Toro 51643, 51644, 51645 Service Manual

TC3, 4, 5000 GAS TRIMMER, MODELS 51643, 51644, 51645

Table of Contents – Page 1 of 4

ABOUT THIS MANUAL

SAFETY INFORMATION

FOR YOUR SAFETY...

SPECIFICATION

TOOL REQUIREMENTS:

TROUBLESHOOTING

MAINTENANCE MAINTENANCE - AIR CLEANER MAINTENANCE - MUFFLER MAINTENANCE - SPARK PLUG MAINTENANCE - FUEL FILTER MAINTENANCE - COOLING SYSTEM MAINTENANCE - TRIMMER IMPLEMENT MAINTENANCE - PREPARATION FOR STORAGE MAINTENANCE - GEARBOX LUBRICATION

SECTION 1 CARBURETOR CARBURETOR OPERATION CARBURETOR OPERATION - THE DIAPHRAGM PUMP CARBURETOR OPERATION - FUEL METERING & MIXING CARBURETOR OPERATION - THE PRIMER SYSTEM CARBURETOR - REMOVAL CARBURETOR - DISASSEMBLY CARBURETOR - REASSEMBLY CARBURETOR - INSTALLATION CARBURETOR ADJUSTMENT - IDLE SPEED CARBURETOR ADJUSTMENT - MIXTURE CARBURETOR ADJUSTMENT - THROTTLE VALVE

SECTION 2 FUEL SYSTEM FUEL TANK - FUEL TANK - REMOVAL FUEL TANK - INSTALLATION PRIMER PUMP - PRIMER PUMP - PROPER USE PRIMER PUMP - OPERATION PRIMER PUMP - DISASSEMBLY PRIMER PUMP - INSPECTION PRIMER PUMP - REASSEMBLY FUEL PICKUP TUBE AND FILTER - SERVICE FUEL CAP - FUEL CAP - OPERATION

TC3, 4, 5000 GAS TRIMMER, MODELS 51643, 51644, 51645

Table of Contents – Page 2 of 4

SECTION 2 FUEL SYSTEM - Continued FUEL CAP - DISASSEMBLY FUEL CAP - INSPECTION FUEL CAP - REASSEMBLY

SECTION 3 IGNITION IGNITION OPERATION IGNITION OPERATION - FLYWHEEL IGNITION OPERATION - IGNITION COIL IGNITION OPERATION - TRIGGER MODULE IGNITION OPERATION - SPARK PLUG AIR GAP ADJUSTMENT TC3000/TC4000 AIR GAP ADJUSTMENT - PREPARATION TC3000/TC4000 AIR GAP ADJUSTMENT TC3000/TC4000 AIR GAP ADJUSTMENT - REASSEMBLY TC5000 AIR GAP ADJUSTMENT - PREPARATION TC5000 AIR GAP ADJUSTM ENT TC5000 AIR GAP ADJUSTMENT - REASSEMBLY COIL - COIL - REMOVAL COIL - INSTALLATION

SECTION 4 RECOIL STARTER RECOIL STARTER - OPERATION RECOIL MECHANISM - REMOVAL RECOIL MECHANISM - DISASSEMBLY RECOIL MECHANISM - REASSEMBLY RECOIL MECHANISM - INSTALLATION STARTER PULLEY - REMOVAL STARTER PULLEY - INSTALLATION

SECTION 5 CLUTCH SHOES AND FLYWHEEL CLUTCH SHOES AND FLYWHEEL - OPERATION CLUTCH SHOES AND FLYWHEEL - DISASSEMBLY CLUTCH SHOES AND FLYWHEEL - INSPECTION CLUTCH SHOES AND FLYWHEEL - REMOVAL CLUTCH SHOES AND FLYWHEEL - REASSEMBLY CLUTCH DRUM AND CLUTCH HOUSING - CLUTCH DRUM AND CLUTCH HOUSING - CLUTCH DRUM AND CLUTCH HOUSING - REASSEMBLY ISOLATION MOUNT (TC4000 AND TC5000 ONLY) - ISOLATION MOUNT - ISOLATION MOUNT - DISASSEMBLY ISOLATION MOUNT - REASSEMBLY

