Toro 51921, 51920, 51926, 51927 Service Manual

AC-1 ENGINE SERVICE MANUAL

Table of Contents – Page 1 of 2

ABOUT THIS MANUAL

GENERAL INFORMATION ENGINE SPECIFICAT IONS FUEL AND LUBRICATION IGNITION TORQUE SPECIFICATIONS TORQUE SPECIFICATIONS (CONT) SAFETY WARNINGS AND NOTES PRODUCT IDENTIFICATION NUMBERS OIL AND FUEL RECOMMENDATIONS STARTING/STOPPING INSTRUCTIONS SERVICE/MAINTENANCE INSTRUCTIONS STORAGE INSTRUCTIONS

TROUBLESHOOTING ENGINE FAILS TO START ENGINE STARVES ON ACCELERATION ENGINE IS HARD TO START ENGINE STALLS ENGINE FIRES INTERMITTENTLY ENGINE DOES NOT PRODUCE MAXIMUM POWER CARBURETOR FLOODS ENGINE STOPS AFTER RUNNING BRIEFLY ENGINE WILL NOT IDLE ENGINE BACKFIRES OR MISFIRES ENGINE WILL NOT ACCELERATE ENGINE LACKS POWER OR STOPS DURING OPERATION ENGINE VIBRATES EXCESSIVELY ENGINE USES EXCESSIVE AMOUNT OF OIL STARTER ROPE IS DIFFICULT TO PULL OR ENGINE LOCKS

DISASSEMBLY TYPICAL DISASSEMBLY SEQUENCE REMOVE MAJOR COMPONENTS DISASSEMBLE ENG IN E

INSPECTION AND REPAIR CARBURETOR DISA SSEMBLY AND REASSEMBLY STARTER DISASSEMBLY AND REASSEMBLY BREATHER DISASSEMBLY AND REASSEMBLY SPARK ARRESTER SCR EEN PISTON/CONNECTING ROD DISASSEMBLY & ASSEMBLY PISTON/CONNECTING ROD DISASSEMBLY & ASSEMBLY CYLINDER HEAD INSPECTION & REPAIR

AC-1 ENGINE SERVICE MANUAL

Table of Contents – Page 2 of 2

INSPECTION AND REPAIR - Continued CRANKCASE INSPECTION & REPAIR MAJOR COMPONENTS INSPECTION & REPAIR

REASSEMBLY TYPICAL ASSEMBL Y SEQU E NCE ENGINE REASSEMBLY INSTALL AIR FILTER BASE, AIR FILTER AND AIR FILTER COVER ASSEMBLE HANDLE ASSEMBLE COV ERS

ABOUT THIS MANUAL

This Service Manual was written expressly for the Toro AC-1 Four Stroke Engine. The Toro Company has made every effort to make the information in this manual complete and correct. We are hopeful you' find this manual a

If

valuable addition to your service shop.

please contact us at the following address:

you have any questions or comments regarding the information inside,

The Toro Company

Consumer Service Training Department.

81

11

Lyndale Avenue South

!

Bloomington, MN

55420

The Toro Company reserves the right to change product specifications or this manual without notice.

Copyright@

1996

The Toro Company

All

Rights Reserved

General Information

.........................

B

Troubleshooting

Disassembly

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

Reassembly

.........................

..............................

...........................

.#

..

.,

..

.,

..

4

5

Table

Of

Contents

Engine Specifications Fuel and Lubrication

ignition Torque Specifications Safety Warnings And Notes

Product Identification Numbers

Oil And Fuel Recommendations

Starting/stopping Instructions

Service/maintenance Instructions

......................................

Recommended Oil Type Checking the Oil Changing the Oil Recommended Fuel Type

Definition of Blended Fuels Use of Blended Fuels

Use of Fuel Additives

To Start the Engine To Stop the Engine

Air Filter

..................................

...............................

..............................

.............................

............................

...........................

..........................

.........................

..........................

.........................

.

...........................

........................

1-3 1-4 1-4

1-4 1-6 1-7 1-7

1-7

1-8 1-9 1-9 1-9 1-9

1-9

1-10 1-10

1-11 1-11

1-11 Spark Plug Carburetor Adjustment Definition of Optimum Setting for Idle Speed Mixture and

High Speed Mixture Adjustments Rocker Arm to Valve Clearance Adjustment

Spark Arrester Screen

Storage instructions

To Reactivate Unit for Service

Special Tools

...................................

................................

..........................

.....................

...............

..........................

...............................

.......................

1-12 1-12

1-15 1-15 1-16

1-17 1-17

1-18

1

-2

j

Item

B

Engine Type

___

Displacement

~~

~

~~

Air-cooled, 4-Cycle

Stroke

~__~

Average Compression Piston Rings Side Clearance

~~-~___

Top Piston Ring Width Top Piston Ring End Gap Middle Piston Ring Width

_____~.

Middle Piston Ring End Gap

-

~ ~~

Oil Piston Ring Width Oil Piston Ring End Gap

~____

Rocker Arm to Valve Clearance

~~~

~-

-~

~__

-

__~

__~_____--

_-

~~

-

_-

~~~

~

~-

~~

-~

~

__

~~

1

-3

11

Approx Fuel Tank Capacity

TORQUE SPECIFICATIONS

18

oz

(530

ml)

