EM-46 ENGINE MECHANICAL — Cylinder Head (e) Check the surface of the valve stem tip for wear. If the valve stem tip is worn, regrind it with grinder or replace the valve if necessary. NOTICE: Do not grind off more than minimum overall length (See page EM-45). 12. INSPECT AND CLEAN VALVE SEATS (a) Using a 45° cutter, resurface the valve seats. Remove only enough metal to clean the seats. (b) Check the valve seating position. Apply a thin coat of prussian blue (or white lead) to the valve face. Install the valve. Lightly press the valve against the seat. Do not rotate the valve. (c) Check the valve face and seat for the following: • If blue appears 360° around the face, the valve is concentric. If not, replace the valve. • If blue appears 360° around the valve seat, the guide and seat are concentric. If not, resurface the seat. • Check that the seat contact is on the middle of the valve face with the following width: 1.0 — 1.4 mm (0.039 — 0.055 in.) If not, correct the valve seat as follows: • If seating is too high on the valve face use 30° and 45° cutters to correct the seat. • If seating is too low on the valve face, use 60° and 45° cutters to correct the seat.