Manual, butterfly type Fuel filter In-tank and in-carburetor Piston rin

Piston Permanent mold, hi

s Cast iron, semi-keystone top ring. Second ring is rectangular.

Anti-rotation pin in piston.

h silicon aluminum

Engine Fastener Torque Requirements

Item DuraForce R tek

Bolt, Head 140 - 200 in. lbs. (16 - 22 Nm) 140 - 200 in. lbs. (16 - 22 Nm) Jet, Main 4 - 6 in. lbs. (.44 - .66 Nm) 4 - 6 in. lbs. (.44 - .66 Nm) Jet, Pilot* 10 - 12 in. lbs. (1.1 - 1.3 Nm) 6 - 8 in. lbs. (.66 - .88 Nm)* Nozzle, Carburetor* 16 - 28 in. lbs. (1.7- 4.0 Nm) 20 - 30 in. lbs. (2.2 - 3.4 Nm) Nut, Blade 45 - 50 ft. in. (60 - 67 Nm) NA Nut, Flywheel 375 - 425 in. lbs. (42 - 47 Nm) 375 - 425 in. lbs. (42 - 47 Nm) Seat, Float Valve* 16 - 28 in. lbs. (1.7 - 4.0 Nm) 22-32 in. lbs. (2.4 - 3.5 Nm) Screw, Brake Plate Assembly 60 - 70 in. lbs. (6.7 - 7.8 Nm) NA Screw, Carburetor Mountin

g 20 - 30 in. lbs. (2.2 - 3.4 Nm) 20 - 30 in. lbs. (2.2 - 3.4 Nm) Screw, CD I Screw, Cylinder to Crankcase 55 - 90 in. lbs. (6.2 - 10.0 Nm) 55 - 90 in. lbs. (6.2 - 10.0 Nm) Screws, En Screw, Float Bowl 10 - 13 in. lbs. (1.1 - 1.5 Nm) 10 - 13 in. lbs. (1.1 - 1.5 Nm) Screw, Muffler (611228) 55 - 90 in. lbs. (6.2 - 10.0 Nm) 55 - 90 in. lbs. (6.2 - 10.0 Nm) Screw, Muffler Cover 55 - 90 in. lbs. (6.2 - 10.0 Nm) NA Screw, Muffler Plate 140 - 200 in. lbs. (16 - 22 Nm) NA Screw, Reed 10 - 13 in. lbs. (1.1 - 1.5 Nm) NA Screw, Rod Cap to Rod 65 - 75 in. lbs. (7.3 - 8.4 Nm) 65 - 75 in. lbs. (7.3 - 8.4 Nm) Screw, Shroud 58 - 70 in. lbs. (6.5 - 7.8 Nm) 58 - 70 in. lbs. (6.5 - 7.8 Nm) Screw, Shroud Base 58 - 70 in. lbs. (6.5 - 7.8 Nm) 58 - 70 in. lbs. (6.5 - 7.8 Nm) Spark Plu Rewind Starter to blower housing NA 20-30 in. lbs. (2.2 - 3.4 Nm) Screw, Manifold NA 55 - 70 in. lbs. (6.2 - 7.8 Nm) Screw, Muffler NA 100 - 130 in. lbs.

gnition Pack 90 - 110 in. lbs. (10 - 12 Nm) 90 - 110 in. lbs. (10 - 12 Nm)

gine Mounting 170 - 220 in. lbs. (19 - 25 Nm) 170 - 220 in. lbs. (19 - 25 Nm)

g 150 - 200 in. lbs. (17 - 23 Nm) 150 - 200 in. lbs. (17 - 23 Nm)

* Overtorquin

g will crack the carb body and cause the engine to run rich page rev 8/06

Page 11

SPECIFICATIONS

Item DuraForce R tek

Nut, Shroud 100 - 130 in. lbs. (10 - 14 Nm) 140 - 170 in. lbs. (16 - 19 Nm) Screw, Starter Bracket to Recoil NA 30 - 35 in. lbs. (3.4 - 3.8 Nm) Screw, Gov Pivot Block to Cyl. NA 30 - 35 in. lbs. (3.4 - 3.8 Nm) Screw, Elect Start to Crankcase 140 - 200 in. lbs. (16 - 22 Nm) 75 - 100 in. lbs. (8.2 - 11 Nm)

Standard Torques

Size US (Metric)

#10 - 24 20 - 30 in. lbs. (5.1 - 6.21 Nm) 1/4 - 20 55 - 90 in. lbs. (6.2 - 10.0 Nm) 5/16 - 18 140 - 200 in. lbs. (16 - 22 Nm)

Carburetor Specifications

Item DuraForce R tek

Type Lawn-Boy, float type, dual-circuit, with primer and choke Body Material Minlon Seat material Brass with Viton tipped needle. Both are replaceable. Inlet Needle “Pop-Off” Pressure 5 psi (.7 k Main Jet 77.5 73.8 Main Nozzle Brass Pilot Jet 37.5 42.5

h Altitude NA

Hi Float Adjustment Float hei

ht .500 ± .030" bowl flange (no gasket) to top of float

/cm2) (Wet)

Page 12

SPECIAL TOOL REQUIREMENTS

Listing

Description Order From Part Number Comments/Use

SPECIAL TOOLS

Air Gap Gau

Piston Ring CompressorOTCTOR 4089Compresses piston rings to allow installation

Wrist Pin Knockout Tool Toro 602884 Used to drive wrist pin out of piston

OTC Tool & Equipment Division SPX Corporation Industrial Park 2013 4th Street NW Owatonna, MN 55060 Telephone: 800-533-0492 Fax: 507-455-7011

e Toro 604659 Sets .010” (.25 mm) gap between flywheel

and coil

into the cylinder

Page 13

TROUBLESHOOTING

Engine Will Not Start When “Cold”

Possible Causes Remedies

Fuel tank is empty Fill with clean, fresh, properly-mixed, unleaded fuel Bad fuel Drain tank and float bowl. Fill the tank with clean, fresh,

unleaded, properly-mixed fuel. Fuel filter plu Air cleaner plu Fouled spark plu No spark at spark plu Insufficient momentum Check for loose blade, mower only Incorrect i Low compression See “En

ine flooded with fuel See “Engine Flooded With Fuel” table

En Reed valves not closed Replace reed valves (DuraForce only) Reed valves stuck closed Free up and run en Primer or choke not operatin

ed Replace fuel tank

ed Wash and re-oil air cleaner element (DuraForce only)

Remove and replace the spark plu

See “Engine Will Not Produce Spark” table

nition timin

Check for sheared flywheel key

ine Has Low Compression” table

ine to clean (DuraForce only)

Fix or replace

Engine Will Start When “Cold”, But Not When “Hot”

Possible Causes Remedies

ine is flooded See “Engine Flooded With Fuel” table

Excessive alcohol in fuel Use no more than 10% ethanol blend. Avoid methanol

ine is overheated See “Engine Overheats” table

ed bowl vent Clean bowl vent

Clo Fuel percolation (vapor lock) Use current season

as for fuel mixture

Page 14

Engine Will Not Produce Spark

Possible Causes Remedies

TROUBLESHOOTING

Spark plu Spark plu Spark plug wire damaged Replace CD pack Coil kill wire

nition coil failed Replace CD pack

I Flywheel ma

wire disconnected Reconnect spark plug wire fouled or damaged Replace spark plu

rounded Locate and eliminate the unwanted ground

nets weak Replace flywheel

Engine Flooded With Fuel

Possible Causes Remedies

Overuse of choke position Take throttle off choke Throttle cable misadjusted Adjust throttle cable, if present Air cleaner plu Fouled spark plu Carburetor inlet needle stuck open or leakin

ed Wash and re-oil air cleaner element (DuraForce only)

Replace spark plu Clean carburetor, replace failed parts, and pressure test

Carburetor Air Vent Clean Air Vent

Engine Has Low Compression

Possible Causes Remedies

Worn piston rin Piston rin Cylinder worn Remove and replace short block

s Replace piston rings or short block

(s) stuck in groove Replace piston and rings

Page 15

TROUBLESHOOTING

Engine Lacks Power

Possible Causes Remedies

Dull blade Sharpen or replace blade, mower only Housin Plu Muffler plu Flywheel key sheared Replace flywheel key Carburetor dirty Clean carburetor Intake air leak Repair or replace failed components(s) Low compression See “En

choked with grass and debris Clean housing thoroughly, mower only

ed exhaust system Clean exhaust ports

ed Clean or replace muffler

ine Has Low Compression” table

Engine Surges

Possible Causes Remedies

Fouled idle circuit Clean idle circuit Air leak Check sealin Restricted fuel flow Check filters and fuel line

ine RPM low Adjust to proper specification. Note: A slight surge at no

load is normal.