tem

Carburetor/Air Filter Base Plate Mounting Screws

~~~~~

Carburetor Mount Insulator Screws

~~

Clutch Housing/Drum Assembly Screws

_.

~ . ~

_~~_~~~-_____-~_--

-

--~__

~

~ ~~ ~

-

Clutch Rotor Cylinder Head Hex Nuts Cylinder Screws Spark Plug

~

-.

~

-

.

-.

..

_.._..____

. .___

Rear Engine Cover Screw Front Engine Cover Screws

~

.

~~

__

~~

-

1-4

SAFETY WARNINGS AND NOTES

WARNING: Hot Surfaces!

The purpose of safety symbols is to attract your attention to possible dangers. The safety symbols and the explanations with them, deserve your careful attention and understanding. The safety warnings do not by themselves eliminate any danger. The instructions or warnings they give are not substitutes for proper accident prevention measures. Some general warnings follow.

WARNING: Spring Under Tension!

The rope starter on these engines contains a flat wire spring that is under tension. Wear eye and hand protection when replacing worn or broken spring, in case it should uncoil as it is handled. Allow spring tension to be completely relieved and make sure pulley disen-

.

gages from spring before removing the pulley retain-

ers, pulley, and starter spring from housing.

,

WARNING: Electrical Shock!

Never touch electrical wires or components while the engine is running. They can be sources of electrical shock.

The muffler, cylinder, crankcase, trimmer cutting head, and other engine surfaces get extremely hot from operation. These surfaces remain hot for a short period of time after the engine is stopped. To prevent severe burns, allow the engine to cool completely before servicing.

I

WARNING: Explosive Fuel!

Gasoline may be present in the fuel tank, carburetor, fuel lines, or crankcase. Gasoline is extremely flammable and its vapors can explode

if

ignited. Keep sparks, flames, and other sources of ignition away from the engine.

Do

not smoke while servicing the engine. Never

use gasoline as a cleaning agent.

in

not

well-

fill

the fuel

~

Store gasoline only in approved containers, ventilated, unoccupied buildings, away from sparks, flames, or other sources of ignition.

Do

tank while the engine is hot or running, since spilled

fuel could ignite

sparks from ignition. spilled fuel.

if

it comes in contact with hot parts

Do

not start the engine near

Do

not smoke while handling gasoline or

or

filling the fuel tank.

i

.

WARNING: Cracked Or Broken Flywheel Fins Can Become Projectiles!

Be careful not to crack or break any flywheel cooling

fins. They could fly

off

during operation.

If

cooling fin:

are cracked or broken, replace the flywheel.

1

-6

PRODUCT IDENTIFICATION

NUMBERS

When ordering parts, or in any communication involving an engine or product, always give the:

Model Number, and Serial Number

NOTE:

BEFORE Attempting TO START THIS UNIT. Using old oil or fuel can cause engine damage. This type of damage will void the engine warranty

READ

THESE INSTRUCTIONS

CAREFULLY

OR

OPERATE

These numbers are located on a decal (or decals) affixed to the unit (Figure 1-1). The identification de-

will be located on the metal boom. The actual

location will vary depending on the type of product.

Figure 1-1. Product Identification Decal

1.0762.005

.

OIL AND FUEL

RECOMMENDATIONS

Recommended Oil Type

Toro 4-cycle oil is recommended for use in this engine

(Figure 1-2).

high

quality SAE

troleum Institute) service class SG, Using the proper type and weight of oil in the oil pan is

extremely important. Check the oil before each use and change the oil regularly. Failure to use the correct oil, or using dirty oil, can cause premature engine wear and failure.

If

another brand 4-cycle oil is used, use a

30

weight oil of API (American Pe-

SF,

SH.

TORO,

FOUR-CYCLE

ENGINE

OIL

,.

WARNING: Explosive Fuel!

Gasoline can explode if ignited. Store gasoline only in ap-

proved containers, in well-ventilated, unoccupied buildings, away from sparks or flames. Do not fill the fuel tank while the engine is hot or running,

since spilled fuel could ignite if with hot parts or sparks from Ignition. Do not start the engine near spilled fuel. Do not smoke while

handling gasoline. Never use gasoline as a cleaning agent.

Is

extremely flammable and its vapors

it

comes

in

contact

I--------

Figure 1-2. Recommended Oil Type.

3.6051.002

1

-7

Checking the

Oil

The importance of checking and maintaining the

proper oil level in the oil pan cannot be overempha-

sized. Check the oil

1.

Make sure the engine is stopped, level and is cool

so

the oil has had time to. drain into the oil pan

(Figure

1-3

BEFORE EACH USE

as follows:

for straight shaft units or Figure

1-4

for curved shaft units).

1-3.

Figure

2.

To keep dirt, grass clippings, etc. out of the engine, clean the area around the oil

Level Engine - Straight Shaft Unit.

1-4.

Level Engine - Curved Shaft Unit.

fill

plug before remov-

3.6051.020

3.6051.004

ing it.

3.

Remove the oil into the crankcase. Thread the oil

fill

plug; wipe the oil

off.

Reinsert it

fill

plug into the

oil pan.

4.

Remove the oil (Figure

1-5).

fill

plug and check the oil level

Figure

1-5.

Removing Oil Fill Plug.

2.6051.005

The oil level should be up to the top of the dipstick

(Figure

1-5).

Full

(3.40z/lOOml)

Add Oil

L

Figure

5.

1-6.

Oil Level

If

the oil level is low, add the oil to the top

the dipstick (see Figure

3.6051.006

1-6).

Always check the

of

level with the dipstick before adding more oil.

1

-8

Changing the Oil

For a new engine, change the oil after the

hours

every

of operation. Thereafter, change the oil after

25

hours

or before storing the unit for an ex-

tended period of time.

first

10

NOTE:

To prevent extensive engine wear or damage,

always maintain the proper oil level in the crankcase.

Never operate the engine with the oil level below the bottom of the dipstick

Recommended Fuel Type

Change the oil while the engine is still warm. The oil

will flow freely and carry away more impurities.

Change the oil as follows:

1.

Remove the oil

2. Pour the oil into a container by

in a vertical position (Figure

fill

plug.

tipping the trimmer

tipping

7).

Be sure to allow

1-7

ample time for complete drainage. Dispose of oil properly.

Use clean, fresh, regular grade unleaded gasoline less

than

60

days old.

NOTE:

(water). As little as

Alcohol blended fuel absorbs moisture

1

%

moisture in the fuel can cause

fuel to separate and form acids when stored.

If

these types of fuel must be used, use fresh fuel (less

than

60

days old).

Definition

of

Blended Fuels

Today's fuels are often a blend of gasoline and one Or more oxygenates such as ethanol, methanol or MTBE

(ether).

Use of Blended Fuels

If

you choose to use a blended fuel or its use is un-

avoidable, the following precautions are recom-

mended.

1-7.

Figure

Pouring Oil.

3. Fill the oil pan, with 3.4 oz

3.6051.007

(100

ml) of new oil of the

proper type, to the top of the dipstick.

4.

Reinstall the oil

NOTE:

Make sure the O-ring is in place on the oil

fill

plug and tighten securely.

plug when checking and changing the oil.

fill

1.

Always use fresh fuel.

2. Use the special additive Toro Gas Conditioner/ Stabilizer, STA-BIL

(R)

or an equivalent.

3. Drain the fuel tank and run the engine dry before storing the unit.

Use of Fuel Additives

The use of fuel additives, such as Toro Gas Conditioner/Stabilizer, STA-BIL Gas Stabilizer or an equiva- lent, will inhibit corrosion and minimize the formation of gum deposit. Add

0.8

oz (23 ml) per gallon of fuel per instructions on the container. NEVER add fuel ad- ditives directly to the unit's fuel tank. Using a fuel addi-

60

tive can keep fuel fresh for up to

days.

1-9

STARTING/STOPPING

INSTRUCTIONS

To

Start

the Engine

1.

Set the unit on the ground, check the oil level in the oil pan, and put the ignition switch in the “RUN” position (Figure 1-8).

---Run position Partial Choke

choke

(I)

Figure 1-8. Ignition Switch and Throttle Trigger.

2.

FULLY PRESS AND RELEASE the primer bulb 5 to

7

times (Figure 1-9).

NOTE:

For a warm engine, go directly to step

3.6051.008

5

(place the choke lever directly in the “PARTIAL” choke

position).

Figure Positions.

1-9.

Primer Bulb, Choke Lever and Choke

3.6051.009

4.

With the unit on the ground, pull the starter rope quickly until the engine sounds like it wants to run

5

(no more than

pulls) (Fig. 1-10).

,

3.

Place the choke lever

tion (Figure 1-9).

1-10

in

the FULL “CHOKE” posi-

Figure 1-1

0.

Pulling the Starter Rope.

3.6051.010

5.

Place the choke lever in the “PARTIAL” choke position (see Figure 1-9 on page 1.4). Pull the starter rope quickly until the engine starts (no more than

5

pulls).

6.

If

the engine does not start, repeat steps 2 to 8.

7.

Run the engine for

lever fully squeezed (see Figure 1

30

seconds, with the throttle

-6),

to warm up. Place the choke lever in the “RUN” position (Figure 1-9).

2.

Wash the air filter in detergent and water (Figure 1-11). Rinse the air filter thoroughly in clean water and allow

it

to dry.

NOTE:

In colder weather, run the engine for 2 to

3

minutes to warm up.

To

Stop the Engine

Place the ignition switch in the “STOP position (see Figure 1-8).

SERVICE / MAINTENANCE

INSTRUCTIONS

Air Filter

NOTE:

CLEAN AND

EVERY 10 HOURS

one of the most important areas to maintain.

maintained as follows, poor engine performance and

severe engine damage can result.

1. Remove the three filter cover assembly. Remove the air filter cover and air filter. Refer to

RE-OIL

OF

(3)

THE

AIR

FILTER

OPERATION. The air filter is

screws on the carburetor/air

Part

3

-

Engine

Disassembly

\

If

it is not

L

Figure 1-1 1. Washing Air Filter Element.

3.

Apply clean SAE

Figure 1-1

2.

Oiling Air Filter Element.

30

oil to the air filter (Figure 1-12).

3.6051.012

3.6051.011’

I

4. Squeeze the air filter to ensure that the oil is spread throughout the entire filter (Figure 1-13).

1-11

L

Figure 1-13. Squeezing Excess Oil from Air Filter Element.

5.

Spark Plug

3.6051.013

Reinstall the air filter in the carburetor/air filter base. Refer to

Part

5

-

Engine Reassembly

NOTE:

Do not clean the spark plug in a machine

~

which uses abrasive grit. Some grit could remain on

the spark plug and enter the engine causing extensive

damage.

4. Check the spark plug gap using a wire feeler gauge. Set the gap to

5.

Reinstall the spark plug and torque to

(1 1.3-1 2.3

0.025 in

N-m).

(0.635

mm)(Figure 1-14).

100-110 in-lb

Use a Champion RDZ19H spark plug. Every 50

hours

of operation, remove the spark plug, check its condition, and reset the gap or replace with a new plug as

necessary. Allow the engine to cool before removing

the spark plug.

WARNING: Electrical Shock!

Never touch electrical wires or components while the engine is running. They can be sources of electrical

shock.

1. Before removing the spark plug, clean the area around the base of the spark plug to keep dirt and debris out of the engine.

2.

Disconnect the spark plug wire and remove the spark plug from engine.

3.

Inspect the spark plug for carbon buildup and clean

if

necessary. Replace the plug

if

reuse is questionable.

if

it is badly burnt or

Figure 1-14. Spark Plug Gap.

Carburetor Adjustment

3.6051.014

-

These engines are equipped with a diaphragm-type carburetor. The carburetor has been carefully cali-

~

brated at the factory. In most cases, no further adjustment will be required.

The condition of the air filter is very important to the

(

eration of the trimmer. A dirty air filter will restrict the air flow to the carburetor. This in turn upsets the fuelair mixture in the carburetor. The resulting symptoms are often mistaken for an out-of-adjustment carburetor Therefore, check the condition of the air filter before adjusting the carburetor. Refer to “Air Filter“ Service/Maintenance Instructions.

I-

1-12

-

If

the following conditions are experienced, it may be

necessary to adjust the carburetor.

The engine will not idle The engine hesitates or stalls on acceleration. The

loss

of engine power, which is not corrected by cleaning the air filter, muffler, spark arrester screen or adjusting the rocker arm to valve clearance

The engine operates in an erratic or fuel-rich condition

NOTE:

Follow these carburetor adjustment procedures carefully. An incorrectly adjusted carburetor can cause severe engine damage.

407000001-Use the following carburetor adjustment instructions:

1.

Initial Idle Speed Setting:

Turn the idle speed

screw until it stops.

2.

Initial High Speed Mixture and Idle ture Settings:

and idle mixture needles

Turn both the high speed mixture

in (clockwise)

Speed

until they

Mix-

are lightly seated.

3.

Turn the needles

following number

out

of

turns:

the

High Speed Mixture Needle: 1 turn

Idle Speed Mixture Needle:

1

turn

Make sure the unit is fully assembled before

making carburetor adjustments.

For trimmers

and

brushcutters, make sure

the boom, cutting head, and line guard are installed

and the cutting line is extended to its full cutting length.

The carburetor has three basic adjustments: the idle

speed adjustment, the idle speed mixture adjustment, and the high speed mixture adjustment (Figure 1-15).

Mixture Needle

NOTE:

Turn the high speed mixture and idle mixture

needles finger-tight. Do not force the needles with a screwdriver as this can damage the tips of the needles and the seats in the carburetor body.

4. Start the engine and let it run for

3

to 5 minutes

with the throttle lever fully squeezed.

5.

Release the throttle trigger and let the engine idle.

Turn the idle speed screw

until the speed decreases and the bump

wise)

out (counterclock-

head stops rotating.

6.

Final Idle Speed and Mixture Adjustments:

Adjust the idle speed screw and idle speed mixture needle for the smoothest engine idle using

Do

the following procedure.

not squeeze throttle trigger when adjusting the idle speed screw and idle speed mixture needle.

a. Set the idle speed mixture needle

at the optimum setting (Figure 1-16). See “Definition of Optimum Setting” on page

1-1

5.

Figure

1-1

5.

Carburetor Adjustments.

3.6051.015

1-13

b

b. Squeeze the throttle trigger.

falters or hesitates as idle speed mixture needle

wise) 1/16 turn at a time

celerates rapidly.

it

If

the engine

accelerates, turn the

out (counterclock-

until the engine ac-

3.

Turn the needles following number of turns:

High Speed Mixture Needle: 1 1/8 turns

out (counterclockwise)

the

c.

If

the idle speed has changed significantly because of steps a. and b. above, readjust the idle speed screw.

7.

Final High Speed Mixture Setting:

Adjust the high speed mixture needle as follows:

a. Squeeze the throttle trigger and

run the unit at high speed for

b. While squeezing the throttle trigger fully, set

the high speed mixture needle at the optimum setting. See “Definition of Optimum Setting” on page 1-1 5.

NOTE:

must be the last adjustment made the idle speed mixture needle is adjusted, the high speed mixture needle must be readjusted.

8.

For Units with Engine Serial Number 407000001

and Greater-Use

ment instructions:

The high speed mixture needle adjustment

Make sure the air filter cover is reinstalled securely before placing the unit back into service.

the following carburetor adjust-

3

to 5 minutes.

on

the carburetor.

Idle Speed Mixture Needle1 1/8 turns

NOTE:

mixture needles using finger pressure. Forcing the mixture needles will damage the tips of the needles and

the seats in the carburetor body.

4.

5.

6.

If

NOTE:

justment is made, no more high speed mixture needle

adjustments to the carburetor are necessary.

Seat the high speed mixture and idle speed

Start the engine and let it run for 3 to 5 minutes with the throttle lever fully squeezed.

Release the throttle trigger and let the engine idle.

If

the engine stops, turn the idle speed screw

(clockwise) 1/8 turn

the engine idles.

Final High Speed Mixture Needle Adjustment:

a. While squeezing the throttle trigger fully, set

the high speed mixture needle at the optimum setting. See “Definition of Optimum Setting”.

After the final high speed mixture needle ad-

at a time (as required) until

in

~

1.

Initial Idle Speed Setting:

screw (Figure 1-15) it

does not contact

Then turn the screw

gins

to move the throttle lever; then continue turn-

ing

2

full turns.

2.

Initial High Speed Mixture and idle Speed Mixture Settings:

ture and idle speed mixture needles

wise)

until they are

out (counterclockwise)

the carburetor throttle lever.

in (clockwise)

Turn both the high speed mix-

lightly seated.

Back the idle speed

1-14

until it

just be-

in (clock-

until

7.

Final Idle

Adjustments:

idle speed mixture needle for the smoothest engine idle using the following procedure. Do not squeeze the throttle trigger when adjusting the idle speed screw and idle speed mixture needle.

a. Set the idle speed mixture needle at the

b. Turn the idle speed mixture needle

Speed

optimum setting (Figure 1-16). See “Definition’ of Optimum Setting”.

(counterclockwise) 1/8 turn

of optimum.The engine should idle and accelerate smoothly.

and Idle Speed Mixture

Adjust the idle speed screw and

out

to the rich side

’

~

8.

Final Idle Speed Adjustment:

speed by turning the idle speed screw

wise)

or

out (counterclockwise)

head does not rotate.

Do

Adjust the idle

in (clock-

until the cutting

not squeeze the throttle

trigger when adjusting the idle speed screw.

9.

Make sure the air filter cover is reinstalled securely

before placing the unit back into service.

Definition of Optimum Setting for Idle Speed Mixture and High Speed Mixture Adjustments

Always set the idle speed mixture needle and high speed mixture needle at the optimum setting. To find

the optimum setting, use the following procedure.

1. Turn the adjusting needle

out (counterclockwise)

from the preliminary setting until the engine speed

decreases (rich). Note the position of the needle.

2.

Turn the adjusting needle

in (clockwise).

The engine speed may increase as the needle is turned in (lean). Note the position of the needle.

Rocker Arm to Valve Clearance Adjustment

50

hours

Every

of operation, remove the rocker

arm

cover and check the rocker arm to valve clearance.

1.

Remove the four

(4)

screws from the engine cover. Remove the engine cover. Remove the rocker arm cover. Refer to

2.

Position the crankshaft

Part

3

-

Engine Disassembly.

so

that the piston is at the top of the compression stroke (both rocker arms are free and loose).

3.

Measure the clearance between the valve stems and rocker arms, using a

1-17).

flat

feeler gauge (Figure

3.

Set the adjusting needle

midway

and the lean settings (Figure 1-16).

Adjust to

Midpoint

Figure 1-16. Optimum Setting.

3.6051.016

between the rich

Lean

I

Figure 1-17. Measuring the Rocker Arm to Valve

Clearance.

3.6051.017

The recommended rocker arm to valve clearance for both the intake and exhaust is

(.076

mm-,152 mm).

.003-.006

in

4.

If

the clearance is not within specification, adjust as

follows:

Spark Arrester Screen

b

To

the adjusting nut counterclockwise.

To

the adjusting nut

5.

a. Turn the adjusting nut (Figure 1-18), using a

5/16 in (8 mm) wrench or nut driver.

increase the rocker arm to valve clearance,

decrease the rocker arm to valve clearance,

clockwise.

b. Recheck the clearance with a flatfeeler gauge

and readjust as necessary (see Figure 1-1

Reinstall the rocker arm cover, using a new gasket. Torque the rocker arm cover screw to

(2.2-3.4 N.m).

20-30 in-lb

turn

7).

This unit is equipped with a spark arrester screen.

50

hours

Every

screen for debris and/or deposits.

WARNING: Hot Surfaces!

Make sure the muffler is cool before checking the spark arrester screen to prevent injury.

1. Remove the spark arrester cover screw and cover (Figure 1-1

of operation, check the spark arrester

9).

Figure 1-18. Adjusting Nuts.

6. Install the breather hose to the air filter base.

7.

Reinstall the engine cover and screws. Refer to Part

5

-

Engine Reassembly.

Torque the top screws to Torque the front screw to Torque the rear screw with washer to

4.0

Nom).

2.6051.018

15-20 in-lb (1.7-2.2 Nom).

20-25 in-lb (2.2-2.8 Nom).

30-35 in-lb (3.5-

1-16

Figure 1-1

2.

3.

4.

9.

Spark Arrester Screen.

Push the spark arrester screen out of the cover.

Inspect the spark arrester screen.

If

the screen is clean, reinstall the screen, cover and screw. replace it.

Torque the screw to

If

the screen is plugged,

15-20 in-lb (1.7-2.2 N-m).

3.6051.019

STORAGE

WARNING: Explosive Fuel!

Gasoline is extremely flammable and its vapors can explode if ignited. Store gasoline only in approved containers, in well-ventilated, unoccupied buildings, away from sparks or flames. Do not the engine is hot or running, since spilled fuel could

if

ignite from ignition. Do not start the engine near spilled fuel. Do not smoke while handling gasoline. Never use gasoline as a cleaning agent.

1.

2.

3.

it comes in contact with hot parts or sparks

Drain all fuel from the fuel tank.

that has been stored for more than

Start the engine and run it until it stalls. This ensures that all fuel has been drained from the carburetor.

Drain the oil from the crankcase and add fresh oil

(3.4

oz

to lubricate the engine.

INSTRUCTIONS

fill

the fuel tank while

Do

not use fuel

60

/100

ml). Pull the starter rope a few times

days.

Figure

To

1.

2.

3.

1-21.

Storing a Curved Shaft Unit.

Reactivate Unit for Service

Remove the spark plug and drain the oil from the cylinder by slowly pulling the starter rope.

Reinstall the spark plug.

Refuel the unit with fresh gasoline. Start engine in

accordance with the

Starting Instructions.

3.6051.021

4.

Allow the engine to cool. Remove the spark plug and put several drops of any

30

quality SAE

Petroleum Institute) service class SG,

into the cylinder. Pull the starter rope slowly to dis-

tribute the oil. Reinstall the spark plug.

5.

Clean the unit and inspect for any loose or damaged parts. Repair or replace damaged parts and tighten loose screws, nuts, or bolts.

6.

Store the unit in a 'dry, well ventilated area. Place

unit

the for straight shaft units or Figure shaft units).

flat on the floor or on a table (Figure

weight oil of API (American

high

1-21

SF,

for curved

SH

1-20

Figure

1-20.

Storing a Straight Shaft Unit.

3.6051.020

~

Special

Tools

In addition to typical hand tools, the following special

tools are required to properly service this engine:

Clutch Rotor Flywheel Holding

Tool,

P/N 180918 (Figure 1-22).

Tool,

P/N 180919 (Figure 1-23).

0-250 in-lb (0-28.1 N.m) Torque Wrench (Commercially available).

Toro (R)

Screwdriver or Bit Set (Commercially

available).

Two-stroke, Magnetic Pick-up Tachometer

(Commercially available).

Figure 1-23. Flywheel Holding Tool, P/N 18091 9.

3.6051

.023

Figure 1-22. Clutch Rotor

1-1

8

Tool,

P/N 180918.

3.6051.022

General Information

.

...........................

.

Troubleshooting

Disassembly

Inspection and Repair

Reassembly

......

. .

.

...........................

............................

2.

5

2-1

Table

Of

Contents

Engine Fails Engine Starves On Acceleration Engine Engine Stalls Engine Fires Intermittently Engine Does Not Produce Maximum Power Carburetor Engine Stops After Running Briefly Engine Will Not Idle Engine Backfires

Engine Will Not Accelerate Engine Lacks Power Or Stops During Operation

Engine Vibrates Excessively Engine Uses Excessive Amount Of Oil

Starter Rope

Is

Hard

To

Start

...............................

.........................

To

Start

..............................

....................................

.............................

Floods

.................................

........................

................................

Or

Misfires

...........................

............................

...........................

......................

Is

Difficult

To

Pull Or Engine Locks

...................

2-8

.................

2-8

2-9 2-9 2-9

2-3 2-4 2-4

2.5 2-5 2-6 2-6 2-7 2-7 2-7

2-2

c’

When difficulties occur, be sure to check for simple causes which, at first, may seem too obvious to be considered.

A

starting problem, for example, could be

caused by an empty fuel tank. The following table lists some common causes of

operating troubles and the possible causes and

remedies.

I

-

Engine Fails

__

~-

;Possible

L-

Ignition switch in STOP

-~

~_~~~___

~-

~~ ~

Cause

To

.-

~~

_____

Start

~-

_

~.

(0)

position

_

.

~~ ~

-

___

~~

~-__

Out of fuel or water in fuel

~~

-___

Dirty or plugged air filter Loose spark plug lead wire

__~____~

-

.-

~

Fouled, improperly gapped or broken spark plug

__~._

Plugged fuel tank cap vent Plugged or waterlogged fuel filter

-

~_____~

Improperly adjusted carburetor

____-

Plugged muffler

-

Faulty primer or primer/fuel lines improperly installed

~.

-

-.

Plugged fuel line Faulty carburetor diaphragm

____

Plugged spark arrester screen Faulty fuel pump diaphragm

-

~.

_____

~~

.__

~-

-

_____

__

-

Plugged carburetor/fuel pump passages

&

Incorrect air gap between flywheel

ignition module

__

Faulty ignition module

Low

compression

_________~.~

.~

Rocker arm to valve clearance is out of adjustment

_~_____~_

___.

~~ ~~

~.__________

-

~-

~ ~~

-

i

~~ ~ ~

-~

