Thread: GP1300r compression test
10-03-2009, 07:40 PM #1
GP1300r compression test
I'm buying a gp1300r and would like to know the correct procedure for doing a compression test on this particular boat. Is there anything special you have to do, like giving it full throttle?
10-03-2009, 09:33 PM #2
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10-03-2009, 10:24 PM #3
If every cylinder is above 110 psi then its in good shape, and they should all be right around that, if one is 10psi or lower then it has a one way ticket to needing a rebuild. A compression test is easy, just pop out the spark plugs, hold the throttle open, and hit the starter until the gauge will not move anymore and there you have the compression of that cylinder.
10-03-2009, 10:26 PM #4
10-03-2009, 10:47 PM #5
One other variable i didnt see listed....
Some (economical) compression testers will have the shrader valve at the gauge end of the hose.. These will read lower compression numbers because of the added volume the hose allows.
To read correct cylinder compression the shrader valve needs to be on the cylinder head end of the hose, which will eliminate added CCs from the volume of the hose, which can be 10-15 pounds or more, depending on the length of the hose.
On a hose with a shrader valve at the gauge end of the hose, the longer the hose, the lower the compression.
Check your gauge and hose, and find the shrader valve, so you know what you have.
Not to be confused with the gauge pressure release valve usually mounted on the gauge itself.
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