Yamaha XZ550RJ 1982 Service Manual page 54

Valve guides
If oil leaks into the cylinder through a valve
due to a worn valve guide or if a valve is
replaced, the valve guide should also be
replaced.
NOTE:
The valve oil seal should be replaced whenever a
valve is removed or replaced.
1. Measure the valve guide inside diameter
with a small bore gauge. If it exceeds the
limit, replace it with an oversize valve guide.
Guide diameter (I.D.):
Limit: 6.10mm (0.24 in)
2. To ease guide removal and reinstallation
and to maintain the correct interference fit,
heat the head td 100°C (212°F). Use an
oven to avoid any possibility of head warp-
age due to uneven heating.
3. Use the valve guide remover and valve
guide installer to drive the old guide out and
drive the new guide in.
NOTE:
The valve guide oil seal should be replaced when-
ever a valve is removed or replaced.
1. Valve guide installer
4. After installing the valve guide, use the
6mm (0.24 in) reamer (special tool) to ob-
tain the proper valve guide-to-valve stem
clearance.
5. After installing the valve guide in the cylin-
der head, the valve seat must be recut. The
valve should be lapped to the new seat.
Valve seat
1. The valve seat is subject to severe wear.
Whenever the valve is replaced or the valve
face is resurfaced (see CAUTION), the
valve seat should be resurfaced at a 45°
angle. If a new valve guide has been in-
stalled, the valve seat must be recut to
guarantee complete sealing between the
valve face and seat.
2. Valve guide remover
54