Yanmar 6LPA-STP2 Service Manual page 105

Cylinder Head
12/05
• If the seat position on the valve face is too high
(Figure 5-34), refinish the valve seat using
cutters having angles as listed in the chart
below and a 45° cutter.
Valve Seat Angle Chart
Intake
70°
Figure 5-34
Figure 5-34
1 – 45° Angle
2 – (See Valve Seat Angle Chart)
4. Hand-lap the valve and valve seat using an
abrasive compound (Figure 5-35).
Figure 5-35
Figure 5-35
5. After lapping, clean the valve and valve seat.
6LPA Service Manual
Exhaust
65°
(2)
(1)
0004959
0004960
© 2007 Yanmar Marine International
Valve Spring Inspection
1. Measure the straightness of the valve spring
using a square:
• Maximum deviation: 2.0 mm (0.079 in.)
(Figure 5-36, (1))
If the measured deviation exceeds the specified
maximum, replace the valve spring.
Figure 5-36
(1)
Figure 5-36
2. Measure the free length of the valve spring
using calipers (Figure 5-37).
• Yellow Mark: 49.6 mm (1.953 in.)
• Blue Mark: 49.6 mm (1.953 in.)
If the measured free length is not within
specifications, replace the valve spring.
Figure 5-37
Figure 5-37
ENGINE
0004961
0004962
5-25