Valve Seating Surface Outside Diameter

Inlet 28.3 ~ 28.5 mm (1.114 ~ 1.122 in.)

Exhaust 24.0 ~ 24.2 mm (0.945 ~ 0.953 in.)

NOTE

О The valve stem and guide must be in good condition, or this check will not be valid.

• If the valve seating pattern is not correct, repair the seat (see Valve Seat Repair).

• Measure the seat width [E] of the portion where there is no build-up carbon (white portion) of the valve seat with a vernier caliper.

• If the width is too wide, too narrow or uneven, repair the seat (see Valve Seat Repair).

[F] Good

[G] Too Wide
[H] Too Narrow
[J] Uneven

Valve Seating Surface Width

Inlet 0.5 ~ 1.0 mm (0.020 ~ 0.039 in.)

Exhaust 0.5 -1.0 mm (0.020 ~ 0.039 in.)

ENGINE TOP END 5-27

Valves

Measuring Valve-to-guide Clearance (Wobble method)

If a small bore gauge is not available, inspect the valve guide wear by measuring the valve to valve guide clearance with the wobble method, as indicated below.

• Insert a new valve [A] into the guide [B] and set a dial gauge against the stem perpendicular to it as close as possible to the cylinder head mating surface.

• Move the stem back and forth [C] to measure valve/valve guide clearance.

• Repeat the measurement in a direction at a right angle to the first.

• If the reading exceeds the service limit, replace the guide.

NOTE

○The reading is not actual valve/valve guide clearance because the measuring point is above the guide.

Standard: Inlet Exhaust Service Limit: Inlet Exhaust

Valve/Valve Guide Clearance (Wobble Method)

0.02 ∼ 0.08 mm (0.0008 ∼ 0.0032 in.) 0.07 ∼ 0.14 mm (0.0028 ∼ 0.0055 in.)