Compression Check: Testing and Inspection

When checking compression pressures, ensure engine is at normal operating temperature and battery is completely charged. Remove all spark plugs and open throttle fully. Remove ignition coil harness, then install a suitable compression gauge. Crank engine and note compression gauge reading when gauge pointer is steady. Perform at least two measurements per cylinder to ensure compression readings are correct. The maximum compression difference between cylinders is 14 psi. Compression pressures should be 135-156 psi at 300 RPM.