surfaces, oil seals, gaskets, and port plugs

Governor link misadjusted (R tek) Adjust Air vane stickin

Clean or replace

Engine Backfires

Possible Causes Remedies

Flywheel key sheared Replace key Muffler filled with carbon Clean muffler Exhaust ports plu Air leak to crankcase Replace seals or re-seal crankcase to cylinder Spark plu

partly fouled Clean or replace

ed Clean ports

Page 16

Engine Overheats

Possible Causes Remedies

TROUBLESHOOTING

Cylinder head coolin Restricted carburetor jets Clean carburetor and jet Improper Coolin

as to oil mix ratio Ensure mixture is correct

air intake plugged Remove foreign material and clean

fins clogged Clean fins thoroughly

Engine Vibrates Excessively

Possible Causes Remedies

Blade out of balance Balance blade or replace if dama Bent blade Replace blade Loose en

Bent crankshaft Replace crankshaft Flywheel out of balance (dama

ine mounting screws Tighten engine mounting screws (engine to plate, plate

to mower housin

ed) Replace flywheel

)

Engine Crankshaft Will Not Turn

Possible Causes Remedies

ine brake incorrectly engaged Disengage brake and inspect and repair as necessary,

mower only Blade jammed in housin Piston seized in its cylinder Inspect and repair or replace Starter jammed Repair starter

Inspect and repair or replace, mower only

Engine Produces Mechanical Knocking Sound

Possible Causes Remedies

Loose blade Inspect and ti

only Loose flywheel Inspect and ti

nition is occurrin

Pre-i Loose rod cap Replace rod and bearin

See “Engine Pre-Ignites” table

hten blade nut to correct torque, mower

hten flywheel nut to correct torque

Loose en

ine mounting bolts Tighten bolts

Page 17

TROUBLESHOOTING

Engine Pre-Ignites

Possible Causes Remedies

Wron

spark plug - too hot Install the correct type of spark plu Low quality fuel (old or stale) Replace with fresh, unleaded regular fuel Carbon buildup in en Excessive alcohol in fuel Replace with fresh unleaded fuel havin

Sheared flywheel key Inspect and repair

ine Decarbon engine and muffler

no more than

10% ethanol

Engine Smokes Excessively (Smoke is light colored, engine runs well)

Possible Causes Remedies

Sli

ht oil accumulation in crankcase None; normal on start-up

Air cleaner element clo

Fuel/oil mixture too rich Drain fuel tank and fill with fuel of correct mixture Choke is in “On” position Move to hi

ed Clean and re-oil or replace air cleaner element, mower

only

h speed or “Off” position

Engine Smokes Excessively (Smoke is dark, engine runs poorly)

Possible Causes Remedies

Carburetor runnin Choke is in “On” position Move to hi

too rich Clean and check carburetor

h speed or “Off” position

Page 18

TROUBLESHOOTING

Engine Stalls

Possible Causes Remedies

ine out of fuel Refill with fresh fuel of the correct mixture ine overloaded Unload engine and restart

En Fuel filter plu Spark plu Fuel cap vent plu

nition inadvertently grounded Inspect and repair to remove unwanted ground

I Carburetor vent plu

ine overheated Clear debris from fins or cause of overheatin

En Improper lubrication Tear down and inspect for damage

ed Clean fuel filter/tank

fouled See “Spark Plug Fouled” table

ed Replace fuel cap

ed Clear vent of obstruction

Spark Plug Fouled

Possible Causes Remedies

Incorrect spark plu Carburetor running too rich Clean/rebuild carburetor

ed air cleaner element Clean and re-oil element or replace, mower only

Clo Overuse of “choke” position Move control off “choke” position and check throttle

Use correct spark plu

cable adjustment Weak i Worn rin Use of poor fuel Drain fuel tank and replace with fresh, unleaded re

Fuel/oil mixture too rich Drain fuel tank and fill with fuel of correct mixture Wron

nition system Replace CD ignition pack

s and/or cylinder Rebuild engine or short block

fuel havin

Oil Use Toro 2-cycle oil, Lawn-Boy DuraForce oil, or

NMMA TCW3 approved oil

the correct oil mixture

ular

Page 19

THIS PAGE INTENTIONALLY LEFT BLANK

Page 20

Recommended Maintenance Schedule

Frequency Item Comments

MAINTENANCE

5 Hours Fasteners Check blade and en

frequently. Keep all nuts, bolts, and screws ti

ht to ensure safe operation.

25 Hours Housin

Spark Plu

50 Hours Air Filter (Mower only.) Remove and clean each

Blade

Blade Brake

(Mower only.) Remove the buildup of grass clippin

(Self-propelled mower only.) Clean clippin mechanism cover and drive belt.

Clean, inspect, and regap; replace if necessary.

mowin frequently if operatin

(Mower only.) Sharpen or replace; maintain more frequently if ed rou

Check stoppin of each mowin within 3 seconds of releasin repair or replace.

s and dirt.

s and debris under drive belt

season or every 50 hours; more

h or sandy conditions.

ine mounting fasteners

rass

conditions are dusty.

e is dulled quickly in

time every 50 hours or at start

season. Blade must stop

bail. If not,

Lubrication (Self-propelled mowers only.) Grease rear

Exhaust Ports Clean every 50 hours or at least once each

Fuel System Check for leaka

100 Hours Coolin

hei

ht adjuster brackets.

season.

e and/or deterioration of fuel

hose. Replace if necessary.

System Clean grass clippings, debris, or dirt that clog

ine air cooling fins; clean more frequently

under dirty or hi

h chaff conditions.

Page 21

MAINTENANCE

g g

Air Filter (Mower Only)

Once every season, or every 50 hours, clean the air filter housing and element. Do so more frequently under dusty conditions.

Note: Do not operate the en place. Doin excessive en

1. To remove air filter (A), snap cover latch open, swin and air filter. (See Fi

so may damage the engine or cause

ine wear.

to side, and unhook. Remove the cover (B)

ine without the air filter in

ure 1.)

Note: Be sure filter is properly seated in air box and is not puckered (allowin dirt to carburetor).

direct passage of air and

Figure 3

3297-007

Spark Plug

A spark plug that is dirty, pitted, carbon covered, or has worn electrodes may cause hard startin operation.

Replace spark plu which ever occurs first. Use NGK BPMR 4A or equivalent.

once a season or every 25 hours,

and poor

Figure 1

2. Wash air filter in laundry detergent and water. Squeeze filter to remove excess liquid and blot dry with a paper towel or ra

out the element or damage may occur.

wrin

3. Apply one tablespoon SAE 30 or similar oil to the air filter (see Fi oil is distributed evenly throu li

htly with paper towel to remove excess oil.

Replace filter with cleanest side facin

ure 3). Lightly squeeze filter until

(see Figure 2). Do not

Figure 2

hout the filter. Blot

3297-005

3329-006

carburetor.

1.Set spark plu Fi

ure 4.)

.030 in. (.76mm)

IIIIIIIIIIIIIIIIII

2. Install spark plug finger tight, then torque per specifications. (See Fi

ap to .030 (.76 mm). (See

Figure 4

ure 5.)

3297-008

Figure 5

3297-009

Page 22

Cleaning the Exhaust System (Lawn

Mower)

MAINTENANCE

Warning: Disconnect the spark plug wire to prevent accidentally startin

1. (Mower) Usin remove the blade nut that secures both the mulch fan and blade to the en

loves to hold the blade while removing the nut. (See Fi merely for convenience while workin

ure 6.) Note: Removing the blade is

the engine.

a 1/2" drive with a 15/16" socket,

ine. Use heavy-duty

Figure 8

3. With the cover and exhaust pipe removed, you can see into the passa the en the exhaust requires cleanin and separate the en the exhaust ports. If the muffler requires cleanin it can be removed by removin either side of the muffler passa and one throu Fi carbon loose. Do not use a metal scraper.

ine (A) and passage to the muffler (B). If

ure 9). Use a stick of wood to scrape the

e leading to the exhaust port of

, remove the engine

ine and base for access to

the 2 screws on

e (see Figure 8)

h the side of the muffler (see A in

1657-001

ure 6

(Snowthrower) Remove 2 bolts holding the muffler to the en step 3.

2. Remove the cover and the exhaust pipe under the

ine block. Remove the muffler. Proceed to

cover. (See Fi

ure 7.)

ure 7

0893-011

1657-010

ure 9

4. The muffler (B) can be removed from the top of the mower to inspect for carbon buildup. (See Fi

9.)

16057-009

ure

Page 23

MAINTENANCE

Cleaning the Exhaust System (Snowthrower)

1. Remove the muffler (see Figure 10.) Clean as needed.

Figure 10

2. Inspect exhaust port (see Figure 1 1). If cleaning is necessary , rotate piston to cover exhaust port, and scrape carbon from exhaust port area. Use wood only to clean this area.

0893-012

Reassembling Exhaust System (Mower Only)

1. Install the exhaust pipe into the engine base (see ure 12).

Figure 12

2. The cover on the exhaust portion of the engine

base uses a hi joint. Apply a coat of Loctite 598 or equivalent to the sealin four screws per specifications.

h temperature silicone to seal the

surfaces before assembly. Torque the

16547-006

Figure 11

3. Install the muffler and torque the bolts per specifications.

0893-035

3. Re-install the blade and mulch fan, if removed. Ti

hten the nut per specifications.