SECTION 6 ENGINE ENGINE - OPERATION ENGINE - REMOVAL FROM DRIVE TUBE

TC3, 4, 5000 GAS TRIMMER, MODELS 51643, 51644, 51645

Table of Contents – Page 3 of 4

SECTION 6 ENGINE - Continued ENGINE - DISASSEMBLY ENGINE - CLEANING AFTER DISASSEMBLY ENGINE - INSPECTION ENGINE - REASSEMBLY ENGINE - INSTALLATION ON DRIVE TUBE

SECTION 7 CONTROLS

CONTROL - DISASSEMBLY CONTROL - REASSEMBLY GRIP - REMOVAL GRIP - INSTALLATION

SECTION 8 HANDLE TC3000 HANDLE - REMOVAL FROM DRIVE TUBE TC3000 HANDLE - INSTALLATION ON DRIVE TUBE TC3000 HANDLE - ADJUSTMENT TC4000 HANDLE - REMOVAL FROM TUBE TC4000 HANDLE - INSTALLATION ON DRIVE TUBE TC4000 HANDLE - ADJUSTMENT TC5000 HANDLE - REMOVAL FROM DRIVE TUBE. TC5000 HANDLE - INSTALLATION ON DRIVE TUBE TC5000 HANDLE - ADJUSTMENT

SECTION 9 SHIELD

SHIELD - REMOVAL FROM DRIVE TUBE SHIELD - INSTALLATION ON DRIVE TUBE SHIELD - MOUNTING CUTTER KNIFE ON SHIELD

SECTION 10 GEARBOX

GEARBOX - REMOVAL GEARBOX - INSTALLATION ON DRIVE TUBE GEARBOX - SEAL REMOVAL GEARBOX - SEAL INSTALLATION

SECTION 11 DRIVE SHAFT AND TUBE

DRIVE SHAFT - DRIVE SHAFT - REMOVAL DRIVE SHAFT - INSTALLATION DRIVE TUBE - DRIVE TUBE - REMOVAL DRIVE TUBE - INSTALLATION

SECTION 12 LEECO MANUAL FEED HEAD

LEECO MANUAL FEED HEAD - SPOOL REMOVAL LEECO MANUAL FEED HEAD - LINE REPLACEMENT LEECO MANUAL FEED HEAD - SPOOL INSTALLATION

TC3, 4, 5000 GAS TRIMMER, MODELS 51643, 51644, 51645

Table of Contents – Page 4 of 4

SECTION 12 LEECO MANUAL FEED HEAD - Continued LEECO MANUAL FEED HEAD - DISASSEMBLY LEECO MANUAL FEED HEAD - INSPECTION LEECO MANUAL FEED HEAD - REASSEMBLY

SECTION 13 KAAZ MANUAL FEED HEAD

KAAZ MANUAL FEED HEAD - DISASSEMBLY KAAZ MANUAL FEED HEAD - LINE REPLACEMENT KAAZ MANUAL FEED HEAD - REASSEMBLY

SECTION 14 PLASTIC FIXED LINE HEAD

PLASTIC FIXED LINE HEAD - LINE REPLACEMENT PLASTIC FIXED LINE HEAD - REMOVAL

SECTION 15 METAL FIXED LINE HEAD

METAL FIXED LINE HEAD - LINE REPLACEMENT METAL FIXED LINE HEAD - REMOVAL METAL FIXED LINE HEAD - INSTALLATION

SECTION 16 TAP AND TRIM HEAD

TAP AND TRIM LINE REPLACEMENT - TAP AND TRIM SPOOL - TAP AND TRIM SPOOL - LINE REPLACEMENT TAP AND TRIM SPOOL - INSTALLATION TAP AND TRIM HEAD - DISASSEMBLY TAP AND TRIM HEAD - INSPECTION TAP AND TRIM HEAD - REASSEMBLY

SECTION 17 METAL BLADES

METAL BLADE - REMOVAL METAL BLADE - INSTALLATION

SECTION 18 HARNESSES STANDARD AND DELUXE HARNESS - ASSEMBLY

SECTION 19 SPARK ARREST O R MUFFL ER

SPARK ARRESTOR MUFFLER - REMOVAL SPARK ARRESTOR MUFFLER - INSTALLATION SPARK ARRESTOR MUFFLER - MAINTENANCE

ABOUT

This Service Manual was written expressly for the Tor0 TC3000, TC4000 and TC5000 Gas Powered Trimmers. The Tor0 Company had made every effort to

make the information

in

this manual complete and correct.

