2-5
2
NOTE: The compression should be within a
range of 200-215 psi (250 Utility) or 210-230 psi
(DVX 300) in the full-open throttle position.
6. If compression is abnormally low, verify the fol-
lowing items.
A. Starter cranks engine over.
B. Gauge functions properly.
C. Throttle lever in the full-open position.
D. Valve/tappet clearance correct.
E. Valve not bent or discolored.
F. Valve seat not discolored.
NOTE: To service valves, see Section 3.
7. Pour 29.5 ml (1 fl oz) of oil into the spark plug
hole, attach the gauge, and test compression.
8. If compression is now evident, service the piston
rings (see Section 3).
Spark Plug
A light brown insulator indicates that the plug is cor-
rect. A white or dark insulator indicates that the engine
may need to be serviced or the carburetor may need to
be adjusted. To maintain a hot, strong spark, keep the
plug free of carbon.
ATV-0051
Adjust the gap to 0.8-0.9 mm (0.032-0.036 in.) for
proper ignition. Use a wire feeler gauge to check the
gap.
ATV0052B
When installing the spark plug, make sure to tighten it
securely. A new spark plug should be tightened 1/2
turn once the washer contacts the cylinder head. A
used spark plug should be tightened 1/8-1/4 turn once
the washer contacts the cylinder head.
Muffler/Spark Arrester
The muffler has a spark arrester which must be period-
ically cleaned. At the intervals shown in the Periodic
Maintenance Chart, clean the spark arrester using the
following procedure.
1. Remove the cap screw (1) securing the spark
arrester (2) to the muffler assembly; then carefully
remove the spark arrester.
KM139A
2. Using a soft wire brush, clean the carbon from the
screen (3) taking care not to tear or damage the
screen.
! CAUTION
Before removing the spark plug, make sure to clean
the area around the spark plug. Dirt could enter
engine when removing or installing the spark plug.
! WARNING
Wait until the muffler cools to avoid burns.
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Summary of Contents for ATV 250 Utility 2009
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