Gasoline Engines

Ensure engine oil is correct viscosity and at proper level. Ensure battery is fully charged. Check compression with engine at normal operating temperature. All spark plugs removed (on dual plugs, remove exhaust side only), throttle valves wide open and at normal cranking speed.

With ignition switch in OFF position and using an auxiliary starter switch, crank engine at least 5 compression strokes and record highest reading. Repeat test on each cylinder. Compression pressures are within specification if the lowest reading cylinder is within 25% of highest reading cylinder.