Page 24

Identification

The E series engines use two versions of the primer start carburetor. One with an air filter box on the mower en filter box on the snowthrower en Differences include a plu carburetor vent passa the throttle shafts, jettin Both carburetors have two circuits and use both a choke and primer for startin

ines (DuraForce) and one without an air

ines (R tek).

in the snowthrower

e and some minor differences in

and throttle valve bleed hole.

. (See Figure 13.)

CARBURETOR

A. Venturi B. Center Passa

The fuel/oil mix is then picked up by, and mixed with, the movin throttle openin enters the crankcase throu (DuraForce), or ports (R tek). (See Fi Fi

ure 16.) When the piston moves away from the spark plu the now pressurized crankcase causes the mixture to move into the combustion chamber.

air, the amount of fuel determined by

and jet size. This fuel/oil/air mixture

, the cylinder intake ports are opened and

ure 14

C. Air Pressure

e Area

h the reed valves

ure 15 and

3297-012

ure 13

0720-012

Theory of Operation

As the crankshaft rotates, the piston moves back and forth in the cylinder, alternately creatin partial vacuum in the crankcase. (See Fi

As the piston moves toward the spark plu valve opens (see Fi uncovered (see Fi throu

h the carburetor throat to equalize the pressure in the crankcase. The carburetor throat is formed into a venturi (lar passa pressure at the center of the passa

By insertin the venturi (see Fi the venturi causes the normal air pressure in the bowl to push fuel up the tube.

e at each end but with a smaller center

e). When air rushes through the venturi, air

a tube from the carburetor float bowl into

ure 15) or the inlet ports are

ure 16). This causes air to rush

ure 14), the lower air pressure at

a pressure or a

ure 16.)

, the reed

e is lowered.

Reed Valve

A. Reed Valve Closed B. Exhaust Gases

Piston Ported

Figure 15

C. Second Stroke

3297-021-3

Figure 16

A. Intake Ports Closed

nition

B. I

C. Third Port Open D. Partial Vacuum

3297-002

Page 25

CARBURETOR

Troubleshooting

Engine Starts Hard

Possible Causes Remedies

Primer malfunction Repair or replace as necessary No fuel in carburetor Add the proper fuel-oil mix Carburetor bolts looseTi Mislocated Choke not closin

askets Loosen bolts, realign gaskets, and tighten

fully Adjust choke or throttle/choke cable

hten bolts to 20 - 30 in.lbs. (2.2 - 6.2 Nm)

Engine Runs Rich

Possible Causes Remedies

Dirty air cleaner Clean or replace and re-oil air filter element

(DuraForce en Dirt in carburetor Clean carburetor, fuel line and tank Primer line pinched Inspect and correct problem Dirt in primer vent Clean and/or replace as necessary Choke not openin

fully Adjust choke or throttle/choke cable

ines)

Engine Runs Lean

Possible Causes Remedies

Carburetor bolts not ti Crankcase Main jet partially clogged Clean jet Pilot jet or circuit clo

askets or seals leakin

ht Tighten bolts to specifications

Replace or reseal

ed Clean pilot jet and passages

Fuel Leaks From Carburetor (Leaking is continuous and fully drains fuel tank)

Possible Causes Remedies

Dirt under inlet needle Remove inlet needle and seat. Then clean or replace

and pressure check. Bowl vent plu Float sinkin Float stuck (

ed Remove bowl and clean with compressed air

(heavy) Replace float

ummed carburetor) Remove bowl and clean carburetor

Page 26

CARBURETOR

ge g

Fuel Leaks From Carburetor (Leaking starts after running, stops after shutdown)

Note: This condition which does NOT drain the fuel tank is called “spit-back”.

Possible Causes Remedies

ine RPM out of proper range Adjust to proper range (experimentation within the

RPM ran

e may be necessary)

Exhaust partially plu

s leakin

Rin Float hei Reeds not sealin

ht incorrect Re-set float

ed Decarbon exhaust port and muffler

Preliminary Check

The primer start carburetor used in E Engines has an all Minlon housin and an adjustable float. Perform the followin some of the possibilities that may contribute to carburetor malfunction:

1. I

nition system - ensure that all components are

adjusted to specs and are the correct components.

2. Fuel tank filter - must not be plu

3. Fuel cap vent - hole must not be plu

4. Air filter - must be clean and oiled (DuraForce ines).

5. Crankcase seal - Crankcase seals must be

installed properly and in value on the bolts must be correct.

with a fixed high speed and pilot jet

preliminary checks to eliminate

ed.

ood condition; torque

Break in new engine or repair worn rings/cylinder

Repair/replace reeds (DuraForce only)

Removal of DuraForce Carburetor

1. Disconnect spark plug wire. We strongly recommend cleanin before removal from the machine. This reduces the chance that dirt can will extend the life of the solvent in your cleanin tank.

2. Remove fuel line and drain; remove the fuel tank. On snowthrowers, it will be necessary to remove the lower shroud to access the carburetor and fuel line.

3. Open and remove air cleaner cover and air filter element (mower only). (See Fi

4. Detach carburetor from en mountin carburetor shield. Keep the heat shield for later installation. (See Fi

screws. Discard the two smaller

askets on either side of the carburetor

ure 17.)

the exterior of the carburetor

et into the carburetor and

ure 17.)

ine by removing two

6. Carburetor flan be installed correctly.

7. Exhaust ports - must not be restricted.

8. Fuel - mixture must be fresh. As becomes more difficult to i

9. Governor air vane - must move freely.

askets and heat shield - must

asoline ages, it

nite.

Heat Shield

Mounting Screws

ure 17

0893-045

Page 27

CARBURETOR

5. Disconnect the primer tube from the carburetor fittin

. (See Figure 19.)

6. Pull the carburetor assembly down and away from the en the hole in the shroud mountin

7. Remove the throttle cable screw and nut from the throttle cable mountin

CAUTION: Be careful in the next step to avoid dama

8. Slide the plastic control lever to either end of its adjustment and snap it to the locked position to help restrict its movement while you disconnect the throttle cable from the control lever.

ine such that the air vane governor clears

base.

bracket.

e to the delicate governor spring.

Removal of R tek Carburetor

1. Disconnect spark plug wire. We strongly recommend cleanin before removal from the machine. This reduces the chance that dirt can will extend the life of the solvent in your cleanin tank.

the exterior of the carburetor

et into the carburetor and

4. Disconnect the primer tube from the carburetor fittin

(see Figure 19).

5. Disconnect the adjustment arm, and remove the choke cable. (See Fi

6. Pull the carburetor assembly down and away from the en the hole in the shroud mountin

ure 19.)

ine such that the air vane governor clears

overnor spring from the

Figure 19

base.

0893-039

2. Remove fuel line and drain; remove the fuel tank. On snowthrowers, it will be necessary to remove the lower shroud to access the carburetor and fuel line.

3. The carburetor is attached to the intake pipe by two screws, which are screwed into two captured nuts. The nuts are held in their pockets by a rubber band durin

the manufacturing process. If the rubber band is no lon purpose fallin

out of the pockets. Remove the two screws

and discard the

er in place, smear some general

rease on the nuts to prevent them from

asket. (See Figure 18.)

Disassembly

1. NOTE: The exterior of the carburetor should be cleaned before removal from the machine. If this has not been done, clean the outside before disassembly. At the throat of the carburetor, usin needle nose pliers, of the throttle shaft. (See Fi orientation of the small protrusions on the throttle plate as you pull it out.

ently pull the throttle plate out

ure 20.) Notice the

Figure 20

Figure 18

0893-009

0893-007

Page 28

CARBURETOR

2. Hold the governor collar on the carburetor and lift the air vane/throttle shaft out of the carburetor. For DuraForce en up, detachin lever. (See Fi

3. Turn the carburetor over. Remove the four bowl retainin (See Fi

ines only - Lift the collar and spring

the spring from the speed control

ure 21.)

ure 21

screws, the bowl gasket, and the bowl.

ure 22.) Discard the bowl gasket.

0893-005

4. The pilot jet is located under the decal on the side of the carburetor. Remove the decal and the pilot jet. Note: The threads have Loctite on them. (See Fi

ure 23.)

ure 23

5. Remove the fuel filter from the fuel nozzle (see Fi

ure 24).

0893-30

ure 24

ure 22

0893-002

0893-22

Page 29

CARBURETOR

6. Remove the float hin assembly (with its clip), and the float (see Fi

25). Discard the needle and clip.

7. Inspect the float for cracks or deterioration of the cork (see Fi

ure 26).

e pin, the inlet valve needle

Figure 25

ure

0893-18

9. Remove the high speed jet (A) from the nozzle (B). It is best to clean the nozzle in place. If the nozzle is not sealed into the carburetor body, the air/fuel mixture will be affected (see Fi

Note: There are two white nylon plu carburetor. Do not attempt to remove them or the carburetor will be dama

ed.

Figure 28

ure 28).

s in each

0893-037

Figure 26

8. Remove the brass inlet fuel valve seat and discard it. (See Fi

ure 27.)

