Y

1. Screw

2. Choke back spring

3. Choke lever

4. Choke shaft sub-assy

5. Choke valve relief spring

6. Choke valve set screw

7. Choke valve

8. Air horn

9. Main passage plug

10. Strainer

11. Strainer cap

12. Inlet strainer gasket

13. Fttting

14. Screw

15. Spring washer

16. Air horn gasket

17. Float & needle sub-assy

18. Needle valve sub-assy

19. Needle valve seat gasket

20. Float lever pin

21. Float sub-assy

22. Pump spring retainer

23. Pump spring

24. Step up rod spring *

25. Pump plunger

27. Main jet

28. Main jet gasket

29. Pump dumping spring

30. Ball steel retainer

31. Steel ball

32. Set screw

33. Power piston spring

34. Power piston

35. Power piston stop

36. Spring washer

37. Power valve

38. Lifter rod

39. Snap ring

40. Slow jet sub-assy

41. Main air bleeder sub-assy

42. Guide

43. Pump discharge weight

44. Plug

45. Pump jet plug

46. Steel ball

47. Set screw

48. Valve sub-assy

49. Ring

50. Gasket

51. Carburetor body

52. Pump jet screw gasket

53. Nut plug

54. Carburetor level gage sub-assy

55. Level gage gasket

56. Level gage glass

57. Level gage clamp

Fig. 5-12 Removing Air-horn V4359

3. Remove the throttle connecting link. Loosen and remove the two screws retaining the main body to the flange , and separate the main body from the flange.

4. Air-horn disassembly.

a. Remove the float lever pin, then remove the float, needle valve push pin, spring and the needle valve.

Fig.5-14 Removing Lifter V4361 Rod & Pump Plunger

(1) Remove the snap ring, step-up rod spring and the step-up-rod from the lifter rod.

(2) Remove the "E" ring, pump plunger and the spring from the lifter rod.

b. Screw out the needle valve seat and the gasket.

c. Remove the main passage plug, gasket and the strainer.

d. Remove the power piston stopper, and then, take out the power piston and the spring.

Fig. 5-13 Removing Power V4360 Piston

5 . Carburetor main body disassembly.

Fig.5-15 Lifter Rod V4362

Components

Fig.5-15 Lifter Rod V4362

Components b. Loosen and remove the main jet (1), and the power valve (2).

c. Loosen and remove the slow jet (3) and the main air bleeder (4) .

d. Remove the screw plug (5), and invert the carburetor body to remove the pump discharge weight and the check ball.

a. Slide out the lifter rod together with the pump plunger and the metering rod. Remove the pump spring. Remove the lifter rod guide.

3. Check the float needle valve for proper seating.

To check the needle valve seating, invert the air-horn, and assemble the needle valve assembly and the float, and then suck the main fuel passage.

At this time, if any leak is present, the valve seating is not satisfactory .

Fig.5-17 Removing Main V4364 Jet

6. Screw out the idle adjusting screw and the spring..

Inspection & Repair

Wash the disassembled parts in clean gasoline, blow the fuel passages with compressed air, and remove the dirt. Wash the exterior of the parts with a soft brush.

Wash and clean the carbon deposits around the throttle valves. Never use a wire for cleaning the jets.

Air-horn

1. Inspect the air-horn for cracks, nicks or burrs at gasket surface .

2. Inspect the float for deformation, leak, damaged tabs, and worn lever pin and pin bores.

Fig.5-18 Needle Valve W6746

Inspection

4. Check the power piston for smooth movement.

5. Inspect the strainer for rust and other damage.

6. Check the choke valve for proper choking, smooth movement, and for excessive play of the choke valve shaft.

If necessary, replace the choke valve or shaft in the following manner.

a. Remove the choke valve retaining screws, and remove the choke valve.

b. Next, slide out the choke shaft together with the choke lever, choke valve relief spring, and the choke valve spring from the air-

c. Inspect the choke valve, and the shaft for bend, wear, and binding in the shaft bores of the air-horn.

Fig. 5-16 Main Body

Fig.5-17 Removing Main V4364 Jet

Fig. 5-16 Main Body o

Fig.5-19

Choke Shaft

Components d. To assemble, follow the disassembly procedures in the reverse order with the following cautions.

