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These carburetors have a fixed high speed main jet with

adjustable idle, Fig 183. 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 Walbro LMT Carburetors

Models 235/245400, 287000, 28N thru W, 310/312/313700

Single Cylinder OHV Engine Repair ManualVersion 1.0

Copyright© 1999 by Briggs and Stratton Corporation

Fig. 183 - Outside View, Carburetor Typical

Remove Carburetor

Remove Air Cleaner

Models 235400, 245400

1. Remove air cleaner knobs and cover.

2. Remove cartridge, pre-cleaner and pre-cleaner filter

retainer.

3. Remove hex. Screw from lower right hand corner of

air cleaner base.

4. Remove two (2) hex. Nuts and fuel spray shield.

5. Remove air cleaner base and air cleaner gasket.

Disconnect breather tube from air cleaner base.

Remove Air Cleaner

Models 287, 28N thru W, 310/312/313700

1. Remove air cleaner cover knob and cover.

2. Remove cartridge knob and cartridge with

pre-cleaner.

3. Push breather tube down out of air cleaner base.

4. Remove upper screw from air cleaner brace and

loosen lower screw.

5. Remove screw from air cleaner base and remove

two (2) nuts holding air cleaner base to carburetor

intake, Fig. 185.

CARBURETION


Remove



Page 1 of 2

Fig. 185 - Remove Air Cleaner

Models 287, 28N thru W, 310/312/313700

Remove Carburetor

Models 235400, 245400

1. Remove knob from throttle control lever.

2. Remove screw holding panel to front control bracket

at carburetor.

3. Remove screw from fuel tank bracket or support

bracket.

4. Remove two hex. screws holding choke control

bracket to governor control bracket, Fig. 186.

5. Slide choke control bracket and carburetor out to end

of carburetor mounting studs. Lift choke control

bracket to clear choke shaft and remove.

6. Remove air cleaner gasket and continue to pull

carburetor off studs until clear of studs.

7. Disconnect link spring from throttle lever and then tip

carburetor over to disengage Z-bend of throttle link

from throttle lever.

Remove Carburetor

Model 287, 28N thru W, 310/312/313700

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. 188.

CARBURETION


Remove



Page 2 of 2

Fig. 186 - Removing Choke Control Bracket

Fig. 188 - Remove Carburetor

Disassemble Carburetor

Models 235/45, 287, 28N thru W, 310/312/313700

1. Remove solenoid and fuel bowl washer.

Note: Models 235400, 245400 do not use

solenoids.

Note: Two (2) styles of solenoids have been used.

Early style had one (1) wire, (RED) connected

to the bottom of the solenoid. The current style

has been made in two (2) versions. However,

both have a two (2) wire connector (GRAY for

solenoid & BLACK, for solenoid ground) on the

side of the solenoid. The early version can only

be removed with an automotive 1/2" tappet

wrench while the late version can be removed

with a regular 1/2" open end wrench.

2. Remove float bowl and float bowl gasket from

carburetor.

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

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

5. Rotate throttle shaft and lever to closed position and

remove two (2) throttle plate screws.

6. Remove throttle plate, throttle shaft with lever, and

foam seal.

7. Remove throttle shaft seal or bushing from carburetor

body.

Choke Shafts

These carburetors are equipped with two styles of

choke shafts:

1. Plastic shaft with snap in choke plate or;

2. Metal shaft with screw mounted choke plate.

Remove Plastic Choke Shaft & Plate

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


Disassemble



Page 1 of 3

Fig. 189 - Solenoid Types

Disassemble Carburetor

Models 235/45, 287, 28N thru W, 310/312/313700

Remove Metal Choke Shaft & Plate

1. Rotate choke shaft and lever to closed position.

Service replacement carburetors may have a spring

detent that will hold choke in closed position.

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.

4. Remove brass pilot jet (with type numbers not ending

in A1 or E1) from carburetor body, Fig. 190.

5. Using Tool #19062, Carburetor Jet Screwdriver,

remove emulsion tube, Fig. 191.

6. With a modified 5/16 inch (3.9 mm) pin punch, remove

welch plug from carburetor body, Fig. 192.

CARBURETION


Disassemble



Page 2 of 3

Fig. 190 - Remove Pilot Jet

Fig. 191 - Remove Emulsion Tube

Fig. 192 - Remove Welch Plug

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. 193.

3. Place 1/4" x 20 nut and washer, 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. 194.

CARBURETION


Disassemble



Page 3 of 3

Fig. 193 - Threading Or Tapping Fuel Inlet Seat

Fig. 194 - Remove Fuel Inlet Seat

Test Solenoid, Current Style

1. Insert jumpers in connector on side of solenoid.

2. Test solenoid by connecting jumpers to a new 9 volt

transistor battery.

3. Plunger needle should snap into solenoid body.

If not, replace.

Test Solenoid, Early Style

1. Test solenoid by connecting jumper from positive post

of a new 9 volt transistor battery to solenoid terminal.

2. Then touch body of solenoid to negative post of

battery. Plunger needle should snap into solenoid

body. If not, replace.

CARBURETION


Test Anti-Afterfire Solenoid



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. 195.

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

seat in until flush with fuel inlet boss, Fig. 196.

