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The idle air bypass screw is located in the throttle valve as shown in Fig. 7-10. Adjusting the screw changes the amount of air which is allowed to bypass the throttle plate, which in turn changes idle speed.

When checking or adjusting idle speed, the crankcase breather hose should be attached normally, and the dipstick should be fully seated, all the way into the dipstick tube.


Ignition timing should be adjusted to specifications, as described in IGNITION before making final adjustments to idle speed.

Fig. 7-10. Idle air bypass adjusting screw (1) on throttle valve housing. Turning screw clockwise will decrease idle speed; turning screw counterclockwise will increase idle speed.

To adjust idle speed, disconnect the harness connector from the coolant temperature sensor. As shown in table p, the idle speed should be 950±50 rpm. If not, turn the idle air bypass adjusting screw as shown in Fig. 7-10 to adjust the idle speed to 950±25 rpm. When the coolant temperature sensor harness connector is reconnected, the idle speed should drop to 800±50 rpm. If not, check the idle air stabilizer valve or the coolant temperature sensor and its wiring.

Table p. Idle Specifications (Digifant II)

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