Be sure no compound enters the gap between the valve stem and guide.

• Apply a molybdenum disulfide oil to the valve stem.

• Install the valve into the cylinder head.

• Turn the valve until the valve face and valve seat are evenly polished, then clean off all compound.

To obtain the best lapping results, lightly tap the valve seat while rotating the valve back and forth between your hands.

• Apply a fine lapping compound to the valve face and repeat the above steps.

Be sure to clean off all compound from the valve face and valve seat after every lapping operation.

• Apply the Mechanic's bluing dye (Dykem) to the valve face.

• Install the valve into the cylinder head.

• Press the valve through the valve guide and onto the valve seat to make a clear pattern.

• Measure the valve seat width again.

If the valve seat width is out of specification, reface and lap the valve seat.


1. Measure:

•Stem-to-guide clearance

Stem-to-guide clearance = Valve guide inside diameter (a) -Valve stem diameter (b)

Out of specificationReplace valve guide.

Stem-to-guide clearance: Intake 0.010-0.037 mm (0.0004 - 0.0014 in)

< Limit: 0.06 mm (0.002 in)> Exhaust 0.030 - 0.057 mm

(0.00120-0.00220 in)

Replacement steps: NOTE: _

Heat the cylinder head in an oven to 100°C (212°F) to ease guide removal and installation and to maintain correct interference fit.

• Remove the valve guide using the Valve guide remover 0.

• Install the valve guide (new) using the valve guide installer (2) and valve guide remover (T).

• After installing the valve guide, bore the valve guide using the valve guide reamer (3) to obtain proper stem-to-guide clearance.

Valve guide remover:


P/N YM-01225

Valve guide installer:

P/N Y M-04017

Valve guide reamer:

Reface the valve seat after replacing the valve guide.

3. Eliminate:

•Carbon deposit (from valve face)

Pitting/Wear-^Grind the face. •Valve stem end Mushroom shape or diameter larger than rest of stemReplace.





5. Measure:

•Margin thickness (a) Out of specificationReplace.

Margin thickness:


0.8-1.2 mm (0.031

-0.047 in)


0.8-1.2 mm (0.031

•Runout (valve stem) Out of specificationReplace.



•Always replace the guide if the valve is replaced. •Always replace the oil seal if the valve is removed.

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