Service Manual

INSPECTION AND REPAIR OF BASIC ENGINE
6-6
1.7 Replacing valve seat
(1) To remove the valve seat, weld a stud to the valve seat
as illustrated. Then, insert a rod into the valve guide
hole from the top of the cylinder head, and press out the
valve seat with the rod.
Note: Be careful not to allow spatters to adhere to the
machined surface of the cylinder head during
welding.
(2) Before inserting a new valve seat, measure valve seat
fitting bore diameter and valve seat outside diameter to
make sure the interference meets the specified value.
(3) Cool the valve seat at least for four minutes in liquid
nitrogen before fitting it into the cylinder head that is
kept at room temperature.
(4) Fit the cold valve seat into the cylinder head using a
insert caulking tool.
Replacing valve seat
Valve seat fitting bore
Driving in valve seat
Valve seat
Weld
Stud
Shaft
8 ± 0.1 [0.31 ± 0.004]
8 ± 0.1 [0.31 ± 0.004]
2 ± 0.1 [0.08 ± 0.004] 2 ± 0.1 [0.08 ± 0.004]
45°
45°
ø46
+0.025
0
[1.81
+0.0010
0.00
]
ø37
+0.025
0
[1.46
+0.0010
0.00
]
Inlet Exhaust
Unit: mm [in.]
Insert caulking tool
(Inlet)
P/N:36791-00200, (Exhaust) P/N:34491-03020