THIS

MANUAL

This manual was written with the service technician that information used most often is

information on safety, maintenance, specifications, special tools and

troubleshooting all

Disassembly, inspection and reassembly procedures are covered two-thirds of the manual and are grouped by component. We tried to cover each common repair with its own section or sub-section. For example, you will find that air gap adjustment and ignition coil replacement are called out separately.

And, because certain components are often difficult to troubleshoot without a

good

understanding of how they work, we have included some component theory. This information can be found of the beginning of most service procedure sections.

We are hopeful that you will find this manual a valuable addition to your shop. If you should come across any errors or if you have any questions regarding this manual, please contact us at the following address:

in

the front third of

81

11

Bloomington, MN, USA 55420

up

front. As a result, you will find reference

the

manual.

The Tor0 Company

Lyndale Avenue South

in

mind.

It

is organized

in

so

the last

The Tor0 Company reserves the right to change product specifications or this manual without notice.

The Tor0 Company gratefully acknowledges the assistance of Mitsubishi Heavy Industries, Ltd.

in

the production of this manual.

(C)

The Toro Company

MINNEAPOLIS,

MN

1987

55420 -USA

Reference Information

Safety Information Specifications 2

Tool Requirements

TABLE OF CONTENTS

Page

1

5

Service Procedures

Section

Section 2 Fuel System

1

Troubleshooting Maintenance

Carburetor Page

operation 11 removal

disassembly 14

reassembly 16 installation 18 adjustment 18

Fuel Tank

removal 20 installation 20

6

8

14

Primer Pump

properuse 21 operation

disassembly 22 inspection 22

reassembly 22

Fuel Pickup Tube and Filter

service 23

Fuel Cap

operation 23 disassembly 24 inspection 24 reassembly 24

21

Service Procedures (cont'd)

TABLE

OF

CONTENTS

Page

Section

5

operation airgapadjustment coilremoval coil installation

Recoil Starter Recoil Mechanism

operation removal disassembly reassembly

installation

Starter Pulley

removal installation

Clutch and lsomount Clutch Shoes and Flywheel

operation disassembly

inspection

25 27 28 29

30 30 30 31

32

33 33

34 34

34

Section

6

removal reassembly

Clutch Drum and Housing

disassembly reassembly

lsomount

Engine

(TC4000

operation

disassembly reassembly

operation removal

disassembly cleaning after disassembly inspection

and TC5000 only)

from

drive tube

35 35

36 37

37

38

40

41 42

43

Service Procedures (cont’d)

Section 6 Engine (cont’d)) Page

TABLE

OF

CONTENTS

Section

8

7

reassembly installation on drive tube.

Control and Grip Control

disassembly 46

reassembly

Grip

removal installation

Handle

TC3000

removal from drive tube 48 Installation on drive tube. 48

adjustment

TC4000

removal from drive tube installation on drive tube. adjustment.

44

45

48 48 49

Section

9

10

TC5000

removal from drive tube installation on drive tube.

adjustment.

Shield

removal from drive tube installation on drive tube. mounting cutter knife on shield

Gearbox

removal from drive tube

installation on drive tube. sealremoval sealinstallation

49

50

52

53

54 54

Service Procedures (cont’d)

Drive Shaft

Drive

TABLE

removal 56 installation 56

Tube

removal 56 installation 57

OF

CONTENTS

Section

Section 14 Plastic Fixed Line Head

12

13

Leeco@ Manual Line Feed Head

sped

removal 58 linereplacement 58

installation 58

Head

disassembly 59 inspection 59 reassembly 59

Kaaz@ Manual Line Feed Head

head disassembly 61 linereplacement 61 headreassembly 62

linereplacement headremoval 63 headinstallation 64

63

Section 15 Metal Fixed Line Head

linereplacement headremoval headinstallation

Section 16 Tap and Trim@ Head

Spool

removal 67 linereplacement 67 installation 67

65

66

Service Procedures (cont’d)

TABLE

OF

CONTENTS

Section

Section 17

Section 18

Section 19

Tap and Trim@ Head (cont’d)

Head

disassembly 68 inspection 68

reassembly 68

Metal Blades

removal 69 installation 69

Harnesses

assembly

Spark Arrestor Muffler

removal 71 installation 71 maintenance 71

Page 16

70

SAFETY INFORMATION

This manual is intended

this safety symbol manual only. The safety instructions provided

means WARNING CAUTION product only. The individual Operator’s Manual will

A

INSTRUCTION Read the instruction TC3000. because Failure to comply with the instruction may result

PERSONAL SAFETY contain safety information on the operation of the

it

has to do

in

personal injury

with

or

FOR

or

safety.

death.

