Time for a leak down tester. Even with torqueing to specified settings, I sometimes find that somethings just are not sitting properly, and I lose pressure over three or four minutes.

Something to also do, is use a very lite amount of assembly grease (I use the red Silkolene stuff) on the base gasket. When I say lite, I really mean lite. Basically just a little on my finger, and put a VERY LITE film on the two faces of the gasket. This helps in a couple ways. Helps create a better seal, as well as helps with the base gasket not sticking to the case, or the barrel.

Now you need to remember that leak means air is getting in. This means that you are technically leaning out the mixture in the cylinder. That and your compression will be off.

Damn two strokes... if they were only as easy to tune as a four stroke!
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Charles Gallant