help on Leak down test

5 replies to this topic
  • Guest_Guest_*

Posted January 16, 2001 - 02:09 PM


I wrote earlier about my bike suddenly having no power. I went back and looked at the compression. I was able to kick start my bike with out the compression release.So I checked to see if it was hanging up, it wasn't. I figure I would try a leak down test,but I'm not exactly sure if I have done it correctly or not. I put the piston at TDC on compression stroke, and then pressurised the cylinder to 40psi. It would not hold air . It was escaping through one of the exhaust vavles, I'm not sure how to check to see if was leaking past the intake vavles or not, I figured I should stop there for now. Any Ideas on what I should do next would be gladly appreciated......Thanks

  • Boit

Posted January 16, 2001 - 04:30 PM


Suppose you remove the airbox and with the throttle held wide open, you listen for air escaping thru the intake?

  • F-Pilot

Posted January 16, 2001 - 07:09 PM


Crazy, didn't you just adjust your valves? I would pull the valve cover and check the clearances.

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  • Guest_Guest_*

Posted January 16, 2001 - 08:09 PM


F-Pilot, yeah I just did the vavles. I thought something might have gone wrong with them, just like you said, but they were still in the same specs, as when I left them in. The bike ran good up and down the street. when I got it out to the desert, it didn't even have enough power to get the front tire up in first.It has a slight exhaust vavle leak but I don't know if that would be the problem or not. I marked the chain and the cams like was mentioned in this forum before so I know the cams are fine. Any other invo would be grateful.......Thanks

  • teamtoxic

Posted January 17, 2001 - 04:46 AM


Crazy, I posted a message about finding air leaks a few weeks ago. Here it is......

I recently discovered the easiest way to find air leaks on a bike, snowmobile, anything with angine; with a set of torches just turn on the oxygen and wave it around all the gaskets top to bottom. If there is an air leak the engine RPM will increase.

Just make sure you ONLY turn on the oxygen and not the acetylene unless you're on a suicide mission.

Hope this helps you out. I almost cried when I discovered how much time and aggrevation this saves.

  • Guest_Guest_*

Posted January 17, 2001 - 05:00 AM


Im not sure this is what your talking about, but another way to test for intake leaks, if you dont have torches, is with carb cleaner. Just be ready to put any flames out. It will do the same thing. Spray it on around any possible leaks and if there is a leak your idle will pick up. I thibk you are actually talking about compression leaks, which in that case I cant offer you any advice.
I lied. Actually something similar happened to my 400. I think it had something do do with the compression release. In my situation, before I had a chance to do anything it fixed its self.


[This message has been edited by npuza (edited 01-17-2001).]

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