YOUR SAFE

manual are for the troubleshooting and service of the

Operator’s Manuals with complete operational safety instructions are available through:

as

TC4000.

Minneapolis,

or TC5000.

The Tor0 Company

Publications Department

81

11

Lyndale Avenue South

MN

TY...

a service and repair

55430

U.S.A.

in

this

I----

Avoid possible explosions Avoid unexpected starting of the engine Store fuel in a container designed for gasoline and Always disconnect the spark plug wire before never smoke while working around gasoline. attempting any cleaning, adjustment or repair.

Avoid fires Avoid contact with a moving cutter head Never allow the trimmer engine closer than one meter Always stay clear of the cutter head when the engine (three feet) to any combustible material. is running. The clutch is a mechanical device which

Avoid accidental misuse of fuel Always store fuel in an approved container that is properly labeled.

Avoid falls Always wipe up spilled fuel or oil.

Avoid asphyxiation Never operate an engine proper ventilation.

in

a confined area without

could fail. Do not rely on

from turning. Avoid blindness

Always wear eye protection when repairing or running a gas trimmer.

Avoid hearing

Wear ear protection when running a gas trimmer.

loss

it

to keep the cutter head

1

Engine Specifications

SPECIFICATIONS

TC3000

and

TC4000

Service Specifications

2

SPECIFICATIONS

(cont'd)

TC3000 and TC4000 Service Specifications (Cont'd)

Piston Ring

Side

Clearance

0.020

(0.0008

TC5000 Service Specifications

to

0.060

0.0024")

mm

0.150

mm

.

(0.0059")

3

SPECIFICATIONS

Carburetor Specifications

Item Standard

Throttle Valve Needle Jet

1.4

to 1.6mm

(0.055

(cont'd)

to

0.W')

Idle Speed Adjusting Screw Adjust

Fastener Torques

Fastener

Crankcase Screws

(2500

kgm

0.4

to

so

0.5

idle

200

is

rpm

(3000

on

200

TCSOOO)

rpm on TC3000 and

in

Ibs

35 to 43

TC4000

TOOL

REQUIREMENTS:

Flywheel Puller Tor0 part number 41-7650 Dial Indicator

V

Spark Tester Tor0 part number41-7890

Tachometer

Feeler Gauge

Compression Gauge Metric Socket Set Spark Plug Socket #2 Phillips Screwdriver

12

oz.

Ball Peen Hammer

3/8”

Tor0

Drive

part number 42-2730

Magnetic Spark Plug Gapping Torque Wrench Threebond #1104 Tor0 part number

Loctite #242 Tor0 part number Micrometer Snap Ring Plier (inside Hex. Key Set

Blocks & Dial Indicator Stand

Tool

&

outside type)

505-80

505-76

5

TROUBLESHOOTING

Engine Does Not Produce Spark

Engine

Floods

During Starting

Engine Not Getting Fuel

crankcase

leak

TROUBLESHOOTING

Engine Lacks Power

Engine Has Low Compression

(cont’d)

Remedy

Engine Backfires (indicated by burnt air cleaner element)

Trimmer Vibrates Excessively

I

7

Maintenance

Air

Cleaner

Servicing of the air cleaner is recommended after every

25

hours of operation or more often in very dusty

conditions.

See

Figure

1.

Maintenance Muffler Decarbonizing the muffler is recommended after every

50

hours of operation or

drastically. See Figure

if

engine speed decreases

2.

AIR

1.

Remove the

FILTER

FILTER SCREEN

Figure

two

screws securing the air cleaner

1

GRID

FOAM FILTER

cover to the trimmer

Carefully remove the filter grid, foam filter and filter

2.

screen.

Figure

1.

Remove the three screws securing the muffler

2

cover to the trimmer.

2.

Remove the

two

nuts securing the muffler to the

engine.

3.

Rotate the engine crankshaft until the piston totally covers the exhaust port. Clean the exhaust port

area by using a clean flat piece of hard wood.

