2012 Sportsman 400/500 and EFI Tractor Service Manual 9923412, Page 33Get this manual
MAINTENANCE Fuel Lines
1Check fuel lines for signs of wear, deterioration, damage, or leakageReplace if necessary2Be sure fuel lines are routed properly, the connectors latched and the lines secured with cable ties
Compression Test
NOTE: 500 and 455 4-Stroke engines are equipped with an automatic decompressorCompression readings will vary in proportion to cranking speed during the testAverage compression (measured) is about 60-90 psi during compression testSmooth idle generally indicates good compressionLow engine compression is rarely factor in running condition problems above idle speedAbnormally high compression can be caused by decompressor malfunction, or worn or damaged exhaust cam lobesInspect camshaft and automatic decompression mechanism if compression is abnormally highA cylinder leakage test is the best indication of engine condition on models with automatic decompressionFollow manufacturer's instructions to perform cylinder leakage test(Never use high pressure leakage testers as crankshaft seals may dislodge and leak)Cylinder Compression Standard 60-90 PSI Cylinder Leakage Service Limit: 10 (Inspect for cause if leakage exceeds 10)