0893-001

Cleaning and Inspection

1. With the carburetor completely disassembled, thorou solution. Do not soak the carburetor. Leave it in the solvent only lon for wear or deterioration. Use a spray can of carburetor cleaner with the hose, and flush all passa passa

CAUTION: If ta restrict any passa

2. Always check the carburetor mountin the fuel bowl mountin smooth and undama

hly clean all parts in a parts cleaning

enough to clean it. Inspect

es with cleaner. Blow dry all carburetor es with compressed air.

wire is used, never enlarge or

eway in the carburetor.

flange and

flange to be sure they are

ed.

Figure 27

0893-041

Page 30

CARBURETOR

Assembly

1. Install the high speed jet into the fuel nozzle.

2. If the nozzle has been removed, turn the carburetor over. Apply one drop of Loctite 242 blue or equivalent to the nozzle threads, and install the nozzle assembly into the carburetor body (see Fi

ure 29).

ure 29

3. Apply one drop of Loctite 242 blue to the threads, and install the pilot jet (see Fi

ure 30).

0893-038

4. Apply one drop of Loctite 242 or equivalent to the seat threads, and install a new brass inlet fuel valve seat (see Fi

5. Install a new inlet valve needle and clip on the float.

6. Install the float assembly with a new float hin in the bottom of the carburetor. Ensure that the hin

e pin is positioned properly to keep the float level. The float should be free to move up and down easily in the carburetor body.

7. Adjust float so hei bowl flan

ure 32).

e (gasket not in place) to top of float (see

ure 31).

ure 31

ht is 1/2 ± .03” (.76 mm) from

0893-041

e pin

ure 30

0893-030

ure 32

0893-054

Page 31

CARBURETOR

gaug

8. Pressure check carburetor. Attach pump with pressure (see Fi

e to fuel inlet fitting on carburetor

ure 33). With carburetor upside down (float up), raise float and lower to its normal position. Pump pressure to 5 psi. It should hold this pressure indefinitely. For practical purposes, test for 10 or 15 seconds. If it does not hold, wet the needle and seat, and repeat the test.

Figure 33

0893-026

10. Install a new fuel bowl gasket and the fuel bowl with the four bowl retainin

Figure 35

screws (see Figure 35).

0893-002

11. Hook the governor spring into the bottom of the

overnor collar (DuraForce engines). See Figure

36.

9. Install the fuel filter over the fuel nozzle. Pressure check before proceedin

(see Figure 34).

Figure 34

0893-22

Figure 36

0893-050

12. Place the collar and spring over the carburetor fittin

(DuraForce engines). See Figure 37.

Figure 37

0893-005

Page 32

13. Install the air vane and throttle shaft into the

carburetor body by very carefully pushin

h the collar into the carburetor body. (See

throu Fi

ure 37.)

14. Push the throttle plate into the throttle shaft. (The plate only inserts one way.) If the throttle plate does not fit snu

overnor spring can now be attached to the throttle

shaft. Note: Be sure air vane operates smoothly and

does not stick or bind.

ly, replace the throttle shaft. The

the shaft

Installation

1. DuraForce - Assemble the carburetor, gaskets, heat shield, and air filter box. Use the two mountin assembly.

R tek - Assemble the carburetor, spit cup, heat shield, and hold parts to

screws to hold the parts together during

askets. Use the mounting screws to

ether during assembly.

CARBURETOR

ure 38

4. Install the fuel line and primer tube on the appropriate carburetor fittin

5. Check that the choke and air vane assembly move freely and is properly adjusted. If the air vane requires adjustin pa

e 26.

, see Presetting the Governor on

724-004

2. DuraForce en the openin the base, and attach the carburetor to the en with two mountin specifications.

3. DuraForce en throttle cable into the vertical tab of the speed control lever. Set the throttle to fast and the speed control lever so that the throttle plate is in the full open position. The cable is adjusted at the cable clamp on top of the air filter box.

R tek en throttle plate and the tab on the block. Connect the

overnor rod adjusting loop (A) up to the air vane, and connect the choke cable. Assure the throttle is in the full open position. (See Fi

40.)

ines - Guide the air vane through

in the shroud base from the bottom of

screws. Tighten them to

ines - Insert the bent wire of the

ines - Connect the governor spring to the

ure 38 and Figure

ine

6. Install the air filter element and cover (DuraForce en

ines only). The R tek engine has a spit cup (B) only. Note: The openin pointed up. (See Fi

of the spit cup should be

ure 38.)

Governor Theory

Reed Valve Engine (DuraForce Engines Only)

The shaft of the governor air vane is attached to the throttle disc of the carburetor so that air flow, created by the rotatin The

overnor spring resists this force and attempts to open the throttle. The balance between these two forces is the may be chan produces a 50 - 75 RPM chan each adjustment “click” it is moved. (See Fi

flywheel, attempts to close the throttle.

overned engine speed. Spring tension ed via an adjustable collar which

e in engine speed for

ure 39.)

Page 33

CARBURETOR

Figure 39

0720-07

Piston Ported Engine (R tek Engines Only)

The piston ported engine does not use the “click" type adjustment. For the piston ported en

overnor is adjusted by bending the bracket that the overnor spring is attached to. Otherwise, the function

of the

overnor is the same (see Figure 40).

ines, the

2. Use a tachometer to check en 300 RPM for DuraForce en

For R tek (piston ported) en specification pa

Should the adjustment will be necessary. (See Fi

A good starting point is about 1¼” (31.75 mm) from the castin Then move the air vane until the throttle is full open. The air vane must not contact the CD i the

overnor spring be removed, reinstall with both the

open ends of the sprin

overnor link (A) be bent or replaced,

to the end of the air vane. (See Figure 42.)

es.

Figure 41

facing you.

ine speed; 2900 ±

ines on mowers.

ines refer to the

ure 41.)

0893-039

nition. Should

Figure 40

Presetting the Governor

3S-001

(31.75 mm)

(DuraForce Engines Only)

Note: Each “click” of the governor collar represents approximately 50-75 RPMs.

1. Turn the collar clockwise to increase sprin (and en decrease sprin

39.) Preset the clockwise.

ine RPMs) or counterclockwise to

tension and RPMs. (See Figure

overnor collar 3 or 4 clicks

tension

Figure 42

7.tif

Page 34

Servicing the Air Filter

(DuraForce Engines Only)

1. To remove the air filter, unsnap the wire holder on ht side of the cover the cover. Rotate the

the ri cover open. The air filter element can now be removed. If you wish to remove the cover, rotate it full open and unhook it from the hin

43.)

e. (See Figure

CARBURETOR

ure 43

2. Clean and re-oil the air filter element according to

the procedure in Maintenance section. CAUTION: Do not operate the en

filter element or with a dry element; en be shortened.

Note: Snowthrower en filter for two reasons:

a. The snow prevents dirt from b. In colder weather, the snow will blow around.

Fine particles of snow would clo The en amount will not cause a problem.

ine will ingest snow, but that small

ines do not have an air

ine without a

etting into the air.

0893-017

ine life will

the air filter.

Page 35

THIS PAGE INTENTIONALLY LEFT BLANK

Page 36

FUEL SYSTEM

Operation

The E engine uses a plastic fuel tank with a nonreplaceable 75 micron in-tank filter screen. The filter is welded in the bottom of the tank over a sediment reservoir. The tank is mounted above the level of the carburetor and uses .25" I.D. (6.35 mm) rubber hose to the carburetor. The fuel hose is friction-fitted to the tank outlet at one end and to the carburetor at the other end.

The fuel tank is vented throu cap. The fuel openin outlet, helpin funnels and into the fuel tank durin the cap also prevents interference with the startin rope in Zone Start mower applications.

The fuel cap is a four piece desi an inner sealin in the body of the cap. The baffle assembly allows expansion in the tank or splash a the cap, without the loss of fuel. Atmospheric pressure is allowed into the tank from an openin allow individual part of the cap fails, the entire assembly must be replaced.)

ravity to feed fuel to the carburetor. (If an

to prevent damage to the filter screen by

asoline filler spouts that may be inserted

ravity to supply fuel through a

h an opening in the fuel

on the tank is opposite the fuel

refueling. The placement of

n (see Figure 44) with

disc that is vented to a baffle assembly

ainst the bottom of

in the cap to

Fuel Cap Service

1. The fuel cap may not be disassembled; however, the vent openin should be kept free of debris.

2. The ventin fillin

the cap with water and observing the flow of water out of the vent openin If water does not drain, the vent openin plu

ed or restricted.

3. If the fuel cap will not vent properly, replace the entire cap assembly.

4. Should you encounter a situation where fuel leaks around the threads of the fuel cap (not out the vent), inspect the top of the neck of the fuel tank and the area in the cap where the fuel tank neck contacts the cap. This is the sealin threads. (See Fi

on the cap and inner sealing disc

ability of the cap may be tested by

in the top of the cap.

may be

area, not the

ure 45.)

ure 45

720-021

Cleaning

1. Remove the fuel tank. Take it to an appropriate area, and wash the tank in clean solvent intended

ure 44

0720-022

for cleanin

2. Backwash the filter screen by directin solvent, under moderate pressure, throu sediment reservoir and screen, opposite the direction of fuel flow.

