TOHATSU BFT115A Service Manual page 447

Using 32° cutter, remove the top edge of the existing
valve seat material.
Using 60° cutter, remove the bottom edge of the old
seat.
Use 45° cutter and cut the seat to the proper width.
STANDARD:
IN/EX: 1.25 – 1.55 mm (0.049 – 0.061 in)
After resurfacing the seats, inspect for even valve
seating (page 14-46).
If the contact area is too high on the valve, the seat
must be lowered using a 32° flat cutter, then adjust the
width using the 45° cutter.
If the contact area is too low on the valve, the seat must
be raised using a 60° inner cutter, then adjust the width
using the 45° cutter.
CYLINDER HEAD
OLD SEAT WIDTH
1.25 – 1.55 mm
(0.049 – 0.061 in)
CONTACT TOO HIGH
CONTACT TOO LOW
32°
OLD SEAT WIDTH
60°
45°
OLD SEAT
WIDTH
32°
OLD SEAT
WIDTH
60°
14-55