Replacing Valve Seat Inserts

As valves and seats are refaced from time to time, valve seats widen and valves seat in lower position when fully closed. Passage around valve when fully open is restricted and the valve will tend to float as spring tension is reduced. To determine whether a valve seat requires grinding or a new valve seat insert, check the table in Fig. 3B-9. If measurement B exceeds maximum limit of 1.420 in., a valve seat insert should be installed. A special gage is available under Part No. 96489-63 which is used to measure this dimension. The tool consists of a gage valve and gage which is placed over the valve stem. If top end of gage valve stem is between steps on gage, the valve seat location Is satisfactory.

Cylinder heads may be returned to factory through authorized Harley-Davidson dealer for valve seat insert replacement. Heads are bored out to remove old seats, and new seats are pressed into place.

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