Leak Down test

[arakyle]

What do you guys do to perform a leakdown test? I'm new to 2 stroke engines.... had quite a few 4s.... just want to keep my R healthy.

[Aceman]

http://www.duncanracing.com/techfaq/Tech_2-stroke-pressure-testing.phtml

[arakyle]

Perfect. Thanks!

[GPracer2500]

FWIW, I was able to find everything I needed to make a leakdown tester from Home Dept for like $20. Works fine and way better for me then spending big bucks for a commercial unit.

http://i34.photobucket.com/albums/d133/gpracer2500/PB160036.jpg

[arakyle]

What do you use to block off the exhaust or intake? That setup is what I'm going to use as well. Did you find the gage at Home Depot as well?

[GPracer2500]

Yes, the gauge is from HD. Took some searching to find it. The clerks were no help. If memory serves, it was in a small section of natural gas fittings/hoses. It was NOT with all the other brass pipe fittings or with the air compressor stuff. The gauge and all the brass pieces shown came as a unit for $12 I think. The rest is just PVC fittings. Take your carb boot with you. I guessed at the right size PVC piece and overestimated the size I needed.

I blocked off the exhaust using the the exhaust flange and a piece of rubber from an old motorcycle inner tube. I just bolted the flange onto the cylinder with a doubled over section of rubber captured between the flange and the cylinder. Under pressure it bulged out more than I was expecting but was air-tight. I also made a simple metal plate backed with inner tube material that I was going to use. I ended up not using it because just using the flange was a bit easier. Some people use expanding rubber plugs but I couldn't easily find the right size.

Be sure to spray soapy water everywhere (including where the gauge threads into the brass piece--mine leaked a bit and needed to be resealed after I had rotated the gauge for better viewing). Even the tiniest leak should bubble up. You don't want to chase down a leak in the engine that's not there when it's the tester itself that has the leak.

[arakyle]

Thanks for the info. I'm going to duplicate your set up... looks great... and a ton less expensive than the leak down equiptment. Thanks again!

[gandgracing]

I always do a leak check if the topend comes off. The biggest problem area I have seen is the reed gaskets.

[Aceman]

Originally posted by GPracer2500
Some people use expanding rubber plugs but I couldn't easily find the right size.

I found my expanding plug at Ace Hardware. It was in one of those pullout drawers in the bolt/nut/screw aisle. It's been a while, but I believe it was an 1 1/2" or 1 5/8" plug.

[jon370r]

Better yet. To block off the exhaust look for the rubber PVC end caps that just tighten on with a hose clamp (included for $3). It will slip right over the exhaust flange with out removing it and it works great.