Air leak!..

[muhuha]

Ive got a air leak in my bike after doing a crank rebuild, i think ive identified it to be the crank seals because the 1st one (vario side) i put in was bent :7 so i tried my old one with silicon gasket and this basically solved the problem. I didnt let the silicon set and its gone back to what it was like before. Ive bought new seals when i put them in do it put them in dry, greased or with instant gasket thinly spread over the inside and outside?

Also how can i tell if my crank halves have a leak, when running ive sprayed oil over them and no bubbling..

 

[manny]

Im not sure if this will work on 2 stroke but while running if you spray the area that leaks the idle rpm should change

 

[narx]

It's impossible to be sure that engine is air tight without performing a pressure test, especialy when minor leaks are concerned.

It's easy to make a testing device:

http://atv.off-road.com/atv/article/articleDetail.jsp?id=190479

For oil seals, sealant is not necessary, just grease an inner surface.

 

[Mexicano]

A "Home Made" Air Leak Tester

Very easy to do...and cheap...a great tool, this is mine, with 3 different couplings for carb sizes:

 

[Rage]

Very easy to do...and cheap...a great tool, this is mine, with 3 different couplings for carb sizes:

That's what I use8) .

Muhahuhuahua, if you bent the seals when you put them in then you should have ripped them out and put new ones in.
As for silicone!! Sillycunt..They go in dry, carefully push them in with your thumbs - not too far either and with no gasket goo. Just a little 2 stroke oil on the crankshaft to help the seal lip slide over the crank.

 

[muhuha]

i know just got a bit late and i left it, anywho i installed new seals with a thin gasket let it set for a few hours and BINGO.

 

[manny]

I think you can also use vacum to check instead of presure I have one of those hand pumps for bleading brakes and I remember reading something about checking 2 strokes for air leaks on the instructions

 

[animojog]

you can use a compression test check hose attach to airhose, and turn down the air regulator. to hear air leak hissing noise

 

[Anotherugly70cc]

good idea

Great! I was looking for something like this! I just bought a 2 stroke scooter manual and it has zip on checking this!

 

[Zumaman]

When you install your seals, use a large socket that fits alont the rim of the seal. Tap it LIGHTLY until it is in place. If you dont use a socket and just tap arround the edges, it will bend. Also, make sure you dont tap it too far or it will rub on the bearing, causing wear. This will result in leaks over time.