Remove all loose particles.

Wash the foam filter in a soap and water solution

3.

and dry thoroughly. damage replace

4.

Saturate the foam filter with 5ml (one teaspoon) of

SAE

30

oil, then squeeze to distribute the oil evenly

If

the filter shows any sign of

it.

and to remove excess oil. The element should be damp but not wet.

Wash the filter screen in a clean solvent and air dry.

5.

If

the filter screen shows any signs of damage,

replace Reinstall the air cleaner components as shown in

6.

Figure

it.

1.

Note that the flat side of the filter grid

faces the foam filter. Tighten the air cleaner screws to

7.

(13

to

17.5

in Ibs)

0.15

to

0.20

kg m

8

IMPORTANT

the exhaust port. Stay clear

will

not be damaged.

4.

Inspect the inside of the muffler for excessive carbon buildup.

Use extreme care

If

carbon buildup appears to be

when

of

the piston

cleaning

restricting the exhaust flow, replace the muffler. Otherwise, clean the muffler by holding

it

vice grips and heating with a propane torch. Once

hot, break the carbon loose by hitting the muffler on

a

hard surface. Ensure that the muffler is

completely free

of

all carbon particles before

reinstalling.

5.

Reinstall muffler using a new muffler gasket and tighten all fasteners securely.

6.

Reinstall

the

muffler cover as shown in Figure

so

with a

1.

it

Maintenance Spark Plug

The TC3000, BMGA spark plug or the equivalent. Correct gap is mm

(0.024-0.028”).

for the spark plug is

1.

Stop the engine and pull

2.

Clean around the spark plug and remove the spark plug from

IMPORTANT: Replace spark plug.

TC4000

and the TC5000 each use an

The recommended servicing interval

25

hours of operation.

off

the spark plug wire.

the

engine using a 19mm

a

cracked, fouled or dirty

Do

not sand blast, scrape or clean

(3/4")

NGK

0.6-0.7

socket.

electrodes because engine damage could result

from

grit entering the cylinder.

3.

Set the plug gap to 0.6-0.7mm Figure

3.

I3

(.024-.028”)

.024

(0.6

0.7

See

.028"

mm)

5.

Push the pickup assembly back into the tank and install the gas cap.

Figure

4

Maintenance Cooling System Before each use, visually inspect the cooling air inlet, the

cooling fins, and the openings around the muffler for

debris. Obstruction of these areas could lead

to

overheating and possible engine damage.

Figure

Reinstall the plug and gasket in the engine. Tighten

4.

to

1.2

kg m

(1

04

in Ibs)

3

Maintenance Fuel Filter Fuel filter replacement is recommended after every

hours of operation.

1. Drain the fuel from the fuel tank into a container designed for gasoline. Start the engine and run at idle speed until

it

stops and all fuel is

expended.

2.

Remove the fuel tank cap. Insert a clean wire with

a

hooked end into the tank and hook the pickup tube above the filter. Pull the filter and hose fuel tank opening. See Figure

3.

Remove the filter by holding the black tubing and

pulling the filter straight

4.

Replace the filter assembly.

4.

off.

out

let

the

25

to

Be careful not

damage the cooling fins during

cleaning.

Maintenance Trimmer Implement

The trimmer implements require no lubrication. However, cleaning of the implement and the drive shaft area is recommended after every More frequent cleaning may be required very tall grass or

if

the implement area gets excessively

25

hours of operation.

if

trimming in

hot.

to

the

Refer

Table

of

Contents for the location of information on removal and cleaning of your particular implement.

Maintenance Preparation

for

Storage

The following procedure is recommended to ensure proper operation of the trimmer before storage of more than a month.

it

1.

Drain

the

fuel from the tank into a container designed for gasoline. Start the engine and run at idle speed until

it

stops and all fuel

let

it

is

expended.

2.

Remove dirt and grime from external parts of the

trimmer. Ensure that the cooling fins are clean.

3.

Pull

the spark plug wire off the spark plug. Clean

so

around the plug

that debris will not fall into the sparkplug hole when the plug is removed. Remove the spark plug.

9

Maintenance Preparation for Storage (cont’d)

4.

Pour 5ml (one teaspoon) of two-cycle oil into the spark plug hole This will prevent corrosion from

damaging internal engine components.

5. Pull the recoil starter handle several times to distribute the oil throughout the engine.

6.

