6. 4-STROKE: CYLINDER HEAD/VALVES VITALITY 50 O-ring Check the insulator and O-rings for wear or damage. ASSEMBLY Install the valve spring seats and oil seal. Be sure to install new oil seal. Lubricate each valve with engine oil and insert the valves into the valve guides. Install the valve springs and retainers. Compress the valve springs using the valve spring compressor, then install the valve cotters. · When assembling, a valve spring compressor must be used. · Install the cotters with the pointed ends facing down from the upper side of the cylinder head. Special Valve Spring Compressor E040 Tap the valve stems gently with a plastic hammer for 23 times to firmly seat the cotters. Be careful not to damage the valves. 6-13