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DISASSEMBLY, REASSEMBLY, INSPECTION, AND MAINTENANCE 3-35
Valve System
Valve Seat Inspection and Lapping
A prerequisite for inspecting the valve seat contact is that the valve
guide and the valve stem are normal.
•
Apply a thin layer of fine lapping compound on the contact surface of
the valve.
•
Using a lapper [A], lap the valve against the seat by rotating the valve.
•
Pull out the valve and inspect whether there is an even contact at the
valve seat along its entire circumference. If not, lap the valve and the
valve seat.
•
Lap 8 to 10 times and inspect the contact each time. Repeat this
process until there is contact along the entire circumference.
•
After completing the lapping, completely wash off the compound from
all parts and allow the cylinder head to dry.
A: Lapper
1. Valve Seat Contact Width
Valve Seat Correction
If the contact width of the valve seat is nearing the service limit, or
there are small depressions or wear on the valve seat, correct the valve
seat.
•
Using a 45 (30 only for the intake on FE350 and 400) valve seat
cutter, apply a light force to smoothly cut the valve seat to create a
concentric circle.
•
Using a 30 (15 only for the intake on FE350 and 400) valve seat
cutter, make a shallow cut so that the valve seat contact [A] will have
the standard width.