ENGINE SPEED ADJUSTMENT
GM
4Y
-
4 Y . G M Engine
Tachometer Tachometer
Idle up and Idling Speed Inspection and Adjustment 1.
Warm up the engine.
Coolant temperature: 80°C (176OF) or above Engine oil: 70°C (158OF) or above Hydraulic oil temperature: 50°C (122OF) or above Auto choke cancellation
connector
2. 3.
Install the engine tachometer. lnspect and adjust the idle up speed. ( 1) Disconnect the idle up actuator hose and inspect the idle up speed.
4Y: 1 2 5 0 & 25 rpm GM: 1 0 5 0 & 5 0 rpm
(2) Turn the adjusting screw (A) t o adjust the idle up speed. Increasing the speed: Clockwise turn Decreasing the speed: Counterclockwise turn (3) Connect the idle up'actuator hose. 4.
lnspect and adjust the idling speed. ( 1) lnspect the idling speed.
Idling speed 4Y: 7 5 0 GM: 7 0 0
+zO rpm +zO rpm
(2) Turn the idle adjusting screw (B) t o adjust the idling speed. (3) If the speed cannot be decreased b y turning the adjusting screw (B), make adjustment as follows:
@
Raise the coolant temperature when the auto choke cam is in contact with the throttle lever roller.
@ When the idle up actuator rod is in contact w i t h the adjusting screw (A), turn the adjusting screw counterclockwise.