~~~ ~~ ~

~

~-

__

-

__

~~

-_

Remedy

Place switch in

~

RUN

(I)

position

-~~

Drain tank and blow out fuel lines to remove water

Refuel tank with fresh fuel

-_

Clean or replace air filter

Reconnect lead wire

.~____

____

~

___~~

~-____

Clean or replace spark plug; set gap to 0.025 inch

(0.635

Clean fuel tank cap vent

Replace fuel filter

Adjust carburetor

mm)

__

~-

~.-~____-~

~~

__

-~

~-

__

__~-

.-

~-

Clean or replace muffler Correctly install primer/fuel lines or replace primer

~

____~.._~_.________

Blow out fuel line Replace diaphragm

~~

Clean or replace spark arrester screen Replace pump diaphragm

~~~ ~

Clean out passages

__

~.

~~~

-.

~~

.~

~~

~-

~

Set ignition module air gap to

0.008-0.01

-

Replace ignition module

_~_____

Replace piston rings or cylinder

_

2

in (0.201

.-

~~~~

-0.305

__

mm)

~-

--

Adjust rocker arm to valve clearance

___

~ ~~~

~

_

_~_

~_ _~

~-

~ ~

__

-

~ ~~ ~

__

-~

8.

~~ ~

~-

~__

____

~-

~

I-

____

__

I

_~

~-

__

2-3

1

8

Engine

possible

.

Cause

Is

Hard

To

~___~~

Start

~~

Fouled, improperly gapped or broken spark plug

Plugged or waterlogged fuel filter

___.

-

Improperly adjusted carburetor Clogged muffler

~~

Faulty primer or primer/fuel lines improperly installed

~~

Incorrect air gap between flywheel and ignition module

-

Faulty ignition module Plugged spark arrester screen

~-

.~

~

Rocker arm to valve clearance is out of adjustment Worn or improperly adjusted carburetor jet needle Faulty carburetor diaphragm Faulty fuel pump diaphragm

~~

-

~~

__

..

~

.~

-

~~

-

~

-

~.

_____~~~

_____

~

-~

~

________

Low compression

_

-~

~~~~ ~

.

~~~

___

~ ~~ - ~

Remedy

-

~~

~ ~ ~~ ~

Clean or replace spark plug;

~~

set gap to 0.025 inch

~~~

Replace fuel filter

Adjust carburetor

Clean or replace muffler

_-

-

_

~~____~-~

~ ~~ ~ ~~~

~

-~

~

(0.635

mm).

~

Correctly install primer/fuel lines or replace primer

~-

Set ignition module air gap to

0.008-0.01 2 in (0.201 Replace ignition module

___~_~~

Clean or replace spark arrester screen

_____~

~-

~_

Adjust rocker arm to valve clearance

_

Adjust or replace needle

~

Replace carburetor diaphragm

_

-

Replace fuel pump diaphragm

..

~ ~ ~

~~

~~~~~

_

~~ ~

~_-

-0.305

~~

_

~~~ ~ ~

_~

mm)

~ ~

___________~~~

Replace piston rings or cylinder

~

.

