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CARBURETION

Carburetor Identification

IntekTM

Single Cylinder OHV Engine Repair Manual

Version 1.0Copyright© 1999 by Briggs and Stratton Corporation

Models 28S700, 311700Models 110400, 110600, 111400, 111600, 113400, 120400,

120600, 121400, 121600, 122600, 123400, 123600

Models 28S700, 3117002

These carburetors have a fixed high speed main jet with

adjustable idle mixture, Fig. 22. The different carburetors

are identified as LMT 1 and up.

The letters LMT are cast into the body of the carburetor

while the numbers are stamped into carburetor mounting

flange next to idle mixture screw.

CARBURETION

Large B&S/Walbro

Service Carburetor Briggs & Stratton/Walbro LMS

IntekTM



Fig. 22 - Outside View, Carburetor Typical

Remove Carburetor

Models 28S700, 311700

1. Disconnect wire(s) from carburetor solenoid.

2. Remove two (2) carburetor studs while holding

carburetor.

3. Pull carburetor away from governor control bracket

and rotate carburetor to disengage Choke-A-Matic®

linkage, governor link, and governor link spring from

carburetor, Fig. 25.

CARBURETION

Large B&S/Walbro

Remove

IntekTM



Fig. 25 - Remove Carburetor

Disassemble Carburetor

Models 28S700, 311700

1. Remove anti-afterfire solenoid and fuel bowl washer.

2. Remove float bowl and float bowl gasket.

3. Remove float hinge pin, float, and inlet needle.

4. Remove idle mixture needle limiter cap, when used.

5. Remove idle mixture screw with spring and idle

speed screw with spring.

6. Rotate throttle shaft and lever to closed position and

remove two (2) throttle plate screws.

7. Remove throttle plate, throttle shaft, and foam seal.

8. Remove throttle shaft seal or bushing.

Note: These carburetors are equipped with one of

two styles of choke shafts:

a. Plastic shaft with snap in choke plate or;

b. Metal shaft with screw mounted choke plate.

Remove Choke Shaft & Plate (Metal)

1. Rotate choke shaft and lever to closed position.

Note: Service replacement carburetors may have a

spring detent.

2. Hold choke closed and remove two (2) screws

holding choke plate.

3. Remove plate. Release tension on choke shaft and

remove choke shaft and lever, return spring and seal

assembly.

Remove Choke Shaft & Plate (Plastic)

1. Rotate choke shaft to wide open position.

2. Pull choke plate out of choke shaft and lever.

3. Remove choke shaft and lever, return spring (when

used), and foam washer.

CARBURETION

Large B&S/Walbro

Disassemble

IntekTM



Page 1 of 4

Fig. 33 - Remove Metal Choke Shaft

Fig. 34 - Remove Plastic Choke Shaft

Fig. 32 - LMT Exploded View

4. Using Tool #19062, Carburetor Screwdriver, remove

main carburetor emulsion tube, Fig. 27

.Note: Low Emission LMT carburetors have pressed

in pilot jets that are not removable.

DO NOT remove the pressed in style pilot jet,

Fig. 28.

CARBURETION

Large B&S/Walbro

Disassemble

IntekTM



Page 2 of 4

Fig. 27 - Remove Emulsion Tube

Fig. 26 - Pressed-In Pilot Jet Welch Plug

5. With a modified 5/16 inch (4 mm) pin punch, remove

welch plug from carburetor body, Fig. 43.

Remove Fuel Inlet Seat

1. Use self-threading screw Part #93029 from Tool

#19165, Flywheel Puller, or 1/4-20 tap.

2. Thread screw or tap into fuel inlet seat 3-4 turns and

remove, Fig. 44.

CARBURETION

Large B&S/Walbro

Disassemble

IntekTM



Page 3 of 4

Fig. 28 - Remove Welch Plug

Fig. 29 - Threading Or Tapping Into Fuel Inlet Seat

3. Place 1/4" x 20 nut Part #92278 and washer,

Part #224061 from 19332, Tool Kit, onto puller screw.

4. Place a 1/4" drive 3/8" socket over fuel inlet seat.

5. Thread screw into tapped inlet seat until screw

bottoms.

