TOHATSU BFT115A Service Manual page 446

CYLINDER HEAD
VALVE SEAT RECONDITIONING
Clean the intake and exhaust valves thoroughly to
remove carbon deposits.
Apply a light coat of Prussian Blue to each valve seats.
Tap the valve against the valve seat several times
without rotating the valve, to check for proper valve seat
contact using a commercially available valve lapper (1).
Using a 45° cutter, remove enough material to produce
a smooth and concentric seat. Follow the valve seat
cutter manufacturer's instructions.
Turn the cutter clockwise, never counterclockwise.
Continue to turn the cutter as you lift it from the valve
seat.
TOOLS:
Valve seat cutter, 32°
38.5 mm [IN] (1)
Valve seat cutter, 32°
33 mm [EX] (2)
Valve seat cutter, 45°
35 mm [IN] (3)
Valve seat cutter, 45°
33 mm [EX] (4)
Valve seat cutter, 60°
37.5 mm [IN] (5)
Valve seat cutter, 60°
30 mm [EX] (6)
Cutter holder, 5.5 mm (7)
Use a 45° cutter, remove the roughness or irregularities
from the seat.
14-54
(3)
07780-0012400
07780-0012900
07780-0010400
07780-0010800
(1) (2)
07780-0014100
07780-0014000
07781-0010101
45°
(4)
32°
(5)
(7)
ROUGHNESS
(1)
60°
(6)
45°