450r buying help? comp. psi?

[Murph393]

alright, going to pick up a 05 trx450r i found for 2500 obo, giving the guy 2300...it needs valve adjustments, rear srocket and bearings...thats all, needs some other work but thats it for now...ill have some extra money for it...

my question was to him is the compression and if he would take it...what should it be around? im very intewrested in it mostly because the price...but im probably taking it home.


thanks. i just dont want to get a piece of junk.

[GPracer2500]

108psi is the standard spec. However, that figure is dependent on how the auto-decompression device is set. That's why 108psi seems like such a low number for a healthy engine; the auto-decomp releases a bunch of pressure at cranking speeds. Assuming the auto-decomp is set correctly, a comp check can give you some information about how well the cylinder is sealing. But comp test results can be particularly hard to interpret when there's an auto-decomp device at play--especially when the device can be adjusted to release more or less pressure like on the 450r.

A leak down test would be the preferred (although more involved) test.

[Murph393]

so i should be looking foraround 90-110 psi?