Install Metal Choke Shaft

1. Install foam seal and return spring on choke shaft

hooking small hook in notch on choke lever,

Fig. 197, 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. 197.

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.

CARBURETION


Assemble



Page 1 of 4

Fig. 195 - Install Welch Plug

Fig. 196 - Install Fuel Inlet Seat

Fig. 197 - Install Metal Choke Shaft

Install Plastic Choke Shaft

Models 235400, 245400

1. Place foam seal on choke shaft.

2. Install choke shaft and seal in carburetor and turn

shaft clockwise as far as it will go.

3. Install choke plate with number facing towards detent

spring. Rotate choke shaft to center choke plate,

Fig. 198.

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. 199.

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. 199.

CARBURETION


Assemble



Page 2 of 4

Fig. 198 - Install Choke Shaft

Fig. 199 - Install Plastic Choke Shaft

Install Throttle Shaft

Models 235400, 245400

1. Install throttle shaft bushing in carburetor.

2. Slide foam seal onto throttle shaft.

3. Slide throttle shaft and seal into carburetor making

sure idle stop on throttle lever is to left of idle speed

screw.

4. Rotate throttle shaft clockwise until idle stop is

against idle speed screw.

5. Place throttle plate on throttle shaft with numbers

facing into carburetor and to the right.

6. Place a drop of Loctite® on screw threads and

tighten, Fig. 200.

Note: On Model 235400, throttle plate

movement is limited and will not go to the wide

open position. This is normal.

Install Throttle Shaft

Models 287, 28N thru 28W, 310/312/313700

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. 201.

Install Emulsion Tube

1. Install emulsion tube using Tool #19062, Carburetor

Jet Screwdriver, until emulsion tube seats, Fig. 202.

2. After installing emulsion tube, use compressed air to

blow out any chips or debris that may have been

loosened while installing emulsion tube.

Note: On Models 287, 28N thru W, 310/312/313700,

install main jet only after installing emulsion tube.

CARBURETION


Assemble



Page 3 of 4

Fig. 200 - Install Throttle Shaft

Fig. 201 - Install Throttle Shaft

Fig. 202 - Install Emulsion Tube

Install Inlet Needle & Float

1. Insert inlet needle valve 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 45 In. Lbs.

(5 Nm).

Install Idle Screw and Pilot Jet

Install pilot jet (with type numbers not ending in A1 or

E1) until it seats securely. Install idle mixture screw with

spring and turn until head of screw touches spring.

CARBURETION


Assemble



Page 4 of 4

Fig. 202a - Install Inlet Needle - Typical

Install Carburetor

Models 235400, 245400

Install Spacer

Place an intake gasket next to cylinder head, the

carburetor spacer, and a second intake gasket. Both

gaskets have round holes.

1. Hook "Z" bend of governor link into nylon bushing of

throttle lever. Then hook link spring into hole of throttle

lever.

2. Slide carburetor unto carburetor studs until front of

carburetor is flush with end of studs.

3. Place one (1) air cleaner gasket (gasket with two (2)

notches in inside diameter) on carburetor mounting

studs.

4. Install choke control bracket on carburetor making

sure alignment pin on choke shaft is engaged in hole in

control plate, Fig. 203.

5. Place new carburetor mounting gasket on studs and

slide on air cleaner base, fuel spray shield and install

two (2) nuts and one (1) screw to secure air cleaner

base, Fig. 204. Torque nuts and screw to 45 In. Lbs.

(5 Nm).

6. Place fuel spray shield on carburetor studs and install

two (2) hex. nuts. Then install hex. screw in lower

right hand corner of air cleaner base to air cleaner

brace. Torque nuts and screw to 45 In. Lbs. (5 Nm)

7. Assemble pre-cleaner, retainer, and air cleaner

cartridge. Insert tabs on cover in slots of air cleaner

base and close air cleaner cover assembly and

tighten air cleaner knobs, Fig. 205.

8. Install fuel hose and clamp on carburetor inlet.

CARBURETION


Install



Page 1 of 3

Fig. 203 - Install Choke Control Bracket

Fig. 204 - Install Air Cleaner Base

Fig. 205 - Install Air Cleaner Cover Assembly

Install Control Panel

9. Install control panel and torque screw holding bracket

to choke control plate to 45 In. Lbs. (5 Nm). Install

screw holding control panel to fuel tank bracket or

support bracket to 45 In. Lbs. (5 Nm), Fig. 206.

Install Carburetor

Models 287,28N thru W, 310/312/313700

Install Intake Manifold

If carburetor intake was removed, place new gasket

and manifold on intake port and torque screws to

100 In. Lbs. (11 Nm), Fig. 207.

Install Governor Link & 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, Fig 208.

CARBURETION


Install



Page 2 of 3

Fig. 206 - Installing Control Panel

Fig. 207 - Install Intake Manifold

Fig. 208 - Install Governor Link & Spring

Install Choke-a-Matic® Link & 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 90 In. Lbs. (8 Nm), Fig. 209.

3. Install air cleaner body and torque nuts to 60 In. Lbs.

(6 Nm). Install screw inside air cleaner body.

4. Install breather tube in air cleaner body opening.

5. Install air cleaner brace.

CARBURETION


Install



Page 3 of 3

Fig. 209 - Install Carburetor

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