The following steps are taken to decarbonise the engine :
Remove the exhaust muffler.
- Disconnect the spark plug.
- Remove the intake pipe bolt.
- Loosen the bolt detaching the left side cover from the cylinder head.
- Remove the bolt and left side cover.
- Remove the gearshift pedal.
- Remove the left crankcase cover.
- Rotate the generator rotor counterclockwise and align the "T" mark on the generator rotor with the index mark on the left crankcase.
- Make sure that the "O" mark on the cam sprocket is aligned with the index mark on the cylinder head cover.
- Remove the cam sprocket bolts.
- Remove the cam chain by lifting it up with the screw driver.
- Remove the cam sprocket.
- Remove the cylinder head nuts.
- Remove the cylinder head cover.
- Remove the 6mm bolt attaching the cylinder head and cylinder.
- Remove the cylinder head.
- Remove the spark plug.
- Check the spark plug for cracks at the outer and inner insulator.
- Remove the valve adjuster hole caps.
- Remove the bolts and the cylinder head right side cover.
- Screw an 8 mm bolt to the rocker arm shaft and pull out each rocker arm shaft.
- Remove the rocker arm.
- Remove the cam shaft.
- Compress the valve spring compressor and remove the retainer, valve spring and valve.
- Remove the carbon deposits from the combustion chamber.
- Remove any gasket material from the contact face of the cylinder head.
- Clean both intake and exhaust valves thoroughly to remove carbon deposits.
- Apply a light coating of valve grinding paste to each valve face. Lap each valve and seat using a rubber hose or other hand-lapping tools.
- Remove the valve and inspect the face.
- Measure the valve seat.