Generac Power Systems 53187 - Manual (Page 72)

PART 2
ENGINE MECHANICAL
I
SECTION 2.4
DISASSEMBLY AND INSPECTION
VALVE SEAT (CONTO):
Cylinder Head Assembly (Continued)
Valve seat contact width
Standard width
1.2 to 1.5 mm
Allowable limit
2.0 mm
Figure 11. Grinding the Valve Seat
Figure 9. Correcting the Valve Seat
VALVE RECESS:
If the valve recess (Figure 10) exceeds allow able
lim its, replace the valve seat.
Recess of Valve Seat
Standard Recess 0.033-0.045 inch
(0.85-1.15mm)
Allowable Limit 0.071 inch (1.8mm)
Recess
Standard
value
Allowable
limit
Squareness (mm) 1.2 2.0
Free length (mm) 35 33.5
Spring force 130.4mm
at compressioned) (kg)
8.1 7
Squareness
Free len
Figure 12. Valve Springs Inspection
CAP AND INSERT:
Rem ove CAP and INSERT from the cylinder. In­
spect and clean the com bustion cham ber.
Figure 10. Checking Recess of Valve Seat
GRINDING VALVE SEAT;
See Figure 11. Use a valve seat grinder and valve
grinding com pound to grind valve seats. Check the
valve contact face for correct contact and positioning.
NO TE: W hen Installing a new cylinder head, use the
valve seat cutter to obtain correct seat contact w ith
recess of seat. T hen, use lapping com pound to lap
the valve In.
VALVE SPRINGS:
Inspect valve springs for dam age. Check spring
squareness. Use a spring force tester to test for cor-
rectspring force and free length.
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