6-15 CYLINDER HEAD, CYLINDER AND PISTON
• If the seat width
W measured exceeds the standard value or
seat width is not uniform, refuse the seat using the seat cutter.
" Valve seat width
W:
Standard: 0.9 – 1.1 mm (0.035 – 0.043 in)
VALVE SEAT SERVICING
The valve seats
1 for both the intake valve
2 and exhaust
valve
3 are machined to three different angles. The seat con-
tact surface is cut at 45°.
NOTE:
After servicing the valve seats, be sure to check the valve clear-
ance after the cylinder head has been reinstalled. (!2-20)
INTAKE EXHAUST
Seat angle 30°, 45°, 60° 15°, 45°, 60°
Seat width
0.9 – 1.1 mm
(0.035 – 0.043 in)
←
Valve diameter 36 mm (1.4 in) 31 mm (1.2 in)
Valve guide I.D.
5.500 – 5.512 mm
(0.2165 – 0.2170 in)
←
CAUTION
The valve seat contact area must be inspected after
each cut.
Do not use lapping compound after the final cut is
made. The finished valve seat should have a velvety
smooth finish but not a highly polished or shiny fin-
ish. This will provide a soft surface for the final seat-
ing of the valve which will occur during the first few
seconds of engine operation.
CAUTION
The titanium valves are coated with an oxidized mem-
brane treatment to resist wear but the membrane tend
to be removed if lapped after valve seat servicing.
15˚
45˚
60˚
30˚
45˚
60˚
Valve seatValve seat
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