Service manual

Page 48 of 151

6-7 Valve Seat Inspection and

Service

• Clean up any carbon deposits on the intake and

exhaust valves.

• Apply emery carefully onto valve contact face.

• Grind the valve seat with a rubber hose or other

manual grinding tool.

• Do not let emery enter between the valve stem

and valve guide.

• Clean up the emery when finished, and apply

engine oil onto the contact faces of valve and

valve seat.

• Remove the valve and check its contact face.

• Replace the valve if the valve seal is rough, worn out,

or does not come into contact with the valve seat

• If the valve seat is too wide, narrow, or rough,

adjust or replace it.

Valve seat width

Service limit: 1.6mm

• Check the condition of the valve seat surface.

Valve seat grinding

• The worn valve seat has to be ground with a valve

seat chamfer cutter. Refer to operation manual for

the valve seat chamfer cutter.

• Use a 45° valve seat chamfer cutter to cut any rough

or uneven surfaces from the valve seat.

• After valve guide had been replaced, it has to be

ground with a 45° valve seal chamfer cutter to

correct its seat face.

• Use 32° cutter to cut the quarter upper parts out.