6. Thread nut down unto washer and continue turning

nut until inlet seat is free from carburetor body,

Fig. 45.

CARBURETION

Large B&S/Walbro

Disassemble

IntekTM



Page 4 of 4

Fig. 30 - Remove Fuel Inlet Seat

CARBURETION

Large B&S/Walbro

Carburetor Cleaning Recommendations

IntekTM



Carburetor Cleaning Recommendations

1. Disassemble carburetor.

2. Remove all old gaskets, seals and sealing material.

3. Use commercial carburetor cleaning solvents (such as Briggs & Stratton Spray Cleaner, Part #100041 or #100042) to clean

carburetor parts and body.

4. When cleaning non-metallic parts (plastic, nylon, Minlon, etc.), do not leave in commercial carburetor cleaner bath more than

15 minutes.

Note: Parts containing rubber, such as seals, "O" rings or pump diaphragms should never be placed in commercial

carburetor cleaner bath.

5. Use only compressed air (blowing in both directions) to clean out all openings and passages.

Note: Do not use wires, drills or any other devices to clean out metering holes or passages.

Install Welch Plug

1. Install welch plug with pin punch slightly smaller than

outside diameter of plug. Press in until plug is flat.

DO NOT cave in plug.

2. After plug is installed, seal outside edge of plug with

fingernail polish or non-hardening sealant, Fig. 31.

Install Fuel Inlet Seat

Using Tool #19135, Knockout Pin, press new fuel inlet

seat in until flush with fuel inlet boss, Fig. 32.

CARBURETION

Large B&S/Walbro

Assemble Carburetor

IntekTM



Page 1 of 3

Fig. 31 - Install Welch Plug

Fig. 32 - Install Fuel Inlet Seat

Install Metal Choke Shaft

1. Install foam seal and return spring on choke shaft

hooking small hook in notch on choke lever, Fig. 33,

inset.

2. Insert choke shaft assembly into carburetor body and

engage large end of return spring on boss.

3. If carburetor has spring detent, guide detent spring

into slot on choke shaft lever, Fig. 33.

4. Place choke plate on shaft with single notch on edge

towards fuel inlet. Two (2) half moon dimples will help

to position plate on shaft.

Install Plastic Choke Shaft

1. Insert spring inside large foam seal and slide seal and

spring onto choke shaft with straight end of spring up

toward choke shaft lever.

2. Insert choke shaft into carburetor body until hook of

spring hooks on spring anchor.

3. Lift choke shaft and lever up slightly and turn

counterclockwise until stop on lever clears spring

anchor and push shaft down, Fig. 34.

4. Insert choke plate into choke shaft and lever with

dimples toward fuel inlet side of carburetor. Dimples

help to hold and align choke plate on shaft, Fig. 34.

Install Throttle Shaft

Models 28S700, 311700

1. Install throttle shaft seal with sealing lip down in

carburetor body until top of seal is flush with top of

carburetor.

2. Install throttle shaft and small foam washer.

Turn shaft until flat is facing out.

3. Lay throttle plate on shaft with numbers toward idle

mixture screw and dimples facing in resting on edge

of shaft. Install two (2) screws, Fig. 35.

CARBURETION

Large B&S/Walbro

Assemble Carburetor

IntekTM



Page 2 of 3

Fig. 33 - Install Metal Choke Shaft

Fig. 34 - Install Plastic Choke Shaft

Fig. 35 - Install Throttle Shaft

Install Inlet Needle & Float

1. Insert inlet needle in slot on float.

2. Place float and needle on carburetor and install float

hinge pin centering hinge pin.

3. Place bowl gasket on carburetor body.

4. Place bowl on carburetor and install solenoid and

float bowl washer torquing solenoid to 40 in. Lbs.

(5 Nm).

Install Idle Mixture Screw

Install idle mixture screw with spring and turn until head

of screw touches spring.

Install Emulsion Tube

1. Install emulsion tube using Tool #19062, Carburetor

Screwdriver, until tube seats, Fig. 51.

2. After installing emulsion tube, use compressed air to

blow out any chips or debris that may have been

loosened while installing tube.

