Linhai 2005 ATV 260, Service Manual

Page: 66 / 341

CHAPTER 3A ENGINE
260/ 300 cc ATV SERVICE MANUAL07.0
CHAPTER 3 ENGINE PAGE. 3A- 29
z
Valve seat width
○
a
Out of specification
→
Reface the valve seat.
Valve seat width:
Intake:
0.9-1.1mm
<Limit:1.6mm>
Exhaust:
0.9-1.1mm
<Limit:1.6mm>
Measurement step:
z
Apply Mechanic’s blueing dye (Dykem)
c
to
the valve face.
z
Install the valve into the cylinder head.
Press the valve through the valve guide and
onto the valve seat to make a clear pattern.
z
Measure the valve seat width. Where the valve
seat and valve face made contact, blueing will
have been removed.
z
If the valve seat is too wide, too narrow, or the
seat is not centered, the valve seat must be
replaced.
4. Lap:
z
Valve face
z
Valve seat
NOTE:
After replacing the valve seat, valve and valve
guide, the valve seat and valve face should be
lapped.
Lapping steps:
z
Apply a coarse lapping com pound
○
a
to the
valve face.
CAUTION:
Do not let compound enter the gap between the
valve stem and the guide.
z
Apply molybdenum disulfide oil to the valve
stem.
z
Install the valve into the cylinder head.
z
Turn the valve until the valve face and valve
seat are evenly polished, then clean off al com
pound.
NOTE:
For best lapping results, lightly tap the valve
seat while rotating the valve back and forth
between your hand.
z
Apply a fine lapping compound to the valve