Section 5 Fuel System and Governor Adjusting Low Idle Speed (RPM) Setting 1. Start the engine and run at half throttle for 5 to 10 minutes to warm up. The engine must be warm before making final low idle speed (RPM) adjustment. Check that the throttle and choke plates can fully open. 2. Place the throttle control into the ‘‘ idle slow ’’ position. 3. Set the low idle speed to 1200 RPM* (±75 RPM) by turning the low idle speed adjusting screw** in or out . Check the speed using a tachometer. * NOTE: The actual low idle speed depends on the application. Refer to the equipment manufacturer’s recommendations. The low idle speed for basic engines is 1200 RPM.
** Some early models contained an adjusting cable and knob attached to the adjusting screw. See Figure 5-3. Figure 5-3. Carburetor with Adjusting Cable on the Low Idle Speed Adjustment Screw (Early Models). 5.5 Fuel Shut-off Solenoid Adjusting Cable Low Idle Speed Screw 5