Valve, Intake/Exhaust

MARGIN THICKNESS
IN 0.8 - 1.2 mm {0.032 - 0.047 inch}
EX 1.2 - 1.8 mm {0.048 - 0.070 inch}

NOTE: Check the valve head margin thickness. Replace the valve if necessary.

VALVE LENGTH
Standard:
IN 121.31 mm {4.7760 inch}
EX 122.63 mm {4.8279 inch}
Minimum:
IN 120.91 mm {4.7602 inch}
EX 122.23 mm {4.8122 inch}

NOTE: Measure the valve length. Replace the valve if necessary.





VALVE STEM DIAMETER
IN 6.970 - 6.985 mm {0.2745 - 0.2750 inch}
EX 8.025 - 8.040 mm {0.3160 - 0.3165 inch}

NOTE: Measure the valve stem diameter in X and Y directions at three points (A, B and C) as shown. Replace the valve if necessary.









SEAT CONTACT WIDTH
Width 1.2 - 1.6 mm {0.048 - 0.062 inch}

NOTES:
- If the valve seating position on the valve face is too high, correct the valve seat with a 65° cutter.





- If the valve seating position on the valve face is too low, correct the valve seat with a 35° (IN) or 15° (EX) cutter.
- Seat the valve to the valve seat with a lapping compound.

VALVE STEM PROTRUDING LENGTH
Check the sinking of the valve seat. Measure the protruding length (dimension L) of the valve stem.

Dimension L
IN 50.5 mm {1.988 inch}
EX 49.5 mm {1.949 inch}





If L is as below, it can be used as it is.

Dimension L
IN 50.5 - 51.0 mm {1.989 - 2.007 inch}
EX 49.5 - 50.0 mm {1.949 - 1.968 inch}




If L is more than below, replace the cylinder head.

Dimension L
IN 51.1 mm {2.012 inch}
EX 50.1 mm {1.972 inch}