Arghh chain problems!

[aerlinfall]

I have a grubee skyhawk 66cc mounted on a trek 830 mb. My issue is with the chain, Im currently using a #41 chain because my 415 bmx chain kept breaking. On my 41 chain i took some links off to better fit around both sprokets, when i go out to ride itll pop off the rear sproket. I know the chain has ALOT of slack but when i go to remove a link then the chain ends up being too tight. Ive tried the chain tensioner but the #41 is too big to sit comfotably in the wheel. Im so frustrated i dont know what to do anymore.

 

[JonnyR]

your alignment must be off to break a 415 bmx chain and to fix the tension issue you need to shim the rear mount away from the seat tube to take the slack out