5.15
Section 5
Fuel System and Governor
5
Figure 5-35. Keihin BK Two-Barrel Carburetor - Exploded View.
Governor
General
The governor is designed to hold the engine speed
constant under changing load conditions. Most
engines are equipped with a centrifugal flyweight
mechanical governor. The governor gear/flyweight
mechanism of the mechanical governor is mounted
inside the crankcase and is driven off the gear on the
camshaft. This governor design works as follows:
12. O-Ring (Fuel Bowl - Lower)
13. Drain Screw
14. Bowl Screw (4)
15. Fuel Solenoid
16. Sealing Washer
17. Float
18. Pin
19. Screw
20. Float Clip
21. Float Valve/Inlet Needle
22. Main Nozzle - Right Side
1. Carburetor Body Subassembly
2. Idle Speed Screw
3. Idle Speed Spring
4. Screw
5. Ground Lead
6. Retaining Washer
7. Slow Jet - RH Side
8. Slow Jet - LH Side
9. O-Ring (Slow Jet) (2)
10. Fuel Bowl
11. O-Ring (Fuel Bowl - Upper)
23. Main Nozzle - Left Side
24. Main Jet - Right Side
25. Main Jet - Left Side
26. Choke Dust Cap
27. Choke Shaft
28. Spring
29. Bushing
30. Choke Lever
31. Choke Plate
32. Choke Plate Screw (2)
• Centrifugal force acting on the rotating governor
gear assembly causes the flyweights to move
outward as speed increases. Governor spring
tension moves them inward as speed decreases.
• As the flyweights move outward, they cause the
regulating pin to move outward.
• The regulating pin contacts the tab on the cross
shaft causing the shaft to rotate.