Carburetor

1. Warm up the engine fully.
2. Make sure that the idling speed and ignition timing are within specifications.


IGNITION TIMING: 2° BTDC

IDLE SPEED: 850 rpm

Fig. 13 Disabling vacuum advance:

3. Remove the vacuum hose from the distributor vacuum control unit and plug the hose Fig. 13.

Fig. 14 Centrifugal spark advance curve:

4. While gradually increasing engine rpm, check changes in ignition timing with a timing light Fig. 14.

Excessive advance: Governor spring is fatigued (If the governor spring is broken, the initial advance is very quick and high).

Insufficient advance: Governor weight or cam is not operating properly.