_-

~~~

___~_~_____~_~

-.

.

~

-

~-

.~

~

.~

~

_

~~

I

~

-

,

___

~ ~

~

_____

2-4

Engine Stalls

Plugged fuel tank cap vent Improperly adjusted carburetor Plugged muffler Plugged spark arrester screen Plugged fuel line

-

Faulty ignition module

___-

-

__~

~-

~

-~

.~___

~

-_

Clean or replace spark plug; set gap to

0.025

inch

-

-.

~~

(0.635

Clean fuel tank cap vent Adjust carburetor

mm)

~

_.

~-

__

_.

Clean or replace muffler

~

~-

~~ ~~

Clean or replace spark arrester screen

Blow

out fuel line

Replace ignition module

____

~

~-

~

--~

~-

~

-~

__

-___

~

--

-

__~

~-

Engine Fires Intermittently

Fouled, improperly gapped or broken spark plug

____-

incorrect air gap between flywheel and ignition module

improperly adjusted carburetor

~ ~

-~

Faulty ignition module

-

~

__---

Remedy

~ ~~

Clean or replace spark plug; set gap to

0.025

inch

--

~

(0.635

mm).

-~___

Set ignition module air gap to

0.008-0.01

~~

Adjust carburetor

Replace ignition module

~-

~ ~~~

2

in

______~

____

--

(0.201

-.

-

~ ~~ ~

-0.305

~-

__

mm))

-

2-5

,

Engine Does Not Produce Maximum Power

Plugged muffler Plugged spark arrester screen

Plugged or waterlogged fuel filter

-.

..

~

~ ~ ~~~ ~

~~ ~~~~ ~ ~~~

Improperly adjusted carburetor

Air leak at carburetor base gasket

Intermittent spark Low compression

Scored piston and/or cylinder

._

~ ~~ ~

~p

~ ~

..

-

.

Worn piston rings or low compression Cam gear improperly timed

Valves leaking

~~~

~_~

~.

~~

~ _ ~

__

~

Carburetor

Floods

pp~_~

~~~ ~~~

ulty primer or improperly installed primer/fuel lines

_. . .

.

.. . ...

~

11

Damaged carburetor Leaking fuel inlet needle

11

~.

2-6

~~~

~~~~ ~

I

Remedy

.

. .

~_

Engine

_~_____.

possible Cause

i

Stops

~__~~

~~~~

After Running Briefly

-~

~ ~~

Partially plugged fuel tank cap vent Dirty or plugged air filter

Water in fuel

________

~~

Air leak at carburetor base gasket

Dirty carburetor fuel inlet needle or passage

~~

__

Faulty carburetor diaphragm

_______~~

-~

-~__

~

~~

~~___~~~__

Clean or replace air filter

~.

~~

__

Drain tank and blow out lines

~~~~

~~__

Tighten carburetor mounting fasteners or

replace carburetor base gaskets

-

-~

~~ ~

__~_

Replace fuel inlet needle or clean out carburetor

_-.___~.________

~~.~~_____~-

~___~~-~

Replace diaphragm

~

~~

~-

Losing compression

Engine

Possible g Cause

__~

Improperly adjusted carburetor

___~~________

Dirty or plugged air filter Clean or replace air filter Faulty carburetor diaphragm Replace carburetor diaphragm Faulty carburetor inlet seat gasket Replace carburetor inlet seat gasket

Will

~ ~

Not

Idle

~ ~~ ~~ ~~ ~~

~___

~______________~

Leaking crankshaft seal Replace crankshaft seal

Scored cylinder or low compression

____

i

~~1

-_

~ ~ ~

-

.-~.____._~

-$

.__~__

I

Replace piston rings or gaskets or

overhaul engine

___________-__

~~~ ~

~-

Remedy

~~ ~~~ ~~ ~~~ ~~

Adjust carburetor

~~

________

__

~~

~~-.

-~

~ ~

-

.~

-

~__

~____-~

~-

~

~-

~

-

Overhaul engine

--

~-

__

~

Engine Backfires Or Misfires

possible Cause

~

~-

~

Fouled, improperly gapped or broken spark plug

.

.___

Shorted ignition module leads

Rocker arm to valve clearance is out of adjustment

-

Weak valve spring

,__-

~~

-

~. _____.~~

~ ~

___~

~~

~

~-

~~

Check for loose or bare wires or loose assembly and corrector replace ignition module

Adjust rocker arm to valve clearance

-_

-

-~

~___

-

Replace valve spring

~~~~ ~

2-7

Plugged muffler Clean or replace muffler

~

__~~

~___~

Plugged spark arrester screen Carburetor diaphragm gasket leaking

~~

~~__

.

~~__

0.025

inch(0.635 mm)

~

Clean or replace spark arrester screen

~~

.~

~~ ~

.

~~ ~ ~ ~~~~~ ~

Replace gasket

-

~~

Faulty primer bulb causing flooding

Dirty or plugged air filter Plugged muffler Plugged spark arrester screen

~-

Rocker arm to valve clearance is out of adjustment Scored cylinder or low compression (below

. . .

. .

.

-

~

.-.~

-

~~~~~~

~

__~~

~~ ~~~ ~

~

-~

.

~~~____

~~ ~~

~___

~

90

~

psi)

Replace primer bulb

.-

-_

Clean or replace air filter

-

Clean or replace muffler

.

Clean or replace spark arrester screen

-

~

Adjust rocker arm to valve clearance

