does this sound like an air leak I can adjust the low end any way and realy no change I can bring the idle down and it will idle fine for a few seconds and the rpm drops and it dies I can adjust the low end needle in all the way and the engine still runs at idle and the rpm drops also when i throtdle up the carbs loads up and dies my other avistar runs fine the low end is adjusted out about 3/4 turns ive checked the fuel line and the tank so what do you all think michael

There was along thread about this a while ago, many of the Aviastars had bad carbs. It`s a warranty case, get it replaced by a good one

i managed to shim a carb from a trashed 55ax, and sealed it on with Ultra Copper gasket maker, and it runs great... the engines are pretty much useless if you dont have a good carb on it. i ordered mine a few months ago well after the problem was acknowledged and still got a lemon carb

I had 4 of these little jewels. One threw a rod, I bought a pair of Supertigre carbs for two, and I ended up modifying the carb on the last one. The two with the Supertigre carbs ran ok, and the one with the modified carb ended up running ok too......good engines....junk carbs....but that was my experience. I understand that some of these engines have given no trouble at all. I was just unlucky.....4 times[]

Dismantle the carb and be sure to expand (very little) all o rings in it.You can begin with H.S.N. and also L.S.N. o rings.The problem is some o rings are not sealing properly.

checked the o-rings and checked the carb for dirt and I just applied some rtv to the carb base and reinstallled the card making sure that i was holding the carb down tight michael

If it doesnt fix the problem please call bob Nelson at Sig and exchange it for a good carb.

I will do that thanks michael