Reinstall in Ibs).

the

spark plug. Tighten

DO

NOT CONNECT

it

PLUG

to

WIRE

1.2

kg m

TO

(104

THE

SPARK PLUG.

Maintenance Gearbox Lubrication Lubrication of

after every

1.

Remove the cutter implement from the trimmer. Refer to the Table

the

cutter head gearbox is recommended

40

hours of operation.

of

Contents for the location of information on removal of your particular implement.

2.

Remove the gear case cap and the spacer sleeve

from the drive shaft. See Figure

5.

3.

Clean any debris from under the gear case cap.

4.

Clean the grease fitting, then fill a general purpose number

the

2

lithium base grease until grease is forced out from around the drive Shaft.

5. Reinstall the spacer sleeve and

the

on the drive shaft.

6.

Reinstall the trimmer implement See the Table Contents for the location of information on installation of your particular implement.

gear case with

gear case cap

of

Figure

5

10

SECTION

Carburetor Operation

The carburetor used on the TC3000, TC4000 and the TC5000 is a diaphragm style carburetor. alternating pulses from the crankcase to pump fuel from the fuel tank to the carburetor.

It

1

uses

CARBURETOR

n

To adequately describe the function

is necessary to break its operation down into three

systems:

The Diaphragm Pump

Fuel Metering and Mixing System

The Primer System

Carburetor Operation The Diaphragm Pump

The diaphragm pump requires alternating positive and

negative air pressures working upon

fluctuate and perform a pumping function. The source of

the positive and negative pressures is the lower

crankcase where these pressures are alternately being created by the up and down movement of the piston.

Transfer of these pressure pulses is accomplished by a

passage which leads from the lower crankcase to a point

just below the intake port. See Figure

of

the carburetor,

it

in order to

6.

it

PULSE PASSAGE

The pulses vary with the movement of the piston.

piston moves upward, vacuum is created which pulls the diaphragm toward the pulse hole. This movement results

in

three things happening on the pump cover side of the

diaphragm. See Figure

Figure

8.

PULSE

7

HOLE

As

the

PULSE

PASSAGE

Figure

From there, the passage leads through the intake flange and into the carburetor. It terminates in the diaphragm chamber at a point called the pulse hole. See Figure

6

7.

FUEL

PUMP

COVER

FUEL

INLET

CAVITY

Figure

8

1.

The oulet flapper valve cover. This seals the outlet passage to ensure that fuel is drawn only through the fuel inlet.

is

drawn toward the pump

11

Carburetor Operation

The

Diaphragm Pump

(cont’d)

2.

The inlet flapper valve is pulled open to allow fuel

to flow from the fuel line and into the fuel inlet cavity.

3.

Fuel is drawn into the fuel pump cavity.

As

the piston moves downward, another sequence

occurs which pumps the fuel from the pump cavity

into

the

the main diaphragm cavity. See Figure

9.

FUEL PUMP CAVITY

INLET

NEEDLE

Figure

1.

The exhaust stroke sends a positive pressure pulse

9

to the pump diaphragm which pushes the

diaphragm toward the pump cover.

2.

The positive pressure in the fuel pump cavity seals the inlet flapper valve to prevent fuel from being forced back into the fuel line.

3.

The outlet flapper valve is pushed open.

4.

Fuel is forced out of

the

pump cavity and past the

inlet needle.

I

MAIN

DIAPHRAGM

CAVITY INLET

Figure

10

NEEDLE

Carburetor Operation Fuel Metering Mixing

With the main diaphragm filled with fuel, the carburetor

meters the amount going into the engine by using the high speed mixture screw and the needle entering the intake port

with air to further atomize

of

the engine, the fuel is mixed

it

and increase its

jet.

Before

combustibility. The metering and mixing operation is described below:

See Figure

11.

n

THROTTLE VALVE

SECONDARY NEEDLE JET

NOTE:

The inlet needle is spring loaded in the

closed position. The spring pressure is very slight and is easily overcome by the force of the fuel coming through the passage.

5.

The fuel enters the main diaphragm cavity. Figure

NOTE:

reservoir

10.

The main diaphragm serves only as a

so

that fuel can be properly metered before entering the venturi. It does not do any pumping of fuel during normal operation.

6.