~~~__

~____._____~~

~~

.-

~ ~ ~~~~ ~ ~ ~

~~~~ ~ ~ ~ ~~

__~

~

~-

-

-~

~~ ~~~ ~

~~ ~~

I

..

Overhaul engine

2-8

I

Oil

fill

plug loose or O-ring is leaking oil

-~

Breather housing plugged or damaged,

___-

..~~

Gaskets damaged or gasket surfaces nicked

-

Valve guides worn excessively

__

..

Cylinder wall worn or glazed

Piston rings and grooves worn excessively

.

.____.

-.

..

Piston fit undersized

~

Starter Rope

Oil

accumulated in combustion chamber

Is

Difficult

To

Pull Or Engine Locks

Replace O-ring and tighten oil

I

~~

Replace

breather housing assembly

__~

fill

plug

smooth gasket surfaces;

~

...

1

Replace cylinder head assembly

~

use new gaskets

~.

Replaced cylinder

piston rings and/or piston

,

1

Measure

-~

~~ ~~~~ ~

~~__-

1.

Remove the spark plug

2.

Drain the oil from the spark plug opening

and replace piston

__~

~~

~____

~~

__~

__

~

~__.~

~_i~~

if

necessary

~ ~~~

3.

Pull the starter rope several times to

remove any excess oil from the cylinder

excess oil with a dry cloth

5.

Reinstall the spark plug

2-9

General Information

. .

.........

Troubleshooting

Disassembly

Inspection and Repair

Reassembly

....

.....

.

.........

.

.........

..........

3

3-1

Table

Of

Contents

Typical Disassembly Sequence

Remove Major Components

Remove Engine Remove The Spark Plug Wire And Spark Plug

Remove Upper Handle

Remove Lower Handle Remove Air Filter Remove Air Filter Base. Primer Bulb And

Carburetor

Remove Primer Bulb Remove Engine Cover Remove Carburetor Mount Insulator Remove Intake Baffle Remove Muffler Remove Clutch Remove Starter Module Assembly

..............................

.................................

...............................

..............................

..........................

...........................

..............

..........................

.............................

...........................

..........................

...................

...........................

....................

3-3 3-4

3-4 3-4

3-4 3-5 3-6

3-6 3-7 3-8

3-8 3-9

3-9 3-10 3-12

Remove Fuel Tank Bracket And Fuel Tank Fuel Tank And Lines Disassembly And Reassembly Fuel Line and Filter Removal Fuel Line and Filter Installation

Disassemble .Engine

Remove Fan Housing

Remove Muffler Baffle Remove Ignition Module Remove Rocker Arm Assembly

Remove Cylinder Head. Valve Assembly And Cylinder

Remove Piston/Connecting rod Remove Cam Bracket Assembly Remove Oil Pan Remove Seal

..................................

................

...........

.......................

......................

...............................

...........................

.........................

......................

.......................

.....................

..............................

...............................

3-13

3-13 3-13 3-13

3-14 3-14

3-14 3-14 3-15

3-17

3-18 3-19 3-19 3-19

3-2

Typical Disassembly Sequence

7.

Remove Engine Cover

This section covers the disassembly of major internal

engine components. covers the disassembly, reassembly, inspection and repair of the subassemblies of the engine components.

Clean all parts thoroughly as the component parts are disassembled. Only clean parts can accurately be inspected and gauged for wear or damage. There are

many commercially available cleaners that will quickly

remove oil and grime from engine parts. When such a cleaner is used, follow the manufacturer's instructions and safety precautions carefully. Particular attention should be given to commercial cleaners compatibility'

with plastic parts.

Make sure that the cleaner is wiped and not allowed to air dry residue on parts which can affect engine lubrication.

The following sequence is suggested for complete engine disassembly. This procedure can be varied toaccommodate individual requirements for disassembly.

Refer to the appropriate parts manual to ensure the

correct replacement parts are ordered.

Part 4 lnspection and Repair

off

of engine parts

as

some cleaners leave a

8. Remove Carburetor Mount Insulator

9. Remove Intake Baffle

10. Remove Muffler

11. Remove Clutch

12. Remove Starter Module Assembly

13. Remove Fuel Tank Bracket and Fuel Tank

14. Fuel Tank Lines Disassembly and Reassembly

15. Remove Fan Housing

16. Remove Muffler Baffle

17. Remove Ignition Module

18. Remove Flywheel

19. Remove Rocker Arm Assembly

20. Remove Cylinder Head, Valve Assembly and Cylinder

1. Drain Fuel from Tank and Oil from Oil Pan

2. Remove Spark Plug Wire and Spark Plug

3. Remove Engine from Equipment

4.

Remove Lower Handle

5.

Remove Air Filter

6. Remove Air Filter Base, Primer Bulb and Carburetor

21. Remove Piston/Connecting Rod

22. Remove Cam Bracket Assembly

23. Remove Oil Pan

24. Remove Seal

NOTE:

necessary to make the desired repairs.

Only disassemble the engine to the extent

3-3

REMOVE

Remove Engine

1.

Drain all fuel from the fuel tank.

MAJOR

COMPONENTS

3

2. Start the engine and allow it to run until it stalls. low the engine to cool.

3.

Drain the oil from the oil pan.

Remove The Spark

1.

Disconnect the spark plug wire from the spark plug. Remove the spark plug

Plug

Wire And Spark

Plug

.

Al-

2.6051.005

Remove Upper Handle

NOTE:

be removed with a T-25 Toro

1.

All

screws are T-25 Toro

Remove the six

(6)

screws from the upper handle.

3-4

(R)

screws and can

(R)

screwdriver.

5

I

REMOVE

(cont.)

I

2.

Separate the the rear of the handle, next to the screw boss

MAJOR

two

halves apart with a screwdriver at the

COMPONENTS

halves

of

the handle by prying

.

NOTE:

handle, making removal

2.6047.026

Remove

-

1.

2.

The anti-vibration isolator

of

the halves difficult.

Lower

Remove the retainer screw, which holds the switch and throttle trigger assembly in the handle. The trigger can now be removed from the cable and the switch lifted cated in the lower handle.

Remove the throttle cable and lead wires from

the lower handle.

Handle

is

wedged into the

off

the

two

pins

lo-

3

E

3.

Press down on the lower handle at the rear, near the isolator. This will dislodge the isolator from the lower handle, allowing the handle to be re-

.

moved.

NOTE:

handle slightly loosen the screws on the fuel tank bracket and pull the fuel tank and bracket away from

the lower handle.

NOTE:

the location and throttle cable location.

If

you have difficulty removing the lower

When removing the lower handle note

of

the anti-rotation cap screw, lead wires

I

3-5

REMOVE MAJOR COMPONENTS

(cont.)

Remove Air Filter

1.

Remove the three cover. Remove the air filter cover

(3)

screws securing the air filter

).

3

NOTE:

position to remove and install the air filter cover.

2.

The choke lever should be in the "PARTIAL"

Remove the air filter element from the air filter

.

The element is held in place by eight

base pins.

(8)

Remove Air Filter Base, Primer Bulb And

Carburetor

1.

Remove the three base, primer bulb and carburetor to the carbure-

tor mount insulator

(3)

screws securing the air filter

).

3-6

2.6047.

REMOVE

MAJOR

COMPONENTS

(cont.)

2.

Remove the Z-bend of the throttle cable from the

hole in the carburetor throttle lever

.

NOTE:

the top of the throttle lever.

3.

4.

5.

6.

The Z-bend is located in the third hole from

Remove the carburetor and the

Dicard the gaskets.

Remove the fuel line from the carburetor fuel inlet

fitting.

Remove the fuel line from the fuel outlet fitting on

carburetor (to primer bulb).

Remove the throttle cable from the carburetor mount insulator.

two

(2)

gaskets.

Remove Primer

1.

Remove the fuel lines from the fittings on the

primer bulb.

2.

Squeeze the mounting tabs on the back of the bulb and pull the bulb out from the front of the air filter base.

3.

Inspect the check valves in the primer bulb for fuel leakage. To do this inspection, place your finger over the long fitting on the back of the primer

.

bulb and press the front of the bulb. collapses and air comes out through the short fit-

ting, replace the primer bulb. Inspect the primer bulb for flexibility and cuts or

tears. Replace the primer bulb

Bulb

If

the bulb

if

necessary

3-7

REMOVE MAJOR COMPONENTS

(cont.)

Remove Engine Cover

1.

Remove the rear engine cover screw

2.

Remove the cover and the screw from the front of the cover. Lift the cover up and

two

(2)

screws from the top of the

off

of the engine.

-

3.6047.035

Remove Carburetor Mount Insulator

1.

Remove the

two

(2)

screws securing the

carburetor mount insulator to the crankcase.

3-8

3.6047.037

REMOVE

MAJOR

COMPONENTS

(cont.)

2.

Remove the carburetor mount insulator and

carburetor mount insulator gasket.

3.

Remove the carburetor mount insulator.

two

(2)

hex nuts on the back of the

2.6047.039

NOTE: For Units Prior to Engine Serial

4050000001-The hex nuts were not retained. Be careful not to lose them.

Remove Intake Baffle

1.

Remove the intake baffle from the cylinder

Number

3

-

Remove muffler

1.

Remove the three

I

(3)

muffler mounting bolts

3-9

REMOVE

MAJOR COMPONENTS

(cont.)

2

Remove the muffler and muffler gasket. Discard

the old gasket.

NOTE:

time.

NOTE:

scrapers. Always use wood or plastic scrapers.

Remove

1.

For units that take attachments, remove the spring.

The muffler baffle cannot be removed at this

Do

not scrape the gasket surfaces with metal

Clutch

Remove the three housing/drum assembly to the fan housing. move the clutch housing/drum assembly

(3)

screws securing the clutch

Re-

2.

Remove the isolator, which clutch cover and the starter module assembly.

3-1

0

is

located between the

2.6047.043

REMOVE MAJOR

COMPONENTS

(cont.)

I

3.

With the starter pawls on the flywheel positioned at the top (12 o'clock) and bottom stall flywheel holding tool, P/N 18091 9.

4.

Lift the starter assembly until rotor. At 9 o'clock on the fan housing, roll the flywheel holding tool into the flywheel until the head of the cap screw on the bottom of the tool fits into the screw hole of the fan housing.

(6

o'clock), in-

it

contacts the clutch

5.

Holding the flywheel holding tool in place, postion the clutch rotor tool (P/N 180918) over the rotor.

REMOVE

MAJOR

COMPONENTS

(cont.)

6.

Using a rotor tool counterclockwise to remove the clutch rotor.

7.

Remove the clutch rotor and washer.

3/4

inch socket wrench, turn the clutch

-~

2.6047.M

Remove Starter Module Assembly

1.

Remove the rope eyelet bracket. Remove the starter module assembly.

3-1

2

two

(2)

screws securing the starter

REMOVE MAJOR

(cont.)

COMPONENTS

Remove Fuel Tank Bracket And Fuel Tank

1.

Remove the bracket.

2.

Remove the fuel tank bracket and fuel tank.

3.

Remove the rubber fuel tank pad.

two

(2)

screws from the fuel tank

'

3

Fuel Tank And Lines Disassembly And Reassembly

Fuel Line and Filter Removal

This unit has clear line provides normal fuel flow. The blue line provides a return line for excess fuel flow during the primer operation.

1.

Push the fuel line into the fuel tank until you can pull the filter out of the tank neck.

two

fuel lines to the fuel tank. The

2.

If

the fuel filter is dirty or clogged, replace it with a

new fuel line assembly.

Fuel Line and Filter Installation

1.

Insert a piece of trimmer line through the hole in the rear side of the fuel tank to the filler opening. Slide the fuel line over the trimmer line.

2.

Guide the fuel line through the hole in the tank with the trimmer line.

3.

Working through the filler neck, insert the fuel line with the fuel filter attached through the hole in the rear of the tank.

4.

Work the fuel line from outside of tank, pulling until the filter lays on the bottom of the tank or inches

(1

52

mm) of line are exposed.

6

3-1

3

DISASSEMBLE ENGINE

Remove Fan Housing

1.

Remove the four housing to the crankcase. Remove the fan hous-

ing.

2.

Disconnect the switch lead wires.

Remove Muffler Baffle

1.

Remove the muffler baffle.

(4)

screws securing the fan

53

Remove Ignition Module

1.

Remove the

two

(2)

screws securing the ignition module to the crankcase. Remove the ignition module.

3-1

4

DISASSEMBLE ENGINE

(cont.)

WARNING:

CRACKED

OR

BROKEN COOLING

FINS ARE A HAZARD! Be careful not to crack or

off

break any cooling fins. They could fly

eration.

If

cooling fins are cracked or broken, re-

during op-

place the flywheel.

1.

Remove the spacer from the crankshaft.

2.

Using a plastic-faced mallet, tap and pull the fly-

~

