IDLE SPEED | CHECK AND ADJUSTMENT
Refer to illustrations 20.3a, 30.3b and 20.3c
Before adjusting the idle speed, make sure the valve clearances, spark plug gap and breaker point gap (models so equipped) are correct.
Also, turn the handlebars back-and-forth and see if the idle speed changes as this is done. If it does, the throttle cable may not be adjusted correctly, or it may be worn out. Be sure to correct this problem before proceeding.
The engine should be at normal operating temperature, which is usually reached after 10 to 15 minutes of stop and go riding. Make sure the transmission is in Neutral.
Turn the throttle stop screw (see illustrations) until the idle speed listed in this Chapter's Specifications is obtained.
Snap the throttle open and shut a few times, then recheck the idle speed. If necessary, repeat the adjustment procedure.
If a smooth, steady idle can't be achieved, the fuel/air mixture may be incorrect. Refer to Chapter 13 for additional carburetor information.
GENERAL ENGINE OVERHAUL PROCEDURES
CYLINDER COMPRESSION | CHECK (Refer to illustration 3.5)
Among other things, poor engine performance may be caused by leaking valves, incorrect valve clearances, a leaking head gasket, or worn piston, rings and/or cylinder wall.
A cylinder compression check will help pinpoint these conditions and can also indicate the presence of excessive carbon deposits in the cylinder head.
The only tools required are a compression gauge and a spark plug wrench. Depending on the outcome of the initial test, a squirt-type oil can may also be needed.
Start the engine and allow it to reach normal operating temperature, then remove the spark plug (see Chapter 1, if necessary). Work carefully - don't strip the spark plug hole threads and don't burn your hands.
Disable the ignition by disconnecting the primary (low tension) wires from the coil (see Chapter 4). Be sure to mark the locations of the wires before detaching them.
Install the compression gauge in the spark plug hole (see illustration). Hold or block the throttle wide open.
Crank the engine over a minimum of four or five revolutions (or until the gauge reading stops increasing) and observe the initial movement of the compression gauge needle as well as the final total gauge reading. Compare the results to the value listed in this Chapter's Specifications.
