Sym Mio 50 Service Manual page 80

Caution
If clearance between valve stem and valve
guide exceeded service limit, check whether
the new clearance that only replaces new
valve guide is within service limit or not. If
so, replace valve guide.
Correct it with reamer after replacement.
If clearance still exceeds service limit after
replaced valve guide, replace valve stem too.
Caution
It has to correct valve seat when replacing
valve guide.
Valve stem replacement
Heat up cylinder head to 100~150 ¢ J
plate or toaster.
Caution
Do not let torch heat cylinder head directly.
Otherwise, the cylinder head may be
deformed as heating it.
Wear on a pair of glove to protect your hands
when operating.
Hold the cylinder head, and then press out old
valve guide from combustion chamber side.
Special Service Tool:
Valve guide driver: 5.0mm
Caution
Check if new valve guide is deformation after
pressed it in.
When pressing in the new valve guide,
cylinder head still have to be kept in 100~150
¢ J .
Adjust the valve guide driver and let valve guide
height is in 13mm.
Press in new valve guide from rocker arm side.
Special Service Tool:
Valve guide driver: 5.0mm
Wait for the cylinder head cooling down to room
temperature, and then correct the new valve guide
with reamer.
Caution
Using cutting oil when correcting valve guide
with a reamer.
Turn the reamer in same direction when it be
inserted or rotated.
Correct valve seat, and clean up all metal residues
from cylinder head.
Special Service Tool: Valve reamer: 5.0mm
To this chapter contents
with heated
13 mm
(0.15in)
Valve guide driver 5.0mm
6. Cylinder Head / Valve
Valve guide
driver 5.0mm
Valve guide
driver 5.0mm
6-11