wheel until it breaks free from the crankshaft.

3.

Remove the flywheel from the crankshaft.

4.

Remove the flywheel key from the crankshaft.

~

I

Remove Rocker Arm Assembly

1.

Remove the rocker arm cover screw. Remove rocker arm cover and gasket.

I

3.6047.058

I

3-1

5

DISASSEMBLE ENGINE

2.

Remove the rocker adjusting nuts, rocker arm

pivots and rocker arms.

(cont.)

Adjusting Nut

Arm

NOTE:

disassembling the rocker arm assembly.

3.

I

4.

Always match intake and exhaust parts when

Remove the

guides.

Remove the four

washers.

two

(2)

push rods from the push rod

(4)

cylinder hex nuts and

Rocker Arm

5.

Remove the push rod guides from the cylinder

studs.

3-1

6

2.6060.060

2.6047.061

DISASSEMBLE ENGINE

Remove Cylinder Head, Valve assembly And Cylinder

1.

Lift the cylinder head

the cylinder head gasket.

2.

Remove the two from the cylinder head.

off

of the cylinder. Remove

(2)

valves and valve retainers

(cont.)

NOTE:

down on the valve retainers with your fingers and

rock them to the side.

3.

NOTE:

necessary.

NOTE:

should not be removed from the cylinder head,

To

make removal of the valves easier, push

Remove the

The valves cannot be ground. Replace

The rocker box is factory assembled and

two

(2)

valve springs.

I

DISASSEMBLE

I

4.

Remove the two

cylinder.

ENGINE

(2)

cylinder screws from the

(cont.)

5.

Remove the cylinder and cylinder gasket from the

crankcase.

NOTE:

To

Do

not scrape the gasket from the cylinder.

remove the gasket, soak the cylinder with solvent.

L

2.6047.065

2.6047.066

Remove

1.

Piston/connecting

rod

Remove the piston/connecting rod from the crankcase. Grasp the piston/connecting rod, slide it to

the rear and twist slightly. No tool

3-1

8

is

required.

DISASSEMBLE

-

Remove Cam Bracket Assembly

1.

Remove the assembly. Remove the cam bracket assembly.

two

ENGINE

(2)

screws from the cam bracket

(cont.)

Remove

1.

Remove Seal

NOTE:

he crankcase.

1.

Oil

Pan

Remove the six

move the oil pan.

Remove the seal only

Remove the seal from the flywheel side

crankcase, using a seal puller or flathead screw-

driver.

(6)

screws from the oil pan. Re-

if

oil

is leaking from

Of

the

NOTE:

crankcase.

Do

not remove the crankshaft from th6

3-1

9

General Information ...............

*.

.

I.

Troubleshooting

Disassembly

Inspection and Repair

Reassembly

.................

..................

...................

.............

..

.

..

//

!!

l1

Table

Carburetor Disassembly And Reassembly

Carburetor Disassembly Fuel Metering Side

Fuel Pump Side Carburetor Inspection and Cleaning Carburetor Reassembly

Fuel Metering Side

Fuel Pump Side Final Carburetor Adjustment

Adding Starter Spring Tension Starter Disassembly Starter Inspection and Service

Starter Reassembly

Breather Disassembly And Reassembly

Breather Hose Function Test

.............................

..............................

............................

Of

.........................

..........................

........

.......................

Contents

....................

...................

i

..............

......................

.....................

4-3 4-3

4-4 4-5

4-5 4-6

4-6 4-9

4-9

4-10 4-11 4-12

4-13

4-15

4-16

I

~

I

~

I

~

Reassembly

Spark Arrester Screen

Piston/Connecting Rod Disassembly & Assembly

Piston Inspection and Repair Connecting Rod Inspection and Repair Reassembly

Cylinder Head Inspection & Repair

Cylinder Inspection and Repair Valve Assembly. Inspection and Repair Crankcase Inspection and Repair

Crankcase Inspection Cam Bracket Disassembly and Inspection

Cam Bracket Reassembly

Major Component Inspection

Fuel Tank and Cap Inspection Clutch Inspection 4-22

Muffler Inspection and Cleaning

................................

..............................

.......................

..................

................................

........................

......................

..................

.....................

............................

........................

&

Repair

......................

.......................

.............................

......................

4-16 4-16

................

..

4-17 4-17

4-18 4-18

4-19

4-19 4-20 4-20

4-20 4-21

4-21 4-22

4-22

4-2

Flywheel Inspection and Repair

......................

4-23

I

This section covers the disassembly, reassembly, inspection and repair of the subassemblies of the major internal engine components.

Clean all parts thoroughly as the component parts are disassembled. Only clean parts can accurately be in-

spected and gauged for wear or damage. There are many commercially available cleaners that will quickly re-

move oil and grime from engine parts. When such a cleaner is used, follow the manufacturer’s instructions and safety precautions carefully. Particular attention should be given to commercial cleaners compatibility with plastic parts.

is

wiped

off

Make sure that the cleaner

of the engine parts and not allowed to air dry as some cleaners leave a

residue on parts which can affect engine lubrication.

CARBURETOR DISASSEMBLY’

AND REASSEMBLY

Carburetor

The fast idle starting system consists

Disassembly

of

a throttle cam, which is activated by a choke cam. When the cams are in the choke position, it

is

not necessary

to

squeeze the throttle fully when starting, which reduces the likelihood of flooding.

1.

Inspect throttle and choke cams for wear age. Replace,

2.

Remove the high speed mixture

(L)

ture

if

necessary.

adjusting needles and springs.

(H)

or

dam-

and idle mix-

-

~

4-3

2.

Remove the fuel metering diaphragm and gasket.

2.6047.074

NOTE:

These components are under spring tension. Remove them carefully to prevent sure the spring is not stretched.

4-4

loss.

Make

CARBURETOR DISASSEMBLY AND REASSEMBLY

(cont.)

...

Fuel Pump Side

1.

Remove the idle speed adjusting screw and spring from the fuel pump cover.

2.

Remove the fuel pump cover screw and cover

,

Idle Speed

Adjusting Screw

ring

3.

Remove the spring, fuel pump cover gasket pump diaphragm from the fuel pump cover.

NOTE:

throttle plate, throttle lever, choke lever, welch plugs, fuel inlet screen, etc. is not recommended.

/-

NOTE:

do not use drill bits or wire to clean fuel ports and passages.

Further disassembly to remove the

To prevent damage to the carburetor body,

I

4

and

Carburetor Inspection and Cleaning

Two carburetor service kits are available: a gasket/diaphragm kit and a carburetor repair kit.

The gasket/diaphragm kit contains the fuel metering cover gasket, fuel metering diaphragm, fuel pump cover gasket, and fuel pump diaphragm.

The carburetor repair kit contains the gaskets and diaphragms included in the gasket/diaphragm kit plus fuel inlet needle and spring, fuel metering

lever, metering lever hinge pin, the fuel inlet screen

CARBURETOR DISASSEMBLY AND

REASSEMBLY

Refer to the appropriate parts manual for service kit part numbers.

1.

Inspect the tips of the high speed mixture needle,

idle speed mixture needle, and fuel inlet needle for wear or damage. Replace the needles essary.

(cont.)

if

nec-

Inspect Here

4

2.

Gaskets and diaphragms eventually deteriorate

and become stiff with age and use.

practice to replace gaskets and diaphragms for each repair. However,

and flexible, you do not need to replace it, un-

less a complete carburetor rebuild is being per-

formed.

3.

Clean the metering cover, pump cover, carburetor body and filter screen with carburetor cleaner. Blow out all passages with compressed air.

Carburetor Reassembly

Fuel Metering Side

1.

Install the fuel inlet needle, fuel metering lever

spring, metering lever and metering lever hinge

pin. Secure the hinge pin in carburetor body with

the hinge pin screw.

if

the diaphragm is

It

is good

soft

I I

1

4-6

2.6047.078

CARBURETOR DISASSEMBLY AND REASSEMBLY(cont.)

2.

Place a straight edge across the carburetor body. Use a

wire

feeler gauge to measure the distance between the straight edge and the top of the fuel metering lever.

DEPRESS HERE

HIGH

THEN

NEEDLE

HERE

PUSH

LOW

3.6047.079

The fuel metering lever should be

in.

(1.52-1.78

If

the lever is adjusted too high, the engine will

run rich. gine will run lean. Poor acceleration and erratic operation may also be noted.

mm)

below the straight edge.

If

the lever is adjusted too low, the en-

0.060-0.070

2.6047.081

3.

Install the metering cover gasket (next to carburetor body) and metering diaphragm. Make sure the larger circular plate of diaphragm is towards the metering lever.

CARBURETOR DISASSEMBLY AND REASSEMBLY(cont.)

4.

Make sure there are no wrinkles in the metering diaphragm. Install the metering cover and screws. Tighten the screws securely.

5.

Install the high speed mixture (H) and idle mixture

(L)

adjusting needles and springs.

2.6047.082

.Turn both needles

lightly

are

seated.

out (counterclockwise)

in (clockwise)

until they

Then turn the needles

the following

number of turns:

For Units with Engine Serial Number Prior to

407000001

High Speed Mixture Needle: Idle Speed Mixture Needle:

1 turn 1 turn

For Units with Engine Serial Number 407000001 and Greater-

High Speed Mixture Needle: Idle Speed Mixture Needle:

NOTE:

needles

Turn the high speed mixture and idle mixture

finger-tight.

Do

not force the needles with a

1 1/8 turns 1

1/8

turns

screwdriver because this can damage the tips of the needles and the seats in the carburetor body.

Idle speed

2.6047.083

.

3.6051.015

4-8

CARBURETOR DISASSEMBLY’ AND REASSEMBLY

Fuel Pump Side

-

1.

Install the fuel pump diaphragm (next to

carburetor body) and gasket.

2.

Install the spring, fuel pump cover, and cover screw. Tighten the screw securely.

(cont.)

-

~

2.6047.0

3.

If

necessary, install the idle speed adjusting screw

and spring.

For Units with Engine Serial Number and Greaterwise)

until it

tinue turning

Turn the adjusting screw

just

touches

2

full turns.

the throttle lever; then con-

Final Carburetor Adjustment

407000001

in

(clock-

~

Make final adjustments to the carburetor when ,the unit

is

fully reassembled. Refer to “Carburetor

Adjustment” in

Part

I

-

General

Information.

STARTER DISASSEMBLY AND

REASSEMBLY

WARNING:

The rope starter on these engines contains

a flat wire spring that is under tension.Wear eye and hand protection when replacing a worn or broken spring, in case it should uncoil as it is handled. Allow spring tension to be completely relieved and make sure the pulley disengages from spring before removing the pulley retainers, pulley, and starter spring from housing.

1.

Holding the pulley in place, remove the

screws and retainers from the starter housing.

2.

Wind one or more extra turns pulley.

Spring under tension!

of

rope onto the

two

2.6060.153

(2)

3.

Replace the retainers and screws.

NOTE:

(2.3-3.4

pulley.

4.

NOTE:

necessary to make the pull handle return against the starter housing. Adding excessive spring tension can

cause the spring to break.

and adjustment will not enable the pull handle to return against the starter housing, replace the spring.

Torque the retainer screw to

N.m)

after additional rope is wound onto the

Pull the rope out to its full length and let it return until the pull handle rests against the starter housing.

Do

not add any more tension than is

If

spring pressure is weak

20-30

in-lb

4-1

0

STARTER DISASSEMBLY AND

REASSEMBLY

(cont.)

Starter

1.

2.

I

2.8047.088

3.

Starter Pulley

Disassembly

Relieve the spring tension by removing the' pull handle and allowing the pulley to inside the starter pulley. Make sure the spring tension is

Remove the

Remove the starter pulley from the starter

housing.

fully

two

relieved

before proceeding.

(2)

screws and retainers.

slow/y

unwind

Retainer

Retainer Screw

4.

If

necessary, remove the starter spring from the

starter housing.

NOTE:

starter spring, drop the spring into a trash container, which will release the spring from the housing.

NOTE:

the starter housing, a service replacement spring (prewound and contained in a spring retainer) should be used to reassemble the starter. Reinstallation of the old starter spring

To

prevent injury when removing the

Once the starter spring is removed from

is

not recommended.

STARTER DISASSEMBLY AND REASSEMBLY

5.

Remove the starter rope from the pulley.

(cont.)

NOTE:

the production of the equipped with

Starter Inspection and Service

1.

2.

