Generac Power Systems GN190H, Руководство по обслуживанию и ремонту

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SECTION 9: VALVE TRAIN
33
TO PREVENT EYE INJURY, ALWAYS WEAR EYE PRO-
TECTION WHEN REMOVING VALVE SPRINGS.
5. Support the valves with your fingers while compressing the valve
springs with your thumbs on the valve spring retainer (see Figure 9.5).
a. With the spring compressed, slide the larger hole of the valve
spring retainer toward the valve stem.
b. When the larger retainer hole is around the valve stem, release
the valve spring.
c. Remove the retainer, spring and washer.
Figure 9.5 — Compressing Valve Springs
6. Remove the intake and exhaust valves.
7. Clean all parts.
a. Remove carbon from the valve heads and stems.
b. Inspect valves and valve seats.
c. Service parts as outlined under “Valve Service.”
VALVE SERVICE
VALVE:
Replace valves if they are
damaged, distorted or if
the the margin is ground
to less than 0.039 inch
(1mm).
If valves are in usable con-
dition, grind or cut the valve
faces to a 45º angle (see
Figure 9.6).
Figure 9.6
VALVE SEATS:
Valve seats are not replace-
able. If they are burned or
pitted, they can be
reground using a grinding
stone or Neway Valve
Reseater. Grind seats at a
46º angle and to a width of
0.039 inch (1 mm) (see
Figure 9.7).
Figure 9.7
The recommended procedure for cutting a valve is to use
the “Neway Valve Cutting System.” This type of system uses
cutters of three different degrees.
First, use the 60º cutter to clean and narrow the seat from
the bottom toward the center (see Figure 9.8).
Second, use a 31º cutter to clean and narrow the seat from
the top to the center.
Finally, use a 46º cutter to cut in the seat to a width
of 0.039 inch (1mm).
Figure 9.8 — Cutting a Valve Seat
60º
15º
BOTTOM
NARROWING
TOP
NARROWING
TOP
NARROW
BOTTOM
NARROW
BOTTOM
NARROWING
CUTTER
SEAT
31º
46º
31º
46º
TOP
NARROWING
CUTTER
SEA
T
SEA
T = 0.
039 i
nch
SEAT
CUTTER
SEAT
WIDTH
46”
FACE
45º
STEM
MARGIN