3. Wash the tank a

4. Clean or replace the fuel hose.

engine parts.

ain with clean solvent.

cleaning

h the

Page 37

THIS PAGE INTENTIONALLY LEFT BLANK

Page 38

IGNITION SYSTEM

Troubleshooting

Problem Possible Cause Suggested Remedy

Misfirin en symptoms may also be caused by fuel system problems)

, no firing, engine surges,

ine dies (Note: these

ine will not stop Broken ground wire Check the ground wire between the

Spark plu Spark plug in poor condition Replace plu CD Pack air gap wron CD Pack hi CD Pack leads loose, dirty, or

roundin CD Pack defective Replace CD Pack Flywheel key dama

Flywheel ma or weak

or lead wire loose Tighten plu

Adjust

h tension lead loose Secure with GE silicon sealant

Clean and tighten leads/replace

ed or sheared Replace key and check keyway

nets demagnetized

(see Servicin section)

Replace flywheel

and kill switch. Look for

breaks or loose connections.

the Flywheel in this

Testing

Check the ignition system in the following order:

1. Spark plu

2. CD Pack (air

3. Flywheel (key and ma Use the table above to aid in dia

(connection & wire, condition).

ap, connections or spark).

nets).

nosing the problem.

Spark Plug Operation

The spark plug ignites the oil-fuel mixture by producing a spark just before the piston reaches top dead center (TDC). A spark plu (See Fi

ure 46.)

is typically constructed as shown.

A. Metal Shell B. Center Electrode C. Ground Electrode

ure 46

D. Head Insulator E. Copper core F. Le G. Gap

3297-014

Insulator

Page 39

IGNITION SYSTEM

Spark Plug Service

1. Check spark plug with the chart in this subsection and replace followin this pa

the specifications given on

CAUTION: Do not clean plu

2. Clean with a wire brush removin buildup. Check conditions of the plu or dama

Item Specification/Action

Plu

type NGK BPMR4A or

Frequency of chan Check, clean, and Gap See specifications Torque value See specifications

e. Replace as necessary.

e As needed ap Every 50 hours

with a sand blaster.

the carbon

for cracking

equivalent

CD Pack Operation

The Capacitive Discharge (CD) system (see Figure 47) is breakerless and contains electronic components that replace mechanical points and related accessories (such as a breaker cam, spark advance assembly, etc.).

Figure 48

When the SCR is triggered or “fires”, up to 200 volts DC, stored in the capacitor, travels to the spark coil. Here it is stepped up to as much as 25,000 volts and is dischar (See Fi

nition timing (when the SCR fires) is also determined by the flywheel key and the keyways in the flywheel and crankshaft. Dama affect the i

ed across the electrodes of the spark plug. ure 49.)

e to any of these parts will

nition timing.

3297-016

Figure 49

Figure 47

A. CD I

As the flywheel magnet passes the CD Pack, an AC volta is converted by a rectifier into a DC si then stored in a capacitor. (See Fi

nition Module

e is induced into the charge coil. This AC voltage

nal, which is

ure 48.)

3297-015

3297-017

Page 40

IGNITION SYSTEM

gaug

ging

At slower speeds, the flywheel magnet induces a smaller char the silicon controlled rectifier (SCR) enablin startin before top dead center (BTDC). (See Fi

A. Pole Shoe B. Flywheel Rotation C. Crankshaft at 5° BTDC

At faster speeds (about 800 RPM), the flywheel

nets induce a large enough charge in the trigger

ma coil to tri (about 28 de

e in the trigger coil. This action triggers

easier

in a “retarded firing position” about 5 degrees

ure 50.)

ure 50

D. Magnet E. Startin F. Charging Le G. Pole Shoe

er the SCR in the “advanced firing position”

rees BTDC). (See Figure 51.)

3297-018

CD Pack Air Gap Adjustment

1. Rotate the flywheel until the magnets are directly adjacent to the CD Pack as shown. (See Fi

52.)

.010”

(.25 mm)

ure 52

2. Adjust gap by loosening screws, inserting LawnBoy mm) shim stock and ti the shim stock or

e (P/N 604659) or a piece of .010" (.25

htening screws. Remove

ure

lbv0040a

CD Pack Removal/Installation

1. Disconnect leads and remove mounting screws.

A. Flywheel Rotation B. Crankshaft at 25°

BTDC

ure 51

C. Char D. Running Leg 25°

Advance

3297-019

2. Replace CD Pack, and set 1 above. Ti torque values. (See Fi

hten screws. See specifications for

ure 53.)

ure 53

ap as outlined in step

lbv0040b

Page 41

IGNITION SYSTEM

Flywheel Operation

The flywheel is connected directly to the crankshaft (secured by a flywheel key and nut) and turns at the same speed as the crankshaft. Two permanent

nets, imbedded in the flywheel, rotate past the coil

ma in the CD Pack to be

Imbedded in the opposite side of the flywheel are steel counterwei These counterwei

A flywheel key and keyway in the flywheel and crankshaft are used to assure ali assembly. The tapered fit of the flywheel and crankshaft alon actually holds the parts to tapers must be key is desi stops rapidly , due to blade impact, the key will shear. If the key were too hard and the impact occurred, the more expensive flywheel could crack.

hts which offset the weight of the magnets.

ned as a light duty part so that if the engine

in the generation of electricity.

hts are not magnetic.

nment during

with the torque of the bolt or nut

ether. The surfaces of both

ood to obtain a good friction fit. The

Flywheel Removal

3. Remove the flywheel by pulling up on the edge of flywheel while strikin hammer. (See Fi

4. Remove key and check its condition (see Figure

56).

the flywheel nut with a soft

ure 55.)

ure 55

lbv0040b

1. Remove shroud and fuel hoses.

2. Remove flywheel nut and starter cup. Reinstall nut flush with the end of the crankshaft. (See Fi

54.)

Figure 54

ure

0893-21

Figure 56

5. Replace crankshaft and/or flywheel if keyway is distorted or cracked.

0893-006

Page 42

IGNITION SYSTEM

6. Inspect the flywheel for cracks or damage and the stren

th of the magnets using a iron object.

Replace as necessary. (See Fi

ure 57

ure 57.)

0893-013

Flywheel Installation

1. Make sure flywheel taper, crankshaft taper, and keyway is absolutely clean and dry.

4. Torque flywheel nut to specifications (see Figure

59.)

ure 59

0893-025

2. Make sure key is installed correctly (see Fi

58.)

3. Locate keyway cutout in flywheel over key and shaft.

ure 58

ure

3297-020

Page 43

THIS PAGE INTENTIONALLY LEFT BLANK

Page 44

REWIND STARTER

gag

Operation

The rewind starter operates through a retainer/friction disc that causes two en the center of the rewind starter and en of the starter hub on the flywheel. The en do

s move into contact with the starter hub when the rewind rope is pulled. When the en starter cup accelerates. As the speed of the starter cup exceeds the speed of the recoil starter, the ramps on the inside of the starter cup will contact the back side of the starter do starter rope is relaxed, the sprin retract.

s and push them inward. Also, if the

ement dogs to extend from

e the inside

ement

ine starts, the

will cause the dogs to

Removal and Disassembly

Note: The rewind starter assembly housing is attached to the shroud with rivets.

1. Remove any necessary shroudin

tank. Remove the fuel tank.

2. Remove the two hex head screws (A) that attach

the shroud to the base. Also, there are 2 studs (B) on the cylinder head that are used to attach the shroud. Remove the nuts and washers from the studs. The shroud can then be rotated towards the cylinder head until there is enou slide the shroud off the studs. (See Fi

to reveal fuel

h clearance to

ure 60.)

4. This recoil starter is a pressed to Due to the low cost of the assembly, we do not stock individual parts. Should the recoil fail due to somethin recommend replacin replacement recoil will be connected to the shroud with nuts and bolts.

other than a starter rope, we

the assembly. The

ether assembly.

Reassembly

Both the DuraForce and R tek engines use starter ropes about 7 feet lon

1. To wind the rope and pretension the sprin the pulley counterclockwise — six (6) turns for the R tek and 5 turns for the DuraForce. Insert the rope throu small needle nose pliers will be helpful. (See Fi

ure 61.)

h the guide, then the reel. A pair of

, turn

ure 60

3. Drill out the rivets connecting the recoil and the shroud. Note the orientation of the starter.

720-002

ure 61

0893-010

Page 45

REWIND STARTER

2. Tie a sin the end with a li the rope from frayin knot in the rope to prevent too much from retractin until the starter handle is installed.

3. Reassemble the starter and shroud with the four screws and nuts. Remember the orientation of the rope outlet.

le knot in the end of the rope; then singe

hter to prevent the knotted end of

(see Figure 62). Tie a simple

Figure 62

lbv0043d.bmp

4. The shroud must be assembled by slippin shroud over the two studs on the cylinder head then rotatin

ine block and shroud align. Install the nuts on

en the studs and two screws on the side opposite the head. Note: Do not overti

the shroud down until the holes on the

hten. (See Figure 63.)

Figure 63

the

0720-002

Page 46

General Information

In this section, we will cover both versions of the E series en and the R tek is piston ported. The desi affects the path which the incomin takes to

ine. The DuraForce is a reed valve engine,

n difference

fuel/air charge

et to the firing chamber.