Note: On Models 28S700, 311700, install main jet

after installing emulsion tube.

CARBURETION

Large B&S/Walbro

Assemble Carburetor

IntekTM



Page 3 of 3

Fig. 36 - Install Emulsion Tube

Fig. 35 - Install Inlet Needle & Float

Install Intake Manifold

If carburetor elbow was removed, place new gasket

and manifold on intake port and torque screws to 100 in.

Lbs. (11 Nm).

Install Governor Link and Spring

1. Place two (2) studs on carburetor and new gasket on

studs with long edge on side of gasket opposite fuel

inlet.

2. Hook governor link spring in throttle lever hole without

grommet.

3. Hook governor link in throttle lever hole grommet with

link on top of lever.

Install Choke-A-Matic® Link and Carburetor

1. Insert "U" bend of Choke-A-Matic® link in outer hole of

choke lever from bottom of lever.

2. Slide "U" bend of link into slot on governor control

bracket and place carburetor on intake elbow.

Torque studs to 65 in. Lbs. (7 Nm), Fig. 37.

3. Install air cleaner body and torque nuts to 55 in. Lbs.

(6 Nm). Then install screw inside air cleaner body.

4. Install breather tube in air cleaner body opening.

5. Install air cleaner brace.

CARBURETION

Large B&S/Walbro

Install Carburetor - Models 28S700, 311700

IntekTM



Fig. 37 - Install Carburetor

Fig. 36 - Install Carburetor

Adjust Carburetor

1. Start and run engine for 5 minutes at 1/2 throttle to

bring engine up to operating temperature.

2. Move equipment control to idle position.

3. Turn idle speed screw to obtain 1750 RPM Minimum.

4. Turn idle mixture screw slowly clockwise until engine

just begins to slow.

5. Then turn screw opposite direction until engine just

begins to slow. Turn screw back to midpoint.

6. Install limiter cap with flat facing up, (when so

equipped) Fig. 38.

Note: If engine is adjusted for governed idle, reset idle

speed screw to 1200 RPM. For governed idle

adjustment procedure see Section 5.

7. Move equipment speed control from idle to high speed

position. Engine should accelerate smoothly. If it does

not, open idle mixture needle screw 1/8 turn open.

There should be no afterfire.

CARBURETION

Large B&S/Walbro

Adjust Carburetor

IntekTM



Fig. 38 - Install Limiter Cap

Test Solenoid, Current Style

Models 28S700, 311700

1. Insert jumpers in connector on side of solenoid.

2. Test solenoid by connecting jumper wires to a new

9 volt transistor battery.

3. Plunger needle should snap into solenoid body.

If not, replace.

Test Solenoid, Early Style

Models 28S700, 311700

1. Test solenoid by connecting jumper wire from positive

post of a new 9 volt transistor battery to solenoid

terminal.

2. Touch body of solenoid to negative post of battery.

Plunger needle should snap into solenoid body. If not,

replace.

CARBURETION

Large B&S/Walbro

Anti-Afterfire Solenoid

IntekTM



Fig. 24 - Solenoid Types

Anti-Afterfire Solenoid

Afterfire can be caused by broken wires, poor grounds, defective solenoid or wiring of the ignition switch.

Afterfire can be caused by using the anti-afterfire terminal of the five (5) terminal key switch to also turn off the alternator

when the engine is shut off. When the key is turned to the off position, as long as the engine continues to slow down, the

alternator is putting out voltage and current. This current will flow through the anti-after fire solenoid allowing fuel to go

through the engine into the hot muffler causing after fire. If the equipment is wired this way, replace the five (5) terminal

switch with a six (6) terminal switch using the correct diagram for the type of alternator used, as shown in MS-0415.

Note: Two (2) styles of solenoids have been used, Fig. 24. Early style had one (1) wire, (RED) connected to the bottom of

the solenoid. The current style has a two (2) wire connector (GRAY for solenoid & BLACK, for ground) on the side of the

solenoid. Some versions can only be removed using an automotive 1/2" tappet wrench

Fig. 25 - Solenoid Test

carburetion - justanswerww2.justanswer.com/uploads/mr2cycle/2011-03-21_024409_280000... ·...

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