Caution: Before making any carburetor adjustments, check that spark plug gaps are correct and that all electrical connections and vacuum hoses are securely connected and fully functional. An accurate tachometer and exhaust gas analyzer must be used to perform carburetor adjustments.
Check the idle speed adjustment and the quality of the fuel mixture. Leave the tachometer connected. The idle speed should be. That is adjusted before adjusting the fast idle speed. Warm the engine to operating temperature and remove the air filter.
Partially open the throttle valve, then close it until the adjusting screw is positioned on the third (middle) stage of the fast idle stepped washer and the throttle is clear. If adjustment is required, turn the fast idle speed adjusting screw clockwise to decrease the speed or counterclockwise to increase it (see Fig. 4A.22).
Start the engine and, without touching the accelerator pedal, check the idle speed and fast idle speed. Turn off the engine, disconnect the tachometer with the fuel mixture quality meter and install the air cleaner.