ENGINE

Two-cycle en make their use more practical in certain applications. Two-cycle en power-to-wei position, limited only by the carburetor and fuel supply system. They are also notably easy to maintain and service because of their uncomplicated desi

ines have special advantages which ines are lightweight with an excellent

ht ratio and can be operated in any

Theory of Operation

Reed Valve Engine

The illustration below (see Figure 64) shows what happens inside the en revolution. Fuel intake, fuel i burned rotation of the crankshaft.

ases all take place during a single 360-degree

ine during one full crankshaft

nition, and the exhaust of

ure 65

A. Reed Valve Open

The crankshaft continues its rotation, and the piston be

ins its travel toward the spark plug. As it moves, the piston seals off the transfer port first, then the exhaust port. When both ports are sealed, the remainin prepare it for i spark plu Fi

ure 65.)

The movement of the piston towards the spark plu also has an important effect in the crankcase. Once the transfer port is sealed, a vacuum is created in the crankcase. This action pulls the reed valve open and draws in a fresh char

Just before the piston reaches top dead center (TDC), the spark plu properly, the fuel/air mixture i that occurs evenly throu piston chan the crankcase.

travel compresses the air/fuel mixture to

nition. The travel of piston towards the

is called the compression stroke. (See

e of fuel/air mixture.

fires. When the engine is functioning

nites, causing a burn

h the power stroke. The

es direction and begins its travel towards

3297-021-2

NOTE: If the compression ratio is too hi

ure 64

A. Reed Valve Closed B. Exhaust Gases

Beginning at a point where the top of the piston is just below the exhaust port, the piston moves forward toward the crankcase. As the transfer port is uncovered, the fuel/air mixture stored in the pressurized crankcase is forced into the combustion chamber. (See Fi

ure 65.)

3297-022-2

mixture actually explodes before it is i spark plu detonation (also called “knock”).

When the piston opens the exhaust port, hi exhaust movement of the piston towards the crankcase uncovers the transfer port which allows a fresh char of air/fuel mixture to enter the combustion chamber. As the exhaust the en

. This can be heard and is identified as

ases exit the exhaust port. Further

ases continue to exit the exhaust port,

ine is readied for another cycle.

h, the fuel/air

nited by the

h-pressure

Page 47

ENGINE

Piston Ported Engine

In a piston ported engine, there are no reed valves. The fuel/air mixture enters the crankcase throu third port that is opened and closed by the piston. (See

ure 66.) All other functions are the same as a reed

Fi valve en

A. Intake Ports Closed B. Compression

ine.

Figure 66

C. Third Port Closed D. Partial Vacuum

h a

3297-001-2

When the piston opens the exhaust port, high-pressure exhaust Further movement of the piston towards the crankcase uncovers the transfer port, which allows a fresh char of oil/fuel mixture to enter the combustion chamber. As the exhaust en

A. Intake Ports Closed B. Exhaust Port Openin

ases exit the exhaust port. (See Figure 68.)

ases continue to exit the exhaust port, the

ine is readied for another cycle. (See Figure 69.)

Figure 68

C. Third Port Open D. Pressure Buildin

3297-003

Both Piston Ported and Reed Valve Engines

At about 28 degrees before top dead center (BTDC), the spark plu properly, the air/fuel mixture i that occurs evenly throu compression ratio is too hi actually explodes, which can be heard and is identified as detonation.) The burn continues as the piston chan

es direction and begins its travel towards the

crankcase. (See Fi

fires. When the engine is functioning

nites, causing a burn

h the power stroke. (If the

h, the air/fuel mixture

ure 67.)

Figure 69

A. Intake Ports Open B. Exhaust Port Open

The 2-cycle engine is always well lubricated as long as the correct oil/fuel mixture is maintained in the fuel tank. Oil suspended in the fuel vapor adheres to all movin re

parts, keeping them continually coated,

ardless of operating angle.

C. Fresh Fuel Chan D. Third Port Closed

3297-004

Figure 67

A. Intake Ports Closed B. I

nition

C. Third Port Open D. Partial Vacuum

3297-002

Page 48

ENGINE

gging

Service Tips

1. Cylinder/Crankcase Halves The two halves are a matched pair and cannot be

exchan and assembly procedures in this subsection. Be sure to use Loctite 515 on the matin Torque the six screws that secure the two halves. See specifications.

2. Oil Seal Visually inspect for leaky or dama

locations). See the Seal Service section for the procedure.

3. En This item should be checked and/or cleaned every

100 hours (maximum) to keep carbon from clo enterin Cleanin

ed between engines. Follow all cleaning

surfaces.

ed oil seals (two

ine Base/Muffler Baffle (Lawn mower only)

exhaust system (power loss) and from

engine (causing piston scoring). See

Exhaust, see page 15.

2. Remove the entire crankshaft assembly, and discard the oil seals.

ure 70

3. Carefully remove the HSH (hex, socket head) cap screws (A) (see Fi connectin needle roller bearin liner. (See Fi

rod cap and the split bearing liner. The

ure 71) to remove the

s are under the split bearing

ure 72.)

1657-012

4. Exhaust Ports The exhaust ports should be inspected and

cleaned as necessary (see pa

5. Carburetor Gaskets Carburetor

shield may be leakin leaks into the en fluctuations). Ensure that air cleaner/carburetor mountin Specifications).

askets on either side of the carburetor

or damaged causing air

ine (may cause power

screws are properly tightened (see

e 15.)

Disassembly

Removal of the shroud, recoil starter, flywheel, ignition coil, and carburetor are covered in other parts of this book and will not be repeated here.

1. Remove the six crankcase cap screws, and separate the halves usin Fi

ure 70.) Be careful not to damage the sealing

surfaces.

a screwdriver. (See

ure 71

0720-013

Page 49

ENGINE

g g

4. Remove the piston and rod assembly. Separate the assembly if necessary, usin on the retainin tool (P/N 602884) to punch out wrist pin (17). (See Fi

ure 72.)

5. Remove the two bolts and two nuts retaining the cylinder head to the block. Remove the head and discard the head

ring (16). Use wrist pin knock out

Figure 72

asket. (See Figure 73.)

a snap ring pliers

0893-24b

3. Check all parts for wear or dama questionable.

4. Clean crankcase surfaces with Gel Seal and Gasket Remover. (See Fi

Figure 74

5. Use a feeler gauge to check that the ring end gap is to specifications.

ure 74.)

e and replace if

0720-014h

Figure 75

Figure 73

Inspection and Repair

1. Check bearings for wear and freedom of movement; replace the bearin

2. Check rin for wear or dama Clean any carbon buildup from the rin before installin of hardwood to scrape carbon loose. Should you use a metal tool, you mi

s for sticking. Remove and check rings

e; replace rings if questionable.

new rings. It is best to use a piece

s if questionable.

ht damage the piston.

720-008

rooves

6. Inspect the piston and cylinder (see Figure 75). A ood piston will show most of the machining marks

on the surface. Some thin and cylinder dama

e are:

s that indicate piston

0893-014

Page 50

A. Vertical scratches that appear all the way

around the piston sometimes is combined with discoloration (see Fi way around the piston indicate hi dirt in areas, look more closely to see if they are in line with the ports. On a NEW en ports are not properly deburred, piston dama can result. This can appear ONLY on en with very few hours on them. The dama immediate. If the en couple of hours use, inspect the carburetor, reed area, and crankcase for any si Much of the dirt that an en dama found in these areas indicate that the en has in has in block replacement as the bearin exposed to that dirt also.

estion. If the scratches are in limited

e and goes out the exhaust. Any dirt

ested a great deal more. If an engine ested dirt, the best solution is a short

ure 76). Scratches all the

h hours or

ine, if the

ine has more than a

n of dirt.

ine ingests does its

s have been

ines

e is

ine

C. Cylinder dama

dama made of harder material, it can stand more abrasion. However, it is replace the short block if severe piston dama is present, as it is the most cost-effective repair .

e to the piston. As the cylinder liner is

e is usually less than the

enerally best to

Reed Valve Service (DuraForce Engines Only)

The reed assemblies (see Figure 77) permit fuel mixtures to enter the crankcase on compression strokes and to trap fuel mixtures in the crankcase on power strokes.

ENGINE

ure 76

B. Discoloration of a piston is often caused by

improper lubrication. Without the necessary lubrication, friction increases and overheats the piston. Often in an en improper lubrication, the piston is discolored, the rin crankshaft bearin the piston is the source of the friction and heat, the bearin not appear dama recommend re-usin failed due to improper lubrication.

s may be stuck, yet the lower rod and

s, further from the heat source, may

ine that failed due to

s might appear usable. As

ed. However, we would not

bearings in an engine that

0893-027

ure 77

1. Check clearance between tip of reed and plate; replace reeds if clearance is more than .020" (.5 mm).

CAUTION: Do not use compressed air to clean reeds.

