Valve stem runout

Support the valve with " V " blocks, as shown, and check its runout with a dial gauge.

The valve must be replaced if the runout exceeds the limit. Service Limit: 0.05 mm (0.002 in)

09900-20606: Dial gauge (1/100 mm)

09900-20701: Magnetic stand 09900-21304: V-block (1/100 mm)

Place the dial gauge at right angles to the valve head face, and measure the valve head radial runout.

If it measures more than the limit, replace the valve.

Service Limit: 0.03 mm (0.001 in) 09900-20606: Dial gauge (1/100 mm) 09900-20701: Magnetic stand

09900-21304: V-block (1/100 mm)

VALVE FACE WEAR

The thickness CD decreases as the wear of the face advances.

Measure the thickness and, if the thickness is found to have been reduced to the limit, replace it.

Service Limit CD: 0.5 mm (0.02 in)

Lift the valve about 10 mm (0.39 in) from the valve seat. Measure the deflection in two directions, " X" and " Y", per­ pendicular to each other, by positioning the dial gauge as shown. If the deflection measured exceeds the limit, (see below) then determine whether the valve or the guide should be replaced with a new one.

Service Limit

Intake valves: 0.35 mm (0.014 in) Exhaust valves: 0.35 mm (0.014 in)

If the valve stem is worn down to the limit, as measured with a micrometer, where the clearance is found to be in excess of the limit indicated, replace the valve; if the stem is within the limit, then replace the guide. After replacing valve or guide, be sure to recheck the clearance.

09900-20205: Micrometer (O - 25 mm) Standard

Intake valves: 4.460 - 4.475 mm (0.1756 - 0.1762 in)

VALVE GUIDE SERVICING

• Using the valve guide remover CD, drive the valve guide out toward intake or exhaust camshaft side.

09916-43210: Valve guide remover/installer

NOTE:

* Discard the removed valve guide subassemblies.

* Only oversized valve guides are available as replacement parts. (Part No. 1 1 1 15-32C70)

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09916-34580: Valve guide reamer

09916-34542: Reamer handle

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09916-43210: Valve guide remover/installer 09916-43220: Attachment

CAUTION:

Failure to oil the valve guide hole before driving the new guide into place many result in a damaged guide or head.

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09916-33210: Valve guide reamer 09916-34542: Reamer handle

• Coat the valve seat with prussian blue uniformly. Fit the valve and tap the coated seat with the valve face in a rotating manner, in order to obtain a clear impression of the seating contact. In th is operation, use the valve lapper to hold the valve head.

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Standard

Valve seat width @): 0.7 - 0.9 mm (0.03 - 0.04 in)

If either requirement is not met, correct the seat by servicing it as follows:

VALVE SEAT SERVICING

The valve seats for both intake and exhaust valves are machined to three different angles. The seat contact surface is cut 45°.

(For U.S.A. model)

Valve seat cutter: (N-121), (N-122), (N-130), (N-131) and (N-111)

Solid pilot: (N-100-4.5)

(For the other models)

NOTE:

The valve seat contact area must be inspected after each cut.

• I nse rt th e sol id pi l ot CD with a slight rotation. Seat the pi l ot sn ugl y. I nsta l l the 45° cutter, attachment a nd T-hand le.

• Usi ng th e 45° cutter, d esca le a nd clean u p the seat wi th one or two tu rns.

• I nspect the seat by the previousl y d escri bed seat width measu rement proced u re. I f the seat is pitted or bu rned, add itiona l seat cond ition i ng with the 45° cutter is req u i red.

NOTE:

Cut only the minimum amount necessary from the seat to prevent the possibility of the valve stem becoming too close to the rocker arm for correct valve contact angle.

I f th e contact a rea is too h igh on the va l ve, or if i t is too wid e, u se the 15°/60° cutter to lower a nd na r row t he contact a rea.

I f the contact a rea is too l ow or too na rrow, use the 45° cutter to raise a nd widen t he contact a rea.

Contact area too high and too wide on face of valve

Contact area too low and too narrow on face of valve

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CAUTION:

DO NOT use lapping compound after the final cut is made. The finished valve seat should have a velvety smooth finish and not a highly polished or shiny finish. This will provide a soft surface for the final seating of the valve which will occur during the first few seconds of engine operation.

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WARNI NG:

Always use extreme caution when handling gasoline.

NOTE:

After servicing the valve seats, be sure to adjust the valve clearance after the cylinder head has been reinstalled. (see page 2-5.)

CAUTION:

* Refacing valve stem end face is permissible where the length

CD will not be reduced to less than 2.7 mm. If this length

becomes shorter than 2.7 mm, then the valve must be re­ placed.

*