8. CYLINDER HEAD/VALVES MXU 500 IRS Cam Chain Slipper INSPECTION Cam chain guide Inspect the cam chain slipper surface of the cam chain guide for wear or damage. Camshaft Holders Camshaft holder Always replace the camshaft holder and cylinder head in pairs Inspect the camshaft surface of each camshaft holder for scoring, scratches, or evidence of insufficient lubrication. Stop Pin Check the stop pin spring on the exhaust camshaft holder for damage. Replace the stop pin assembly with a new one if the spring is damage. 8-9