2. Clean reeds carefully, by hand, usin solvent.

0720-018

carburetor

Page 51

ENGINE

3. When replacin centered over openin

78), and use Loctite 271 on threads of screws. Torque per specifications.

reeds, install smooth edge down

s in crankcase (see Figure

Figure 78

0720-020

Reassembly

Assemble the piston and connecting rod. Note the piston has the letters EX and an arrow stamped into the top. The arrow should point towards the exhaust port. The connectin piston two ways. As the rod is symmetrical, either way is acceptable. We will phase in match marks on the rod and rod caps. Some of the very early en not have these marks. Use a permanent marker if match marks are not visible.

rod can be assembled to the

ines may

2.Several piston and ring combinations have been used. Pistons have been plated and unplated. Pistons have used two keystone rings and others used one semi-keystone and one standard ring. The pistons made for one type of ring will not accept the other type. However, any piston and ring assembly can be used in any cylinder.

Install keystone piston ring in top groove with bevel

facin

up. The square bottom ring can be installed

either way. Note that there are pins in the rin

rooves. The open ends of the rings must line up

with the pins.

3. Assemble ball bearin crankshaft.

4. Note: One side of the paper is sticky; remove paper carefully while installin There should be 32 needle bearin connectin bearin needles to the rod.

5. Install rod cap (A). Ensure that matin ali

ned. Clean old screws (B) thoroughly and apply Loctite 271. (See Fi specifications.

rod. When reinstalling original needle

s, use a little #2 bearing grease to stick the

s to crankshaft and install

needle bearings.

s on the lower

marks are

ure 80.) Torque to

1. Secure wrist pin usin square ed openin Fi

ure 79.)

e of snap ring faces out and ring

faces up (toward top of piston). (See

Figure 79

snap ring. Make sure

0893-028

Figure 80

6.Oil parts. Use ring compressor to install piston with EX mark and arrow pointin exhaust port. Install seals before fully seating the crankshaft. Install new oil seals. Clean seal bore with alcohol before installin may cause the seal to blow out when the engine is hot.

Note: Ring Compressor P/N TOR 4089 (order from OTC, see page 5 for address and phone).

towards the

seals. Oil in the bore

0893-023

Page 52

ENGINE

7. Apply Loctite 515 gasket maker very thinly to the crankcase cover sealin not to

8. Carefully align the two crankcase halves using the ali two halves to

et sealant in bearings. (See Figure 81.)

nment pin (A) and its matching hole. Press the

ether. (See Figure 82.)

surface (A), being careful

ure 81

0720-018

9. Tighten the screws to specifications, tightening only 20 in. lbs. (2.26 Nm) increments at a time while ti

83.)

htening modified (X) pattern. (See Figure

ure 83

0891-005

Reinstalling External Components

10. Reattach the flywheel brake system.

ure 82

1 1. Clean the crankshaft and flywheel hub with alcohol

and install flywheel.

12. Install carburetor and

0720-015

13. Install starter and shroud assembly and starter handle.

14. Reconnect fuel lines and electrical system leads.

15. Install CD pack and set air System on pa

16. Test run en

e 31.

ine.

overnor assembly.

ap. (See Ignition

Page 53

ENGINE

location can be checked after assembly. These seals

installed after the six cap screws are torqued down.

The snap ring on the DureaForce PRO end should be

Crankshaft Seal Replacement

The crankshaft seals on both the R tek and DuraForce engines are located right on top of a groove in the bore

(Figure 85). The rubber on the outer diameter of the seal grips the groove and provides a seal as well as holding the DuraForce engine has a snap ring installed after the seal to help hold it in place (Figure 84). As both the

R tek seals and the DuraForce flywheel seal must set on top of the groove, we do not recommend driving a new seal in place. Driving the seal over the groove would damage the rubber on the outside of the seal.

seal in place. Only the PTO seal on the

Separate the crankcase from the cyclinder to replace the seals. Slide the seals off the crankshaft and clean the case mating surfaces as previously indicated. Clean the block where the seal goes and the outside of the

seal with alcohol to ensure they are oil free. If oil is in the bore or on the seal O.D. the lubrication may cause the seal to move when hot.

Use some type of seal protector to prevent damage to the seal lip and slide the seal down the crankshaft. The seal must rest directly on top of the groove in the block. Seal the crankcase halves as previously indicated. Ensure the seal does not move while assembling the crankcase.

The snap ring on the DuraForce PTO end should be installed after the six cap screws are torqued down. Both R tek seals and DuraForce flywheel end seal

Both R tek seals and the DuraForce flywheel end seal

Figure 8

1657-012

0893-016

should be recessed between .040" and .060" (1.016 -

1.524mm). Check the depth in about 3 places to ensure the seal is at the proper depth and square in the bore.

Page 54

PIVOTING ZONE START BRAKE

gag

PIVOTING ZONE START BRAKE (DuraForce En

Introduction

In 1982, the federal government mandated that all consumer walk behind mowers with a cut of 25" (63.5 cm) or less be equipped with safety devices. There are two primary criteria which these devices must meet:

1. A two-step operation must be performed in order to start the blade rotatin

2. The blade must come to a stop within three seconds of the operator leavin position.

One of the ways the Lawn-Boy Corporation met these requirements was with the “zone start system.” This system utilizes a kill switch and a brake, which stops the en control bail (A). (See Fi en pull the bail to the handle first, then pull the recoil rope from the operator’s position.

ine when the operator releases the blade

ement criteria is met by requiring the operator to

ines Only)

the operator’s

ure 86.) The two-step blade

Operation

The pivoting style zone brake system has two main functions. The first function of the system is to stop the production of spark and the second is to stop the en

ine and the blade. Stoppin The switch is closed when the blade control bail is in

the “at rest” (vertical) position. (See Fi Lowerin switch.

Switch leads are connected to the primary side of the coil and to closed, the electronic i that it cannot interrupt primary current flow. This action prevents the coil from producin necessary to open, the i

spark production is controlled by a switch.

ure 86.)

the bail to the main mower handle opens the

round (see Figure 87). When the switch is

nition module is bypassed so

the high voltage

enerate spark. When the switch is

nition coil produces spark.

Stopping the engine and blade is accomplished by means of a brake that is applied to the flywheel. The brake sprin

ure 86

0893-048

control is in the “at rest” or vertical position. When the blade control bail is lowered to the mower handle, the brake is retracted and allows the en

is in the “braked” position when the blade

ure 87

ine to run.

0893-043

Page 55

PIVOTING ZONE START BRAKE

g g

There are two versions of this brake. The function is the same, but they contact different parts of the flywheel. Fi recoil start en bottom of the flywheel. Fi

htly different system used on electric start engines.

sli On electric start en the side of the flywheel to clear the teeth of the flywheel rin

ear.

ure 88 is a diagram of the system used on

ines. The brake pad engages the

ure 89 is a photo of a

ines, the brake pad must contact

Disassembly

Recoil

Figure 88

3297-023

Electric Start

Figure 89

Note: Numbers in parentheses in the following procedures refer to the previous illustration (see Fi

88).

1. If the en seconds to stop when the blade control bail is released, inspect the brake pad for excessive wear and replace if necessary. Note that the brake pad and the brake plate are replaceable only as an assembly.

ine and blade are taking more than 3

0893-040

ure

1 - Ground strap stop 2 - Self-tappin

screw

3 - Brake switch lead

wire 4 - Ground strap 5 - Insulation strap

6 - Plastic rivet

(self expandin

7 - Shoulder screw

(10 mm) 8 - Brake plate assembly 9-Screw 10 - Brake mountin

) (2)

plate

2. To reduce the pressure of the sprin brake mountin squeeze tabs of brake cable that hold it in place at the brake mountin hole in brake mountin

3. Slide cable out throu mountin cable up throu

Note: In step 4, some units may use a 3/8" head with 1/4" diameter screw (rather than a 10 mm).

4. Remove the 10 mm shoulder screw (7) to remove the brake plate and brake pad attached to it.

5. If the ground strap or any part of this assembly requires replacement, remove the second screw (9) to remove the brake mountin en

ine.

plate (10) and brake plate (8),

plate. Push cable through the

plate.

h horizontal slot in brake

plate. Also, slide the ball end of the

h the vertical slot in the brake plate.

between

plate from the

Page 56

PIVOTING ZONE START BRAKE

Assembly

1. If the brake mounting plate was not removed from the en the push-on terminal directly above the strap stop (4) and continue with the reassembly process.

Note: If the brake mountin ti Nm).

2. Secure the replacement brake plate to the en with shoulder screw (7). Ti (9.2 Nm). Ensure that the brake plate pivots freely .

3. Slide the cable into the narrow slot on the brake mountin hole makin

4. One end of the compression sprin shape to it; that end hooks over an indentation in the brake plate. Squeeze the compression sprin (A) and slip it over the cable between the brake mountin

ine, simply reconnect the grounding lead to

round

plate was removed,

hten screw (9) to 60 - 70 in. lbs. (6.78 - 7.91

ine

hten it to 90 in. lbs.

plate, and then push the cable into the

sure the tabs lock into the bracket.

has a hook

plate and brake plate. (See Figure 90).

6. Operate the blade control bail to verify that the brake mechanism stops within three (3) seconds. There is no adjustment needed after this assembly process is completed. (See Fi

ure 91

ure 91).

0891-1

ure 90

5. Insert the leaded ball end of the cable into the vertical slot (B) of the brake plate. (See Fi

0893-051a

ure 90.)

