2004 Polaris Virage low compression refers to when cylinder compression falls below 100 psi per cylinder. A cylinder will typically fail to fire when compression falls below 90 pounds.
A 2004 Polaris Viarge with a low compression reading in one cylinder will misfire and cause the watercraft to run rough, low compression in all cylinders will cause the engine not to start.
The following repair information identifies possible causes of low compression. Check for one or more possible malfunctions:
- Cylinder damaged, worn or improperly bored or honed.
- Choke throttle closed (both must be wide open when performing a compression test).
- Piston damage (refer to piston damage in download repair manual for more information).
- Head gasket failure or loose cylinder head.
- Piston rings broken or stuck, or excessive end gap.
Performing a cylinder compression test will indicate the engine’s overall condition provided a high quality compression gauge is used for testing and the battery is fully charged.
Before performing a compression test, ensure the spark plug high tension lead is securely grounded to the jet-ski’s engine block and attach spark plug wires to grounding posts.
- Remove each spark plug high tension lead and securely connect each one to grounding posts.
- Remove each spark plug and insert the compression gauge into the cylinder you intend to test.
- Using the starter motor, turn the engine over with throttle plates wide open until a maximum reading is obtained on the compression gauge (roughly 3 to 5 seconds of cranking). Then record the compression reading.
- Repeat steps 2 and 3 for the remaining cylinder(s) and compare to each other cylinder. All cylinder reading must be within 5% of each other.
Compression (open throttle at sea level):
- Standard – 120-150 lbs./sq. in 8.40-10.5 kg/sq. cm
- Service limit – greater than 5% variance between cylinders