1. Preparation:
- Ensure the engine is cold.
- Disconnect the spark plug wires and lay them aside.
- Remove the valve cover.
2. Locating Top Dead Center (TDC):
- Rotate the engine clockwise until the "T" mark on the left side of the flywheel aligns with the pointer. This indicates TDC.
3. Measuring Valve Clearances:
- Using a feeler gauge, measure the clearance between the cam lobe and the top of the valve stem for both the intake and exhaust valves. The specified clearances are usually mentioned in the service manual (typically around 0.15 mm for intake and 0.20 mm for exhaust).
- Clearance is measured by the feeler gauge fitting between the valve stem and the cam lobe without force.
4. Adjusting the Valves:
- If the valve clearance is not within specifications, you will need to adjust it using a screwdriver and wrench.
- Hold the lock nut (located next to the valve adjuster screw) with a wrench while turning the adjuster screw with a screwdriver.
- Once adjusted, recheck the clearance using the feeler gauge.
- Repeat the adjustment process for the remaining valve(s) as necessary.
5. Reassembly:
- Once all valves are adjusted to the correct clearance, reinstall the valve cover and reconnect the spark plug wires.
Remember, valve adjustment is a critical task that requires precision. If you're not experienced with engine work or unsure about any step, it's best to consult a professional mechanic or refer to the specific service manual for your YFZ 450 model.
