Testing Engine Compression; Spark Plug; Muffler/Spark Arrester - Arctic Cat DVX 400 2008 Service Manual

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Testing Engine
Compression
To test engine compression, use the following proce-
dure.
1. Remove the high tension lead from the spark plug.
2. Using compressed air, blow any debris from
around the spark plug.
! WARNING
Always wear safety glasses when using compressed
air.
3. Remove the spark plug; then attach the high ten-
sion lead to the plug and ground the plug on the
cylinder head well away from the spark plug hole.
4. Attach the Compression Gauge (p/n 0444-096).
NOTE: The engine must be warm and the bat-
tery must be fully charged for this test.
5. While holding the throttle lever in the full-open
position, crank the engine over with the electric
starter until the gauge shows a peak reading (five
to 10 compression strokes). The compression
should be 10.0 kg/cm
6. If compression is abnormally low, inspect the
following items.
A. Verify starter cranks engine over at normal
cranking speed.
B. Gauge is functioning properly.
C. Throttle lever in the full-open position.
D. Valve/tappet clearance correct.
E. Valve bent or burned.
F. Valve seat burned.
NOTE: To service valves, see Section 3.
7. Pour 29.5 ml (1 fl oz) of oil into the spark plug
hole, reattach the gauge, and retest compression.
8. If compression is now evident, service the piston
rings (see Section 3).
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(142 psi).
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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.
! CAUTION
Before removing the spark plug, be sure to clean the
area around the spark plug. Dirt could enter engine
when removing or installing the spark plug.
Adjust the gap to 0.7-0.8 mm (0.028-0.032 in.). Use a
feeler gauge to check the gap.
When installing the spark plug, tighten to specifica-
tions (see Section 10).

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.
! WARNING
Wait until the muffler cools to avoid burns.
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