Checking The Valves And Valve Guides

The following procedure applies to all of the valves and valve guides. 1. Measure: • valve-stem-to-valve-guide clearance

Valve-stem-to-valve-guide clearance = Valve guide inside diameter @ -Valve stem diameter ©

Out of specification guide.

Replace the valve

Valve-stem-to-valve-guide clearance Intake

0.010 - 0.037 mm (0.0004 - 0.0015 in) <Limit>: 0.08 mm (0.0031 in) Exhaust

0.025 - 0.052 mm (0.0010 - 0.0020 in) <Limit>: 0.10 mm (0.0039 in)

To ease valve guide removal and installation, and to maintain the correct fit, heat the cylinder head to 100oC (212° F) in an oven.

a. Remove the valve guide with the valve guide remover ®.

b. Install the new valve guide with the valve guide installer (2 and valve guide remover c. After installing the valve guide, bore the valve guide with the valve guide reamer (3 to obtain the proper valve-stem-to-valve-guide clearance.

After replacing the valve guide, reface the valve seat.

Valve guide remover (4 mm, 0.16 in)

90890-04111, Valve guide installer (4 mm, 0.16 in)

90890-04112, Valve guide reamer (4 mm, 0.16 in) 90890-04113, YM-04113

3. Eliminate:

• carbon deposits

(from the valve face and valve seat)

Pitting/wear ^ Grind the valve face.

Mushroom shape or diameter larger than the body of the valve stem ^ Replace the valve.

5. Measure: • valve margin thickness @ Out of specification ^ Replace the valve.

Valve margin thickness 0.6 - 0.8 mm (0.0236 - 0.0315 in) <Limit>: 0.5 mm (0.02 in)

6. Measure: • valve stem runout Out of specification

Replace the valve.

►When installing a new valve, always replace the valve guide.

► If the valve is removed or replaced, always replace the oil seal.

Valve stem runout

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