MAINTENANCE MANUAL OF ENGINE
35
4.4 Correcting the valve seat
Special tools:
Reamer for intake valve seat
Reamer for exhaust valve seat
Guide bar, used along with the reamer
Handle set used along with the reamer
1. Do not move the valve seat before installing the
new valve guide.
2. Insert the guide bar through the valve guide.
Then fix the guide bar.
3. Select a proper reamer. Adjust the reamer blade
so that the expected reaming diameter is equal to
the valve seat diameter. Install the reamer to the
guide bar. Install the handle to the guide bar. Be
sure that the reamer is not below the valve seat.
Otherwise damage could be caused to the reamer
blade.
4. Carefully rotate the handle clockwise. The metal
removed shall be adequately minimal to ensure the
integrity of the valve seat. The valve seat hole shall
be as small as possible.
5. Upon completion of the reaming, remove the
reamer and guide bar. Remove the chips around the
valve seat and guide bar.
6. Install the valve stem. Slightly grind the valve
head and valve seat.
7. Check whether the valve depth is within the per-
missible limit.
Attention: In case of serious damage or wear of
valve seat, thus great difficulty in correction by
reaming, install a valve seat insert.