Leak down testing the LT250R engine

[nevrserious]

I just did a top end rebuild and have approx. 6-8 hours on it. The bike ran normal for the first 5-6 hours of break in but in the last hour or two of ride time the idle started to stay a bit high for a few seconds before dropping to normal. I tried the ether test to check for air leaks and found nothing. The bike is still smoking more than it did before the rebuild so I was told it could be a bad right cranksharft seal, or maybe it's just not broken in fully. Something is up though for the idle to be acting up so I would like to pressure test the engine to check. However I've read different opinions about testing the Suzuki engine due to the power valve. Anyone, anyone, Bueller, Bueller...

[Banshee]

Sounds more likes a possible throttle cable getting stuck possible. I have never done anything different on a pressure test on my LT

[nevrserious]

Something about the o-rings on the power valve will leak air past them so need to block the tranny breather tube to pressurize the whole engine. But if the o-rings leak air past them they should be replaced right? Or would it be normal?

[Banshee]

I have never had leaks past the o-rings so i would have to say you need to rebuild your powervalve

[nevrserious]

Sounds good, now I know. I haven't performed the test yet but wanted to get the facts straight before I do so. Also the only 2 stroke leak down tester I can find is no less than $220 made by Motion Pro. I found an article on how to build my own so I guess I'll go that route. Any thoughts however would be appreciated.

[RichM1983]

I could be wrong but dont you have to do a leak down with the piston at top dead center and since the piston is at top dead center the powervalve wouldnt matter. I mean if you did a leak down test the the piston in a postion where the powervalve would effect the leak down then wouldnt the air just blow out of the intake or the exhaust? Im pretty sure you dont have to worry about the powervalve.

[sblt500r]

Originally Posted by RichM1983

I could be wrong but dont you have to do a leak down with the piston at top dead center and since the piston is at top dead center the powervalve wouldnt matter. I mean if you did a leak down test the the piston in a postion where the powervalve would effect the leak down then wouldnt the air just blow out of the intake or the exhaust? Im pretty sure you dont have to worry about the powervalve.

you do a leak down test to check for leaking around the base gasket, crank seals, intake and exhaust manifold. you have to worry about the powervalve because you plug the intake and exhaust holes, and if you have leaky o-rings around the powervalve they will leak and give a bad reading. it doesn't really matter if they leak when the bike is running, because the exhaust gases just flow by it, and theres no suction like on the other parts of the engine.