Two types of starter pulleys were used in

AC-1

engine. Your unit is

one

of

the starter pulleys shown.

Inspect the starter rope for wear or frays. Replace the rope

Inspect the starter pulley for worn pawl engagement teeth.

of pulley that

if

necessary.

Also

check for wear on the surface

is

in contact with the starter spring.

E

3.

Make sure old grease and dirt are cleaned from

all starter components before reassembling.

4-1

2

STARTER DISASSEMBLY AND

REASSEMBLY

Starter Reassembly

1.

Install the starter spring into the starter housing as follows:

a. Orient the replacement starter

spring

b.

Grasp the spring near the spring hook with a needle-nose pliers and move the spring retainer.

so

the spring windings are

(the open end

(cont.)

of

spring hook

clockwise

is

to the left).

carefully

~

re-

c. Place the spring into the starter

housing. Make sure the spring hook is installed into the groove of the starter housing.

d. Make sure the spring windings are

laying flat against the starter housing around the entire circumference of the spring. Hold the

spring in this position and

needle-nose pliers holding the spring.

2.

Insert the rope through the hole in the starter pulley. Tie a single knot in the rope approximately

0.5

in.

(12.7

mm)

from the end.

carefully

release the

4.

Hold the pulley with the pawl engagement teeth towards you. Wrap the rope around the pulley in the clockwise direction. Make sure

all

of

rope is wound onto the pulley.

2.6047.089

r

the

2.6060.156

Apply a small amount

5.

of

grease (Mobilgrease

(R) or equivalent) to the post in the starter housing, spring, and the backside

Install the rope guide eyelet onto the starter rope.

6.

Place the rope through the eyelet. Install the pull

7.

of

the pulley.

handle on the rope and secure it with a single knot.

4-1

4

HP

2.6065.157

STARTER DISASSEMBLY AND,

REASSEMBLY

8.

Install the pulley/rope assembly into the starter housing. Rotate the pulley slightly until the spring hooks onto the pulley and the-pulley drops ‘into place.

9.

Holding the pulley down, put tension on the pulley.

10.

Install the

Torque the screws to

two

(cont.)

1

full turn

(2)

pulley retainers and screws.

20-30 in-lb (2.3-3.4

of

N-m)

Spring

I

11.

Pull the rope out to its full length and

let

it

return. Check the spring tension and adjust as necessary. Refer to “Adding Starter Spring Tension” on page

4-1

0

for the location of the

starter rope.

2.6047.086

BREATHER DISASSEMBLY AND

REASSEMBLY

”

1.

.

Remove the breather hose assembly from the rocker arm cover.

Breather Hose

2

Remove the breather hose from the breather housing/plug.

Plug

4-1

5

BREATHER DISASSEMBLY AND REASSEMBLY

Breather Hose Function Test

1.

Test the hose by attempting to blow air through it in both directions. air should flow only in the direction shown (out

1.

Install the breather housing/plug into the hose.

2.

Slide the breather hose assembly, from the inside out, into the rocker arm cover until the breather hose seats into the cover.

(cont.)

of

the crankcase).

2.6060.159

SPARK ARRESTER SCREEN

1.

Remove the spark arrester screw and cover.

2.

Push the spark arrester screen out of the cover.

3.

Inspect the spark arrester screen.

If

the screen is clean, reinstall the screen, cover and screw. clean or replace.

4-1

6

If

the screen is plugged,

Spark Arrester.

3.6047.096

PISTON/CONNECTING ROD

&

DISASSEMBLY

1.

Remove the three piston/connecting rod.

2.

Remove the wrist pin buttons, wrist pin and

connecting rod from the piston.

ASSEMBLY

(3)

piston rings from the

-

Piston Inspection and Repair

1.

Inspect the piston and piston rings for wear and damage. Refer to the specifications and tolerances in

Replace the piston and piston rings

2.

Inspect the ring grooves on the piston for carbon deposits. Clean the ring grooves thoroughly with an old broken ring.

Part

1

-

General Information.

if

necessary.

4-1

7

PISTON/CONNECTING

ROD

DISASSEMBLY & ASSEMBLY

3.

Check the side clearance of the piston rings. The maximum side clearance is

(0.1

27

mm).

Connecting Rod Inspection and

Repair

.005

inch

(cont.)

2.6047.100

1.

Check the bearing area (lower end) for excessive

wear, score marks, running and side clearances.

Refer to the specifications and tolerances in

Part

1

-

General Information.

connecting rod

Reassembly

1.

Install the piston rings into the ring grooves in the

piston.

if

necessary.

Replace the

RING

PLACEMENT

TOP

Compression Ring

MIDDLE

Compression/

Scraper ring

BOTTOM

Oil Control Ring

RING GAP ORIENTATION

PISTON/CONNECTING ROD DISASSEMBLY

Orient the piston ring gaps as shown

&

ASSEMBLY

To Top Ring

Middle

180

Degrees

To Top

Piston

Wrist Pin

Button

ling

Ring

Degrees Ring

Ring

3.6047.102

2.

Install the connecting rod, wrist pin buttons and

wrist pin into the piston.

NOTE:

the recess of the button facing the piston.

Make sure the buttons are installed with

CYLINDER HEAD INSPECTION REPAIR

Cylinder Inspection and Repair

1.

Check all gasket surfaces free of debris. Gasket surfaces must also be free

of

deep scratches or nicks.

2.

Inspect the cylinder and cylinder head for wear and damage.

3.

Inspect the intake port of the cylinder head for

if

blockage. Clean

4.

Inspect and clean the “EGR” (Exhaust Gas Recirculation) hole, which is located between the exhaust and intake ports.

necessary.

to

make sure they are

&

4-1

9

CYLINDER HEAD INSPECTION

&

REPAIR

Valve Assembly Inspection and Repair

I.

Inspect the valve springs and related hardware for

excessive wear or distortion.

2.

Check the valves and valve seat area for evidence of deep pitting, cracks, or distortion. Check the clearance of the valve stems in the guides.

NOTE:

by high fuel consumption may be symptoms of faulty valves. Although these symptoms could also be attrib- uted to worn rings, remove and check the valves first.

3.

Difficult starting or

Check the valve guides for excessive wear.

If

a valve guide is worn beyond specifications, it will not guide the valve in a straight line. This may result in burnt valve faces or seats, compression and excessive oil consumption. Replace cylinder head,

(cont.)

loss

of power accompanied

if

necessary.

loss

of

2.6047.118

CRANKCASE INSPECTION

&

REPAIR

Crankcase Inspection

1.

Inspect the crankcase for nicks, cracks, and

deformation. Replace,

2.

Inspect the crankshaft for nicks, cracks, roundness and deformation. Replace,

necessary.

4-20

if

necessary.

if

2,8047,109

CRANKCASE INSPECTION

&

REPAIR

(cont.)

Cam

Bracket Cam

Cam Bracket Disassembly and Inspection

1.

Disassemble the cam gear, two bracket

2.

Inspect the cam gear, bracket, and followers for

wear or damage. Replace any or all of the parts

if

3.

Inspect the teeth on the cam gear. badly worn, chipped or missing, replace the cam gear.

,106

Cam Bracket Reassembly

1.

Make sure you have all of the necessary parts to reassemble the cam bracket assembly.

2.

Install the cam followers to the cam bracket.

.

necessary.

(2)

followers and

If

the teeth are

-

NOTE:

to the end of the bracket with the step on it.

3.

Make sure the cam followers are installed

Install the cam gear to the cam followers and bracket.

4-21

MAJOR COMPONENTS INSPECTION

&

REPAIR

Fuel Tank and Cap Inspection

1.

Inspect the fuel tank for cracks, rubbing, or chaffed spots. Replace the tank

2.

Inspect the rubber fuel tank mounting pad for

condition. Replace the pad

3.

Inspect the fuel tank cap for cracks, damaged vent valve, or other visible signs of damage. Replace the cap

Clutch Inspection

if

necessary.

if

necessary.

if

necessary.

1.

Check the clutch rotor for wear or damage. Replace,

Muffler Inspection and Cleaning

The muffler should be removed periodically to inspect

for excessive carbon build-up. Excessive deposits

around the exhaust port will cause poor engine performance.

If

carbon build-up cannot be cleaned, replace the

muffler. Inspect the muffler mounting holes for elongation.

Replace the muffler

if

necessary.

if

the holes are elongated.

2.8080.162

4-22

2.8047.125

I

MAJOR COMPONENTS

INSPECTION

&

REPAIR

(cont.)

CONTENTS

#180142

2 Starter Pawl Pins

(oversized)

OF

KIT

2.6060.1

Flywheel

Inspect the flywheel for the following conditions:

Miissing, broken or cracked fins.

Oval shaped pawl pin holes.

Broken, damaged or missing springs, pawls or

pawl pins. Freedom of movement of pawls. Evidence that the Starter Pawl Repair Kit has

been installed (holes in bottom of the flywheel below pawl pins).Engine

Other signs of fatigue, wear or damage

flywheel.

Starter Pawl Repair Kit, P/N 180142, is available to repair the flywheel. This kit contains (oversized*), pawls.

(5.79

tion instructions are provided in the kit.

Inspection

two

To

install the kit, an arbor press, 0.228 inch

mm) drill and drill press are required. Installa-

and

Repair

2

(2) pawl springs, and

to

the

pawl pins

two

(2)

NOTE:

Once this kit is installed, the flywheel cannot be repaired a second time.

The pawl pins in this kit are oversized.

General Information

......................

Troubleshooting

Disassembly

Inspection and Repair

Reassembly

.........................

..........................

...........................

.....................

I

Table

Of

Contents

Typical Assembly Sequence

Engine Reassembly

Install Seal Install Cam Bracket Assembly Install Piston/Connecting Rod Install Cylinder Install Oil Pan Cylinder Head Assembly Install Rocker Arm Assembly Rocker Arm to Valve Clearance Adjustment Install Spark Plug Install Muffler Install Intake Baffle

i

Install Carburetor Mount Insulator

.............................

..............................

............................

.............................

........................

....................

.......................

....................

.............

............................

..........................

..................

5-3 5-4 5-4 5-4

5-5

5-6

5-7

5-8

5-10

5-11

5-12

5-13

5-13 Install Ignition Module Install Fan Housing Install Fuel Tank And Fuel Tank Bracket Install Starter Module Assembly Install Clutch Install Primer Bulb. Carburetor And Connect Fuel Line Install Air Filter Base. Air Filter and Air Filter Cover

Assemble Handle

Install Lower Handle

Install Upper Handle

Assemble Covers

Install Engine Cover

........................

.........................

...............

...................

.............................

.......

.........

..............................

.........................

..............................

.........................

5-14

5-15 5-15

5-15

5-16

5-17

5-18 5-20 5-20 5-21 5-23

5-23

5-2

The following sequence is suggested for complete en-

gine reassembly. This procedure assumes that all com-

or

ponents are new component subassembly work has been completed. This procedure can be varied to accommodate individual requirements for assembly.

NOTE:

specified torque values and clearances. Failure to observe specifications can cause severe engine wear or damage.

Make sure the engine is assembled using all

have been reconditioned, and all

10.

11.

12.

13.

14.

15.

Install Muffler1

Install Intake Baffle Install Carburetor Mount Insulator Install Flywheel Install Ignition Module Install Fan Housing

No

contaminants or debris should be on the parts

when reassembling.

Always

use

new

gaskets.

Typical assembly sequence

1. Install Seal

2. Install Cam Bracket Assembly

3.

4.

5.

6.

7. Install Rocker Arm Assembly

8. Rocker Arm to Valve Clearance

9.

Install Piston/Connecting Rod Install Cylinder Install Oil Pan

Cylinder Head Assembly

Install Spark Plug

16.

17.

18.

19.

20.

21.

22.

23.

24.

Install Fuel Tank and Fuel Tank Bracket install Starter Module Assembly

Install Clutch Install Primer Bulb, Carburetor, and Connect

Fuel Lines Install Air Filter Base, Air Filter and Air Filter

Cover Install Lower Handle Install Upper Handle Install Engine Cover Prepare Unit for Operation

ENGINE REASSEMBLY

Install Seal

1.

If

the seal was removed in

press a

flush with the crankcase surface

metal surface facing out).

new

seal into the crankcase until it is

Part

3

-

Disassembly,

(with the

5

NOTE: To

grease the inner ring of the seal with Mobilgrease (R)

Install Cam Bracket Assembly

1.

Rotate the crankshaft until the crankpin is at top

dead center between the timing marks

