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Ok, i'm about a week or so away from buttoning up the rebuild on my 92 LT250R. Iwant to do a leak down test before I fire it up, but would like to go over a few things, since ive never done it before. I've seen a few videos on youtube, and read a few articles. I plan on using the harborfreight leak down tester, any thoughts on this? Ive seen how alot of you make your own, but really dont want to go that route. I plan on using soapy water to detect any leaks as well. What PSI would you guys recommend during the test? What all exactlly must be plugged up? What would be a good indication that the cylinder is within spec (leak %, time it takes to leak down, etc.)? Any other tips, things to look out for, warnings, or other advice? Even though I have searched around a bit, i've only seen just photos of a few being done in a few build threads, but I was kind of vague on it. I'm considering doing a video, maybe for this site, so doing it properly, and having all of my bases covered would be best.

On another note, what are the specs for compression after a fresh cylinder bore/hone/new piston kit? (will be doing a compression test as well).

Thanks
 

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I think you may confusing a cylinder leak down test with a crank case pressure test that is used to check for air leaks on a two stroke engine. A cylinder leak down test shows how much compresion is lost in a given amount of time. A leak down test on a two stroke is pressurizing the crank case and seeing if it will hold air pressure for a given amount of time to check for air leaks that will lead to a lean condition. The exhaust must be plugged and a plug with an air fitting and a low pressure air gauge mounted in it. Your motor should be able to hold 5 psi for 10 minutes. If you suspect a leak spray soapy water around the seals and the base gasket and look for bubbles:thumbsup:
 

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There is no set number of where your compression should be, it will change with the thickness of the gaskets, milled head, etc. You more or less just want to get a baseline so you can keep tabs on it. You'll probably be somewhere around 190psi.

We just covered the leak test pretty good in this thread: http://forums.everything2stroke.com/threads/49954-Carb-issues-rough-idle You need a tester with a low pressure gauge, the one you have is probably too high, 15-30lbs max is what you want. You could probably do it that way if you replaced the gauge but by the time you get the gauge and something to plug off the intake and exhaust you might as well just build your own tester, it only takes a few minutes once you have everything.

I just took my intake into Lowes with me and found a piece of pipe that fit snug into it that I could cap. Where you at in PA?
 

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Make your own. Pressure is low enough that you can use hose/tube and hose clamps. We're talking 5-7psi...from a hand pump. Hardest part is finding a low pressure gage. I used a mechanical boost gage.
 
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