Page 57

THIS PAGE INTENTIONALLY LEFT BLANK

Page 58

ELECTRIC START SYSTEM (120 VOLT

)

gag

Troubleshooting Starter Motor Fails to Turn

Possible Cause Correction

Power not reachin Starter switch malfunction Check switch usin

ine has seized Verify that the engine turns over freely.

En Starter motor has failed If all the above conditions are checked and the starter still fails to

Introduction

The electric start models of the R tek engine use a 120 volt startin volta to slide out on the shaft and en (See Fi

system. When the starter is supplied with

e, the helical shaft spins forcing the pinion gear

ure 92.)

product Plug another appliance into extension cord to ensure cord is OK.

a volt/ohmmeter set for resistance. Ensure

that there is continuity when the switch is depressed.

turn, it must be repaired or replaced.

Starter Removal

1. Remove the upper housing. Remove the starter

e the ring gear.

switch, the bolt holdin bolts which mount the starter to the en

ure 93.)

the wire clip, and the two

ine. (See

ure 92

120V

ure 93

1657-017

Page 59

ELECTRIC START SYSTEM (120 VOLT)

Starter Disassembly

1. Remove the pinion retaining clip by applying constant pressure towards the end of the shaft on one end of the clip and workin the clip. Always replace clip with a new one.

2. Slide the stop washer, pinion sprin the shaft.

3. Remove the two housin ends from the body. Pay close attention as thin come apart easily when disassemblin

4. The serviceable items are shown. (See Fi

around the rest of

, and pinion off

bolts and separate the

Starter Assembly

Assemble by reversing the disassembly process.

Starter Installation

Install by reversing the removal procedure.

ure 94.)

Figure 94

5. The starter switch is also serviceable. (See Figure

95.) (Note: The wires can be removed by insertin a small diameter drill bit into the holes to release the jaws.)

Figure 95

1657-022

1657-021

Page 60

ELECTRIC START SYSTEM (12 VOLT

)

Troubleshooting Starter Motor Fail to Turn

Possible Cause Correction

Starter motor has failed Check by disconnectin

connector. Apply 12 volts directly to the starter motor. (Note: Due to the connector arran will turn backwards durin

Battery has low char

ine has seized Verify that the engine turns over easily.

En Starter switch malfunction Use a volt/ohmmeter to insure there is continuity in the start

Bad

round Check to ensure the ground is secure and not corroded.

Bad wires between battery and starter Use a volt/ohmmeter to ensure that continuity exists

Introduction

The electric start models of the DuraForce engine utilize a 12 volt startin

• starter motor

• battery

• key switch

• alternator

•re

ulator (cup assembly)

• starter relay

•fuse

e or is disconnected Check battery for full charge and ensure it is connected.

position.

3. Loosen the Allen head bolt used to secure the starter pin with a 1/4” Allen wrench. (See Fi

96.) It may be necessary to remove the carburetor

system consisting of a:

bolts and lower the carburetor to needed clearance for the Allen wrench.

the spark plug wire and starter wiring

ement, it is possible that the starter motor

this test. This does not harm the motor.)

ain access the

ure

Starter Removal

1. Unplug the wiring connector at the starter. Remove the three screws that secure the upper fuel tank/shroud assembly, and move it off to one side. While it is not necessary to disconnect the fuel line, the fuel tank should be nearly empty while workin

2. Remove the two nuts and two bolts that secure the inner shroud/recoil housin side. A assembly from the unit.

on the starting system.

, and move it off to the

ain, it is not necessary to remove the

ure 96

1657-005

Page 61

ELECTRIC START SYSTEM (12 VOLT)

4. Remove the bolt that secures the lower bracket to the chassis. Remove the starter. While removin be careful not to move the starter side to side as you may bend the pinion shaft. (See Fi

ure 97

ure 97.)

1657-004.tif

Starter Testing

1. Connect the red lead of an ohmmeter to the red wire of the starter connector and the black lead of the ohmmeter to the blue wire. Slowly rotate the armature throu the starter acts like a be incorrect.

h 360 degrees. If rotated rapidly,

enerator and readings will

2. Remove the two screws and drag-spring stud (A)

that secure the housin plate. Note that the plate has “OUT” stamped on the top. Durin pinion/clutch assembly.

3. Remove the pinion gear, driven gear and thrust washer. Clean all parts thorou dama

. (See Figure 99.) Remove the cover

e or wear. (See Figure 100.)

ear cover plate to the motor

installation “OUT” must face the

Figure 99

hly and inspect for

1657-016.tif

2. Measure resistance. Readin 10 ohms. If hi resistance) is shown, replace the starter motor.

h resistance or open circuit (infinite

should be less than

Starter Disassembly

1. Slide the pinion/clutch assembly (A) off the pinion shaft. Remove the retainin clutch assembly and disassemble completely. Inspect all parts for wear or dama

as needed. (See Fi

ure 98.)

ring from the pinion/

e and replace

Figure 100

1657-019

Figure 98

1657-020

Page 62

ELECTRIC START SYSTEM (12 VOLT

)

Starter Assembly

1. Apply a light coat of Lawn-Boy “AX” grease to the pinion installation.

2. Place the pinion housin

101.)

3. Place the thrust washer then the driven pin. Make sure the raised side of the driven facin

4. Install the cover plate with the word “OUT” facing the pinion/clutch assembly and secure with two screws and dra replace the dra Torque screws and stud to 20 in. lbs.

ear, thrust washer, and driven gear prior to

ear on small driveshaft in motor

with either side facing up. (See Figure

ear on the

ear is

the cover plate.

ure 101

spring stud. Make sure you

spring stud in its original position.

1657-013.tif

5. Reassemble pinion/clutch assembly . Apply a small amount of Lawn-Boy “AX” the assembly on to the pin with the dra over the stud. (See Fi

rease to the pin. Slide

ure 102.)

ure 102

spring (A)

1657.020

Starter Installation

1. Install the starter leaving the bolts loose.

2. Usin

3. Plu

a feeler gauge, gap the end of the pinion/ clutch assembly away from the en .021” (48 mm to .53 mm). While keepin

ap, tighten the Allen head bolt first, then the lower

mountin

and fuel tank.

bolt.

the wiring connector in and install the shrouds

ine .019” to

this air

Page 63

ELECTRIC START SYSTEM (12 VOLT)

e rate, it is important to use the 120 volt charger

Alternator Introduction

Electric start DuraForce engines are equipped with an alternator to keep the battery “topped off”. The char rate of this alternator is 500 milliamps. Due to the low

char to fully char start of each season. Frequent starts or hard startin may require usin

battery. (See Fi

e the battery before initial use and at the

the 120 volt charger to recharge the

ure 103.)

Note: Fuse - 5 amp, 2 blade automotive.

Figure 103

12v.tif

Page 64

ELECTRIC START SYSTEM (12 VOLT

)

Alternator Output Testing

1. To check output of the alternator accurately, it is necessary to run the en 2900 ± 300 RPM. Readjust the necessary. Refer to pa Governor (DuraForce En

2. With the en connector and reconnect the plu black wires are connected. Usin to read 500 milliamps. Connect the red lead to the red wire the red wire

CAUTION: Keep hands and feet away from the blade.

3. Measure alternator output. The readin from 190-450 M.A. (Milliampere) at 2900 ± 300 RPM. If output is not within specification, check the alternator air

ine running, unplug the battery

oing to the battery and the black lead to

oing to the mower.

ine at operating speed,

overnor if

e 26 (Presetting the

ines Only).

so that only the a multimeter, set

should be

ap.

Alternator Air Gap Adjustment

Alternator Resistance Check

1. Disconnect the electronic cup assembly from the wirin

harness. Connect one ohmmeter (RX-1 scale) lead to the and the other to the en

105.)

2. Measure resistance. The resistance should be from 2.7 to 3.3 ohms. If specification is not met, check resistance at alternator connection. If specification is met at the alternator, look at the harness for breaka alternator connection, replace the alternator.

reen wire of the wiring harness

ine block. (See Figure

e. If specification is not met at

1. Rotate the flywheel until the magnets are directly adjacent to the alternator. There should be a .010” (.25 mm) air

2. If

ap is incorrect, loosen the alternator mounting bolts sli alternator a 75 in. lbs., and recheck the air

104.)

ap.

htly allowing the flywheel magnets to pull

ainst the gauge. Tighten the bolts to

ap. (See Figure

ure 105

0891-004

Cup Assembly Test

1. The cup assembly consists of a capacitor and diode. Its function is to convert alternatin to direct current and increase the volta

2. Disconnect the electronic cup assembly from the wirin

harness. Connect one ohmmeter (RX-1 scale) lead to the connector and the other lead to the red wire of the connector.

reen wire of the cup side of the

current

ure 104

6.tif

Page 65

ELECTRIC START SYSTEM (12 VOLT)

3. Measure resistance. Reverse leads and measure resistance a different resistance between the two measurements — hi opposite way. If specification is not met, replace the cup assembly. (See Fi

ain. The specification is to have

h one way and low the

ure 106.)

Figure 106

0891-003

Toro 38409, 38412, 38413, 38414, 38417 Service Manual

Specifications and Main Features

Frequently Asked Questions

User Manual