3. INSPECTION/ADJUSTMENT MXU 550EXi/MXU500i Compression Gauge CYLINDER COMPRESSION Warm up the engine before compression test. Remove the spark plug. Insert a compression gauge. Open the throttle valve fully and push the starter button to test the compression. Cylinder compression : 15 kg/cm If the compression is low, check for the following: - Leaky valves - Valve clearance too 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. Upper Level ENGINE OIL OIL LEVEL Place the machine on a level place. Warm up the engine for several minutes and stop it. Run the engine for 23 minutes and check the oil level after the engine is stopped for 23 minutes. Check the oil level through the inspection Lower Level Inspection Window window. The oil level should be between the maximum (H) and minimum (L) marks. If the level is low, add oil to raise it to the proper level. Recommended engine oil: KYMCO 4-stroke oil or equivalent motor oil API service classification: SJ Viscosity: SAE 5W30 Other viscosities shown in the chart may be used when the average temperature in your riding area is within the indicated range. 3-12