8. CYLINDER HEAD/VALVES MXU 550EXi /MXU500i Camshaft Support both ends of the camshaft with V- blocks and check the camshaft runout with a dial gauge. Service limit: 0.05 mm Inspect camshaft lobes for pitting/scratches/blue discoloration. Measure the cam lobe height. Service Limits: IN : 37.11 mm EX: 36.86 mm If any defects are found, replace the camshaft with a new one, then inspect lubrication system. Check the decompression system by turning the de-compressor cam on the exhaust camshaft. You should be able to turn the de-compressor cam clockwise smoothly, but the de- compressor should not turn counterclockwise. 8-10