Fig.5-20 Pump Plunger

Components

6. Inspect the step-up-rod for bend and wear.

(1) Lubricate the sliding portion of the choke shaft with multipurpose

(2) Adjust the valve position so that it will choke firmly.

(3) After checking the choke shaft for smooth operation, rivet the screw ends slightly.

Carburetor Body

1 . Inspect the carburetor body for cracks, nicks or burrs at gasket surfaces, and stripped threads.

2. Check the power valve for smooth operation and proper seating.

3. Check the jets and air bleeder for damaged threads, damaged head slots, and damaged holes.

4. Check the pump plunger and the lifter rod for wear of sliding portion, defective leather, smooth operation with the plunger bore. Check the spring for rust and weakness.

5. Inspect the check ball and the pump discharge weight for rust, nicks or burrs.

1. Inspect the flange for cracks, nicks or burrs at gasket surfaces.

2. Check the idle adjusting screw for damaged threads, and also the seating surfaces.

Check the spring for weakness.

Fig. 5-21 Idle Adjusting W3727

Screw

3. Check the throttle valve if it closes firmly or not, and check the valve for smooth operation and excessive play of the throttle shaft. If necessary, replace the throttle shaft or the throttle valve in the following manner.

a. Remove the throttle valve retaining screws, and take out the throttle valve.

b . Loosen and remove the nut retaining the throttle lever and the fast idle lever, and remove the levers.

c. Pull out the throttle shaft from the flange.

d. To assemble, follow the disassembly procedures in the reverse order with the following cautions.

(1) Lubricate the sliding portion of the throttle shaft with multipurpose grease.

(2) Adjust the throttle valve to close firmly at fully closed position .

(3) After checking the throttle shaft for smooth operation, rivet the screw ends slightly.

Assembly & Adjustment

All gasket should be replaced upon assembly.

To assemble, follow the disassembly procedures in the reverse order. Upon assembly, the following adjustments are very important to obtain proper carburetor for all engine speeds.

Air-horn

1. When assembling the float and the needle valve, adjust the float level by bending the_ tabs on the float

There are two adjustments with the float.

One with the float at raised position and the other with the float at lowered position.

The final inspection should be performed with the level gauge glass

Fig, 5-22 Float Level X4985

Adjument

2. For the adjustment at raised position, invert the air-horn, and check the clearance between the end of the float, and the air-horn gasket surface with a gauge as shown in the illustration. To check, use the Carburetor Adjust Kit 09240-60030. The clearance should be 5.8 mm (0.23").

To obtain a correct clearance, bend the tab at (1) in figure 5-22.

Fig. 5-23 Raised Position V4366 Measurement

Fig. 5-23 Raised Position V4366 Measurement

3. For adjustment at lowered position, hold the air-horn at upright position and measure the clearance between the air-horn gasket surface and the end of the float. To check, use the Carburetor Adjust Kit 09240-60030. The clearance should be 20 mm (0.8").

To obtain a correct clearance, bend the float tabs at (2) in figure 5-22.

Fig.5-24 Lowered Position V4367 Measurement

Fig.5-24 Lowered Position V4367 Measurement

Flange

1. When assembling the throttle valve and shaft, close the throttle valve completely, and check the valve position with the slow port. If the valve position is not proper as shown in the illustration, replace the throttle valve, and the shaft.

Fig.5-25 Throttle Valve Closed

Position X4988

Fig.5-25 Throttle Valve Closed

Position X4988

2. When installing the idle adjusting screw, screw in all the way, then unscrew one and a half of a turn.

Carburetor Main Body

1. Assemble the carburetor body on the flange.

Before assembling the lifter rod and the pump plunger to the carburetor body, remove the step-up-rod from the lifter rod. After assembling the lifter rod, and the pump plunger to the carburetor body, install the throttle connecting link, and then check the height of the step-up-rod position using the Carburetor Adjusting Kit 09240-60030 as shown in the illustration.

This height should be 28.5 mm (1.12"), and if necessary , adjust by bending the throttle connecting link (1).

CAUTION:

This check should be done upon closing the throttle valve completely and not operating the throttle adjusting screw.

