2
9926806 R03 - 2015 - 2016 RANGER ETX / 570 2-SEAT 2015 - 2016 RANGER 570 CREW Service Manual
© Copyright Polaris Industries Inc.
2.19
ENGINE COMMON
COMPRESSION AND LEAKDOWN TEST
NOTE
This Polaris 4-Stroke engine is equipped with an
automatic decompressor. Compression readings will
vary in proportion to cranking speed during the test.
Average compression (measured) is about 80-120 psi
during a compression test.
Smooth idle generally indicates good compression. Low
engine compression is rarely a factor in running condition
problems above idle speed. Abnormally high
compression can be caused by a decompressor
malfunction, or worn or damaged exhaust cam lobes.
Inspect camshaft and automatic decompression
mechanism if compression is abnormally high.
A cylinder leakage test is the best indication of engine
condition on models with automatic decompression.
Follow manufacturer’s instructions to perform a cylinder
leakage test (never use high pressure leakage testers as
crankshaft seals may dislodge and leak).
Cylinder Compression
80 - 120 PSI
Cylinder Leakage
Service Limit: 10%
Inspect for cause if leakage exceeds 10%
MAINTENANCE
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