6. CYLINDER HEAD/VALVES STRYKER 125/150 Inspect the valve seat width. Service Limit: 1.8mm replace if over If the seat is too wide or too narrow or has low spots, the seat must be ground using a valve seat cutter. Valve Seat Width VALVE SEAT GRINDING Remove any roughness or irregularities from the seat using a 45° cutter. Roughness Be careful not to grind too much. Use a 37.5° cutter to remove the upper existing valve seat material. Old Seat Width 6-12