stock compression

[redrider74]

does anybody know how many psi of compression a 2005 trx450r is supposed to put out?

[eastside 400]

if you still have the decomp on then it will be around 110 PSI. without the decomp it should be upwards of 200PSI

[redrider74]

It only put out about 40-50psi. I just replaced the crank in it. After I rode it for a little while I noticed oil pouring out of my crankcase vent. That's the only reason I tested it. It was rebuilt with new gaskets. My piston and rings are less then 10 hours old. What could be causing this low compression? Thanks

[muddzilla94]

maybe one of your rings broke, or it could be your decomp not adjusted right.

[eastside 400]

i would check the decomp and valve clearences, also, you need to kick atleast 5 times to get the 110 PSI. if oil is pouring out of your crank vent then i would think the rings are shot

[redrider74]

I put my stock piston back in and it's still pouring oil into the airbox. Valves and decompressioner are perfect. I have no idea what else it could be.

[muddzilla94]

is it overfull on oil? are your gaskets good it might be a leaky head or base gasket lettin antifreeze mix and over filling it. what color is the oil in your sight glass?

[redrider74]

Originally posted by muddzilla94
is it overfull on oil? are your gaskets good it might be a leaky head or base gasket lettin antifreeze mix and over filling it. what color is the oil in your sight glass?

not overfull. brand new gaskets. oil is the color it should be.

[eastside 400]

cracked piston possibly

[redrider74]

I've tried 2 pistons already. Both looked fine. I have heard that if the oil cooler has shavings in it there could be enough pressure built up to force oil out of the vent. I'm going to try that within a couple days.

[muddzilla94]

after i blew a head gasket mine smoked from the crank case breather a little bit for a couple hours then is quit, have u tried brand new rings or have they been used in your 450 before?

[redrider74]

Originally posted by muddzilla94
after i blew a head gasket mine smoked from the crank case breather a little bit for a couple hours then is quit, have u tried brand new rings or have they been used in your 450 before?

They have been used but both rings and both pistons are perfectly fine. The wiseco only has about 10 hours on it.

[muddzilla94]

i would buy brand new rings and try it then, hopefully that will fix it.

[redrider74]

Took the oil cooler off and lots of oil came out of the feed line but absolutely nothing dumped out of the return line. So is it even possible to clean an oil cooler or should I look for a new one?

[eastside 400]

you can try a flush kit, auto stores should have them for auto trans coolers, its an aeresol can that foams, ive tried it but it never really cleaned it out good. check ebay, plently on there usually

[redrider74]

Originally posted by eastside 400
you can try a flush kit, auto stores should have them for auto trans coolers, its an aeresol can that foams, ive tried it but it never really cleaned it out good. check ebay, plently on there usually

will do. but would I be alright riding saturday with the oil cooler bypassed? I know a lot of drag guys do it but would it be alright to normally ride with?

[doc-bones]

After a rebuild i had same problem oil draining into airbox and onto swingarm......
Problem was a 1" rip in center case gasket! It would pull oil from clutch side and up into airbox!

[redrider74]

well i bypassed the oil cooler and it's still pouring out oil. I'm about to give up. anybody have any more suggestions?

[killer454]

sounds to me like a lot of blowby in the cylinder,causing the compression to leak down in the crankcase causing the oil to blow out the vent.

sounds like the rings are bad or not seated,did you hone the cylinder when you replaced everything?

this would also account for the low compression if it is really bad on blowby in the cylinder.

i would buy new rings and rehone the cylinder this will most likly fix the problem.

this is just my opinion and what i would do if it where mine but other people might not agree and thats ok with me.