Fig.5-26 Step-up-rod X4989

Adjustment

Fig.5-26 Step-up-rod X4989

Adjustment

2. When installing the throttle adjusting screw, screw in until it touches the flange, and then screw in about 3/4 of a turn.

At this time, check the throttle valve position with the slow port as shown in the illustration.

To adjust the valve position, screw in or out the throttle adjusting

The final adjustment should be readjusted during engine tune-up operation .

3. After assembling the carburetor, the adjustment of the fast idle must be performed.

Close the choke valve completely , and check the opening angle of the throttle valve.

Place the angle gauge in the Carburetor Adjust Kit 09240-60030 on the throttle valve as shown in the figure 5-28.

If necessary, adjust by bending the fast idle connector.

Installation

Follow the removal procedures in the reverse order.

Check the fuel leak from the connec-

Check the throttle valve to open fully at the time when the accelerator pedal is fully depressed.

After the engine is warmed up, adjust the engine idling speed by referring to the Engine Tune-Up section.

Fig.5-28 Fast Idle G1575

Adjustment

Fig.5-28 Fast Idle G1575

Adjustment

CARBURETOR (OLD) -for FA Construction Operation

1. Pump plunger

2. Secondary main air bleeder

3. Secondary main nozzle

4. Air vent

5. Secondary small venturi

6. Pump jet

7. Choke valve

8. Primary small venturi

9. Primary main nozzle

10. Primary main air bleeder

11. Primary air bleeder No. 2

12. Economizer jet

13. Primary air bleeder No.l

14. Slow jet

15. Power piston

16. Float

17. Strainer

18. Needle valve

19. Secondary main jet

20. Check ball

21. Pump discharge weight

22. Secondary main venturi

23. High speed valve

24. Secondary throttle valve

25. Secondary bore

26. Primary main venturi

27. Primary throttle valve

28. Primary bore

29. Idle port

30. Slow port

31. Idle adjusting screw

32. Power jet

33. Power valve

34. Primary main jet

The fuel supply relations are divided into the following systems.

2. Low speed system.

3. Primary high speed system.

4. Secondary high speed system.

5. Power system.

6. Accelerating system.

7. Choke & Fast idle system.

1. Float chamber & Air vent system.

The fuel enters into the float chamber through the strainer (1) , needle valve (2), and the valve seat (3). The quantity of fuel is regulated by the needle valve opening movement from the valve seat, and also by the fuel pump pressure. Proper fuel level is maintained by the float, needle valve, and the correct fuel pump pressure. These items are very important to obtain proper performances of the carburetor .

Air vents (4) are provided to keep the float chamber with the same pressure as that of the pressure present in the air-horn, eliminating the effect of a clogged air cleaner element.

These are also connected to the air-horns of the primary, and the secondary.

A level gauge glass is installed as the cover for visual inspection of the fuel level.

Air Vents

2. Low speed system

The low speed system consists of the slow jet (1), economizer jet

(2), primary air bleeder No.l

(3) and No.2 (4), and the idle adjusting screw (5).

These are provided only in the primary side, which control the fuel discharge necessary for light engine load at low speed. Also a magnetic valve is provided in this system to prevent engine from continuous running after ignition circuit is off. The magnetic valve is operated when the ignition switch is turned on, and economizer jet opens.

When the ignition switch is turned off, the economizer jet is closed by the magnetic valve, and fuel does not discharge when the engine is at stopped condition. Therefore, the fuel does not overflow even though the temperature within the engine compartment is high.

At idle speed, air is drawn into the air-horn which enters the float chamber through the vent tube, and into the primary air bleeders. The pressure in the float chamber is maintained the same as in the air-horn.

The pressure difference between the float chamber, and the discharge ports which is due to the high manifold vacuum, forces the fuel to flow through the idle system. The fuel is forced to flow through the primary main jet, slow jet, and economizer jet into the discharge passage. The fuel is controlled through the economizer jet and the slow jet. The air entering through the primary air bleeders mixes with the fuel. The air-fuel mixture travels down the fuel passage, and is discharged through the discharging holes.

As the throttle valve opens slightly, each hole discharges the fuel by the manifold vacuum. The idle fuel discharged is controlled by the idle adjusting screw which seats in the idle port.

Fig. 5-31 Low Speed Systerr

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