make the installation of the seal easier,

HP

or an equivalent.

2.6047.109

2.

Slide the cam bracket assembly into the crankcase with the open hole down

(6

o’clock) and the blocked hole at the top

(1

2

o’clock).

of

the cam gear

2.6047.110

5-4

I

ENGINE ASSEMBLY

(cont)

Make sure the line below the blocked hole, cam gear is parallel to the crankcase without turning the engine.

3.

Install the

crankcase with the

Torque the screws to

cam

bracket assembly into the

two

(2)

screws.

15-20 in-lb (1.7-2.2

of

the

N-m).

TOP

I

2.6047.112

Install Piston/connecting

1.

Make sure the piston rings are installed correctly

as shown.

Rod

5-5

ENGINE ASSEMBLY

2.

Orient the ring gaps as shown

(cont)

r-

Top

Ring

45

Deg.

CCW

To

.

RING GAP ORIENTATION

3.

Install the piston/connecting rod assembly into

the crankcase with the lettering on the bearing

of

the connecting rod facing the crankshaft counterweight. Slide Angle it slightly and roll it into place. Be sure not to dislodge the wrist pin buttons.

it

down in the crankcase.

Bottom

90

Deg. CCW

To

Top

I

Ring

Wrist Pin Axis

Middle

180

Deg.

CCW To

Ring

Top

I

3.6047.102

Install

1.

NOTE:

you install the cylinder.

Cylinder

Install the cylinder to crankcase gasket. Always use a new gasket. While holding the piston/connecting rod in place, slide the cylinder into the crankcase.

Hold the wrist pin buttons in place as

5-6

2.6047.113

2.6047.115

ENGINE

2.

Install the the cylinder with the the crankcase.

ASSEMBLY

Do

not tighten.

(cont)

two

(2)

screws into

3.

Place

two

(2)

them lightly.

Install

1.

Oil Pan

Install the

Torque the screws to

six

new O-rings on the cylinder. Oil

(6)

screws into the oil pan.

35-45

in-lb

(3.9-5.0

N-m).

ENGINE ASSEMBLY

(cont.)

Cylinder

1

.

NOTE:

when assembling the cylinder head.

2.

Head

Assembly

Make sure you have all assemble the cylinder head, which include

(2)

valves, valve springs and retainers

Always match intake and exhaust parts

Install the valves and valve springs.

of

necessary parts to

1

two

.

I

2.6047.118

3.

Install the sure the retainers lock onto the valve stems properly.

two

(2)

valve spring retainers . Make

5-8

2.6047.119

ENGINE ASSEMBLY

4.

Install a new cylinder head gasket. The notch on the gasket goes to the spark plug side cylinder and the dome side

be

up.

5.

Place the cylinder head over the four

(cont.)

of

the gasket should

(4)

of

the

studs.

6.

Seal the with

7.

Install the push rod guides over the cylinder studs.

RTV

two

(2)

sealing.

cylinder studs in the rocker

box

5-9

ENGINE ASSEMBLY

8.

Install the cylinder head with the four hex nuts and washers.

(cont.)

(4)

cylinder

NOTE: ine Toro hardened

cial dimensions that are critical to the engine's tolerances.

9. NOTE:

the cam followers. Refer to "Cam Bracket Disassembly and Reassembly" in

and

If

the washers need to be replaced, use

washers. These washers have spe-

Install the push rods into the push rod guides.

Make sure the push rods are seated into

Part

4

-

inspection

Repair.

Torque the cylinder head hex nuts to

(3.9-4.5 N-m).

Torque the

(3.9-4.5 N.m).

Torque the nuts in an

two

(2)

cylinder screws to

35-40 in-lb

"X

35-40 in-lb

Genu-

pattern

Install Rocker

1.

Install the rocker arm adjusting nuts, rocker arm pivots and rocker arms.

NOTE:

when assembling the rocker arm assembly.

NOTE:

installing the rocker arm assembly.

5-1

Always match intake and exhaust. parts

Oil the rocker arm adjusting nuts before

0

Arm

Assembly

3.6047.106

Adjusting Nut

Rocker Arm Pivot

Rocker Arm

3.6047.059

lo6

ENGINE

Rocker Arm to Valve Clearance Adjustment

Every

cover and check the rocker arm to valve clearance.

1.

Position the crankshaft top are free and loose).

2.

Measure the clearance between the valve stems and rocker arms,

The recommended rocker arm to valve clearance for

both the intake and exhaust is

mm-.152 mm).

3.

If

as

a. Turn the adjusting nut, using a

ASSEMBLY

50 hours

of

the clearance is not within specification, adjust

follows:

(8

To

clearance,

counterclockwise.

To

clearance, turn the adjusting nut

of

operation, remove the rocker arm

the compression stroke (both rocker arms

using a flat feeler gauge

mm)

wrench or nut driver.

increase the rocker arm to valve

turn the adjusting nut

decrease the rocker arm to valve

(cont.)

so

that the piston is at the

.003-.006 in(.076

5/16

in

clockwise.

.

5

3.6047.058

b. Recheck the clearance with a

gauge

5.

Reinstall the rocker arm cover, using a new

gasket. Torque the rocker arm cover screw to

20-30 in-lb (2.2-3.4 N-m).

I

and readjust as necessary.

flat feeler

5-11

ENGINE

Install Spark Plug

1.

Make sure the spark plug gap is set to

(.0635 mm).

2.

Install the spark plug into the cylinder and torque

to

Install Muffler

1.

Install a new muffler gasket and place the muffler baffle in place.

ASSEMBLY

100-110 in-lb (11.2-12.3 N-m).

(cont.)

0.025 in

3.6047.024

2.

Install the muffler with the three bolts. Install the lower bolt first to ease the installation of the top

NOTE:

next to the spark plug before installing the top rear muf-

fler bolt.

NOTE:

ing bolts.

5-1

The 5 mm nut must be held in the slot

Be careful not to crossthread the muffler mount-

Torque the muffler mounting bolts to

(4.5-5.0

N-m).

2

two

(2)

(3)

bolts.

mounting

40-45

in-lb

2.6047.125

2.6047.040

r

ENGINE

Install Intake Baffle

-

1.

Install the intake baffle on the other side

cylinder.

Install Carburetor Mount Insulator

ASSEMBLY

(cont.)

of

the

1.

Install the

carburetor mount insulator.

For Units with Engine Serial Number

405000001

are retained in the carburetor mount insulator.

2.

Install a new gasket to the back mount insulator. Install the carburetor mount insulator to the crankcase with the screws

Torque the screws to

two

(2)

hex nuts on the back

and Greater-The

.

30-35

two

in-lb

(2)

of

the carburetor

two

(3.3-3.9,

of

the

hex nuts

(2)

N.m).

2.6047126

5-13

ENGINE ASSEMBLY (CONT.)

WARNING: CRACKED

OR

BROKEN COOLING FINS ARE A HAZARD! Be careful not to crack or break any cooling fins. They could fly

during operation.

If

cooling fins are cracked or

off

broken, replace the flywheel.

1.

Install the flywheel key into the keyway on the

crankshaft.

2.

Position the flywheel

so

that the key slot in the flywheel aligns with crankshaft key. Place the fly- wheel onto the crankshaft.

3.

Install the flywheel spacer and clutch rotor to hold

the flywheel in place.

Install Ignition Module

1.

Install the ignition module ground lead tab

terminal and module fastening screws.

J

I27

2.

Move the ignition module away from the flywheel

as far as possible. Tighten the fastening screws

slightly.

3.

Insert a

0.008-0.012 in (0.201-0.305

mm)

feeler gauge or shim stock between the ignition module and the flywheel magnet surfaces.

Loosen the module fastening screws and push the

4.

ignition module tight against the feeler gauge or

shim shock. Torque the screws to Connect the switch lead wires as necessary. Re-

5.

30-40 in-lb (3.3-4.5 N.m).

move the clutch rotor.

2.6047.128

5-1

2.6047.129

4

ENGINE

Install Fan Housing

1.

Install the fan housing with the four

the crankcase.

Torque the fan housing screws to

(4.5-5.0 N.m).

-

Install Fuel Tank And Fuel Tank Bracket-

1.

Install the rubber fuel tank pad to the fuel tank.

ASSEMBLY

(cont.)

(4)

40-45

screws to

in-lb

2.

Install the fuel tank and fuel tank bracket with the

two

(2)

screws.

Torque the screws to

-

Install Starter Module Assembly

1.

Place the starter module over the crankshaft.

2.

Install the starter rope eyelet bracket with the

(2)

screws.

Torque the screws to

25-35 in-lb (2.8-3.3

15-20 in-lb (2.0-2.5

N.m).

two

N-m).

NOTE:

slightly to enable the starter housing to drop into po- sition.

It may be necessary to pull the starter rope

5-1

5

ENGINE ASSEMBLY

(cont.)

Install

1.

Clutch

Install the washer and clutch rotor to the crankshaft. Make sure the spacer is installed on the crankshaft.

3.

Install the isolator onto the starter housing.

5-1 6

ENGINE

ASSEMBLY

(cont.)

4.

Install the clutch cover with the three

If

the unit is equipped with a spring, instal

spring.

35-45

Torque the screws to

Install Primer Bulb, Carburetor And connecty\ Fuel Line

in-lb

(3)

(3.3-5.0

screws.

screws

E

:he

N.m).

t

ci

Gasket (Small)

2.6047.138

Use the following procedure to install the primer

bulb, carburetor and fuel lines into the air filter base.

1.

Install the primer bulb into the air filter base.

2.

Install

two

new carburetor gaskets and the carburetor into the air filter base. The larger gasket goes on the air filter base side and small one on the carburetor to isolator side

the

5-1

7

ENGINE ASSEMBLY

3.

Connect the fuel lines to the carburetor and primer bulb.

(cont.)

2.6047.139

Short Fitting (To Carburetor)

NOTE:

tank. The clear line provides normal fuel flow. The

blue line provides a return line for excess fuel flow during the primer operation. The short fitting on the

fitting goes to the fuel tank.

Install Air Filter Base, Alr Filter and Air Filter Cover

1.

This unit has

bulb comes

Install the Z-bend of the throttle cable into the

third hole from the top in the carburetor throttle

lever.

two

fuel lines to the fuel

from

the carburetor and the long

Long Fitting

(To Tank)

3.6047.140

5-1

2.6047.141

8

INSTALL AIR FILTER BASE, FILTER AND

2.

Install the air filter base, primer bulb and carburetor to the carburetor mount insulator with the three be mounted to the air filter base at the same time.

AIR

FILTER COVER

(3)

screws. The breather hose must

AIR

'

2.6047.031

3.8047.142

Torque the screws to

3.

Install the air filter element onto the air filter

base.

30-35

in-lb

(3.3-3.8

N-m).

3.6051.009

4.

Install the air filter cover with the three screws.

Torque the screws to

25-30

in-lb

(3)

(2.8-3.3

N.m).

5-1

9

ASSEMBLE HANDLE

Install

1.

Lower

Handle

Pull the throttle cable and lead wires through the

housing and place them into the grooves in the

of

bottom

wire in the bottom

the lower handle. Place the switch

of

the slot and then the

throttle cable.

NOTE:

rear

Make sure the wires are placed to the

of

the switch. This will ensure that the switch

the correct on/off position.

is

in

Lead

-

20647.143

2.

Install the spring into the trigger.

5-20

Spring-

ASSEMBLE HANDLE

3.

Assemble the trigger (with the spring), switch and retainer and place the assembly into the bottom

of

the lower handle. The throttle cable must go

through the retainer.

(cont.)

4.

Install the retainer screw, which holds the

and throttle trigger assembly in the lower

Torque the retainer screw to

N.m).

Install

1.

2.

Upper

Install the upper boom into the handle.

NOTE:

sure the spring is installed in the clutch housing/drum assembly before installing the upper boom.

Locate the anti-rotation cap screw and place the

boom onto the cap screw.

Handle

For units that take attachments, make

15-20

in-lb

(

1.

I

;witch handle

Torque the screw

to

15-20

in-lb

(1.7-2.2

N-m).

ASSEMBLE HANDLE

3.

Wrap some masking tape around the boom and the lower handle. This will hold the boom onto the anti-rotation cap screw.

(cont.)

5.

Install the upper handle with the six To aid in the installation of the upper handle, lubricate the isolator with soap and water.

Torque the screws to

Cut the tape and remove it from the lower handle.

6.

20-25

in-lb

(6)

(2.2-2.8

screws.

5-22

L

N-m).

ASSEMBLE

COVERS

3.6047.

Install Engine

1.

Install the engine cover with the four

Cover

Torque the rear engine cover screw to

in-lb

(3.5-4.0

Torque the

in-lb (1.7-2.2 N-m).

Torque the

in-lb (2.5-3.0 N-m).

N-m).

top

engine cover screws to

side

engine cover screw to

(4)

Screws.

30-35

15-20

,

20-25

__

3.6047.036

2.6065.167

Before placing the unit back into service, be sure to do the following:

1.

Make sure all of the fasteners are tightened

securely.

2.

Fill the fuel tank with fresh gasoline and check the oil level in the oil pan. Refer to “Oil and Fuel Recommendations” in

Information.

3.

Adjust the carburetor high speed mixture, idle

Part

7

-

General

speed mixture and idle speed settings. Refer to “Carburetor Adjustment” in

Information.

Part

7 - General

Toro 51921, 51920, 51926, 51927 Service Manual

Specifications and Main Features

Frequently Asked Questions

User Manual