For 1990-2009 cars

1. Inspect the valve.
2. Inspect the valve or stem for abrasion, burn, or bending. Replace as necessary.
3. Inspect the edge of each valve for abrasion. Some uneven abrasion would be made on the edge because the rocker arm gets contacted at this surface when operating.
4. Repair the section within 0.05 mm (0.002 in) as required, or replace the valve if more modification is required (a).
5. Measure the deviation to the rotating direction (1) using a dial gage and the V block by turning the valve slowly.

Specification
The deviation limit of the valve head to the rotating direction is within 0.08 mm (0.0031 in).

6. If the measured valve exceeds the limit, replace the valve.

Caution: Refer to Safety Glasses Caution in the Preface section.

7. Clean the valve and the valve seat. Apply red stamping ink thinly to the contacting surface of the valve seat. Inspect the fitting after installing the valve unit.
8. Inspect the contact width (a) on the surface of the valve seat.

#### Specifications

• | The intake is 1.46-1.66 mm (0.0575-0.0654 in).

• | The exhaust is 1.46-1.66 mm (0.0575-0.0654 in).

9. Repair by grinding and cutting off the valve seat. Lap it if the contacting width is uneven or out of the specified range (1).

Important: Upon cutting, take care of the contact width. Finish the cutting by gradually reducing the power so that there is no cutting mark on the surface.

10. When applying a seat cutter, use one with a smaller angle first. Increase the angle of the cutter up to the light and final modification of the contact. Finish the contact surface with the cutter at 45 degrees.
11. Lap both intake (1) and the exhaust (2) sides in 2 stages:

• | First stage - normal lap

• | Second stage - fine lap