3.9 carburetor
a.
Idle speed adjustment
1. Run the engine at idle until it reaches normal operating temperature.
2. Turn the throttle stop screw to obtain the standard idle speed.
Standard idle speed
2 100 ± 150 rpm (HRD535/K1/K2)
1 700 ± 150 rpm (HRA536 - HRD536/K1/K2)
b. Pilot screw adjustment
CAUTION:
•
Damage the pilot screw seat will occur if the pilot screw is tightened against the seat.
1. If the pilot screw has been removed or replaced, turn the pilot screw clockwise until it
seats lightly. Then turn the pilot screw to initial setting.
Initial pilot screw setting
HRD535/K1/K2: 1 - 1/2 turns out
HRA536 - HRD536/K1/K2: 1 - 5/8 turns out
2. Run the engine outdoor at idle speed until it reaches normal operating temperature.
3. Turn the pilot screw in or out to obtain the highest idle speed. Generally, the correct
adjustment is obtained by using the values provided above.
4. Adjust the specified idle speed by turning the throttle stop screw.
Specified idle speed
2 100 ± 150 rpm (HRD535/K1/K2)
1 700 ± 150 rpm (HRA536 - HRD536/K1/K2)
[1]
THROTTLE STOP SCREW
[2]
PILOT SCREW
3.10 Governor
1. Loosen the governor arm nut, and move the governor arm to fully open the throttle
valve.
2. With the governor arm held in the fully open position, turn the governor arm shaft in the
same direction as far as it will go, and tighten the nut.
3. Check to be sure the governor arm and throttle valve move freely.
4. After adjustment, adjust the maximum engine speed (ch. 3.4b).
[3]
GOVERNOR ARM
[4]
NUT
[5]
GOVERNOR ARM SHAFT
- 29 -
HRA536 - HRD535 - HRD536
[1]
[2]
[3]
[5]
[4]
- MAINTENANCE