Necessary tools:
1. A set of feeler gauges (metric) that includes gauges in the necessary range for intake and exhaust valves.
2. A set of metric combination wrenches to loosen the valve adjusters' lock nuts.
3. A flathead screwdriver or small pry tool to adjust the valve clearance.
4. A spark plug wrench to remove and reinstall the spark plug.
5. An engine cover gasket (if necessary).
Procedure:
1. Prepare the Engine:
- Disconnect the spark plug cap from the spark plug.
- Remove the spark plug using the spark plug wrench.
2. Locate TDC (Top Dead Center):
- Gently rotate the engine using the kick starter or rear wheel (in gear) until you feel maximum compression resistance (when the piston is at TDC).
- Align the "T" mark on the engine's flywheel/alternator cover with the index line. This indicates that the piston is at TDC on the compression stroke.
3. Check Intake Valve Clearance:
- Locate the intake valve adjuster with the word "IN" marked on it. It is usually closer to the front of the engine.
- Slightly loosen the lock nut near the adjuster using a combination wrench.
- Insert a feeler gauge of appropriate thickness between the valve stem and the adjuster surface. The correct gap/clearance is specified in your motorcycle's service manual (typically between 0.10-0.13 mm).
- Use a flathead screwdriver to adjust the clearance by either tightening or loosening the adjuster screw until the feeler gauge fits without any resistance or with a slight drag.
- Retighten the lock nut.
4. Check Exhaust Valve Clearance:
- Locate the exhaust valve adjuster, usually marked with the letter "E," typically closer to the rear of the engine.
- Follow the same procedure as described for the intake valve to check and adjust the exhaust valve clearance.
5. Reinstall Spark Plug:
- Reinstall the spark plug into the engine and reconnect the spark plug cap.
6. Repeat Steps 2-5 for the Other Cylinder (if applicable):
- If your Yamaha 135LC has two cylinders, repeat steps 2-5 for the second cylinder.
7. Engine Cover Gasket (if required):
- If you removed the engine's valve cover to access the valve adjusters, replace the cover gasket and tighten the cover bolts securely to prevent oil leaks.
Remember, the exact specifications and procedures for valve clearance adjustment can vary depending on the specific year and model of your motorcycle. Always refer to your motorcycle's official service manual for precise information and detailed instructions.