Once the positive pressure is gone, the needle

valve is reseated. This allows fuel to

be

drawn from the sealed main diaphragm cavity and into the carburetor throat on the intake stroke.

See

12

HIGH SPEED MIXTURE screw

CAVITY

Figure

1.

On the intake stroke, vacuum in the carburetor

11

throat draws fuel from the main diaphragm cavity. Note that as the intake stroke begins, the main diaphragm cavity is filled with fuel and that the diaphragm is bowed toward the cover.

Carburetor Operation Fuel Metering & Mixing (cont’d)

2.

The fuel is drawn through the hole in the top of the

main diaphragm chamber and past the high speed mixture screw. The high speed mixture screw

regulates the maximum amount of fuel

that

enter the carburetor throat.

3. The fuel is then drawn past the secondary needle which is attached to the throttlevalve.

It

moves with the throttle valve and regulates the amount of fuel allowed into the carburetor throat in proportion with the throttle setting.

4. The

venturi

is the portion of a carburetor throat that

is narrowed in order to increase air velocity. On the

TC1000 carburetor, the venturi size is variable and

is controlled by the postion See Figure

12.

of

the throttle valve.

can

6.

To better atomize the fuel, an air correction

jet

was added. The air correction jet allows filtered air to enter the carburetor throat perpendicular to the

normal air flow. This action creates turbulence in

the

venturi area and helps mix the fuel with air as

it

enters the carburetor throat.

7.

The air/fuel mixture enters the engine.

See

Figure 13.

Carburetor Operation The Primer System The TC3000, TC4000 and TC5000 trimmers use a primer

system that ensures fuel is present throughout the fuel system. When properly used, this primer system should not induce flooding.

The recommended procedure for priming is as follows: See Figure

14

THROTTLE

VALVE

Figure 12

5.

The vacuum in the venturi area draws the fuel past the secondary needle jet and into the carburetor throat.

VENTURI

CHOKE

OVERFLOW

LEVER

TUBE

\

Figure 14

Push the tickler button fully inward.

Manually pump the primer pump until a small amount of fuel is emitted from the overflow tube. Stop pumping the primer pump and release the tickler valve. The engine is now ready to start.

AIR

CORRECTION

Figure 13

JET

The operation

Figure 15.

1.

2.

13

of

the primer system is as follows:

When the tickler valve is depressed slightly, the inlet needle is unseated.

Depressing the tickler valve fully keeps the inlet needle unseated and also opens the overflow needle.

See

Carburetor Operation The Primer System (cont’d)

2.

Pull from the carburetor the overflow line and the fuel feed line. Remove the carburetor with attached throttle wire. Next, remove

the

two

screws with lock washers, that secure the carburetor onto the intake flange. See Figure

17.

MAIN

DIAPHRAGM

CAVITY

OVERFLOW

3.

Pumping the primer pump forces fuel into the

NEEDLE

Figure

TICKLER

15

BUTTON

entire fuel system. This action ensures that the fuel line, diaphragm pump, and main diaphragm cavity are all filled with fuel.

NOTE: If the tickler valve is not fully depressed during priming, the overflow valve will not open and fuel will be forced into the carburetor throat thereby flooding the engine.

4.

Releasing the tickler valve seats the overflow valve and the inlet needle. At this point the engine is ready for starting.

Carburetor Removal

1.

Remove the

two

screws with flat washers and lock washers, securing the air cleaner assembly and remove the assembly. See Figure

16.

Figure

3.

Remove the intake flange, gasket and insulators.

4.

Remove the

assembly

two

to

the cylinder and carefully remove the

17

screws securing the intake

intake flange, insulator gasket, insulator and plate. IMPORTANT: Before removing the intake

flange, note the position of the pulse orifice through the flange: this orifice should be positioned toward the fuel tank as corresponding orifice

in

the carburetor. The

it

matches a

intake flange can be incorrectly positioned. This will result

NOTE:

The screws securing the intake flange may

in

fuel starvation.

have become heat seized and difficult to remove.

They can be loosened by firmly tapping the

screwdriver into the screws. During reassembly, a sparse application of anti-seize compound to

these threads can prevent future heat seizure.

Carburetor Disassembly

1.

Separate the carburetor from the throttle by unscrewing the mixing chamber cap and removing the throttle cable and the attached throttle valve, needle jet, throttle spring and spring retainer. See Figure

18.

Figure

16

14

Figure

18