2. INSPECTION/ADJUSTMENT NEXXON 50 IGNITION TIMING The CDI unit is not adjustable. If the ignition timing is incorrect, check the ignition system. Remove the ignition timing eye hole cap on the left crankcase cover. Eye Hole Check the ignition timing with a timing light. When the engine is running at idle speed, the ignition timing is correct if the index mark on the left crankcase cover aligns with the "F" mark on the flywheel. Timing Light "F" Mark CYLINDER COMPRESSION Warm up the engine before compression test. Stop the engine, then remove the spark plug and insert a compression gauge. Open the throttle valve fully and crank the engine with the starter motor or kick lever. Measure the compression. Compression: 13 2kg/cm Compression Gauge If the compression is low, check for the following: Leaky valves Valve clearance to small Leaking cylinder head gasket Worn piston rings Worn piston/cylinder If the compression is high, it indicates that carbon deposits have accumulated on the combustion chamber and the piston head. 2-6