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2015 800 Pro Rmk Compression?

ryan6308t

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Dec 7, 2007
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Minnesota
Sorry, I am sure this has been asked a lot....did a quick search on the forums here and came up with ~120-125 psi. Is this the correct number and what is the proper way to check? Both spark plugs out and motor cold? Other?

2100' elevation

Thx, Ryan
 

sledhed

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Dec 19, 2001
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Lolo, Montana
Also depends on your gauge... I made the mistake of buying a Harbor Freight with the quick disconnect... I tested it with the compressor and the number it gives is accurate that way, but the sled and motorcycle I tested it with don't pump it up very high, I believe due to the added volume... someone can correct me if I am wrong (and if so the sled and motorcycle need an overhaul)... :)
 
V

volcano buster

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Nov 26, 2007
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Stayton Oregon
Assuming the gauge is good:

Pull both plugs and turn the key off (or kill switch or both)
Install gauge in one hole
Hold throttle wide open while pulling
Take note of pressure, purge and repeat
Install gauge in other hole
Hold throttle wide open while pulling
Take note of pressure, purge and repeat

I then add some 2-stroke oil down the plug hole, enough to more than wet the top of the piston so it will wick down and lube the rings. Pull the motor over several times to get oil distributed.

Repeat above steps.
Compare any differences in compression which should give you an indication of how much loss you could be getting by the rings.

You are also interested in both cylinders being similar in compression.
 
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