3. INSPECTION/ADJUSTMENT DOWNTOWN 125i CYLINDER COMPRESSION Warm up the engine before compression test. Remove the center cover and spark plug cap. Remove the spark plug . Insert a compression gauge. Open the throttle valve fully and push the starter button to test the compression. Compression: Downtown125i:15 kg/cm If the compression is low, check for the following: Leaky valves Valve clearance too small Leaking cylinder head gasket Worn pistons Worn piston/cylinder If the compression is high, it indicates that carbon deposits have accumulated on the combustion chamber and the piston head. DRIVE BELT Remove the left crankcase cover. Inspect the drive belt for cracks or excessive wear. Replace the drive belt with a new one if necessary and in accordance with the Maintenance Schedule. 3-16