Did you adjust your idle with the idle screw? You might check for intake leaks. I think thats what I would try first. Welcome to the forum. Lots of motorized bicycle enthusiasts here..........................
Nothing sucks more than being in the middle of an argument and you realize you are wrong.........
welcome to the forum. whats with this cold weather we are getting? as bob said try adjusting the idle screw first. i have never heard of an bicycle engine kit being ready to run right out of the box and ussually need adjusting. glad to have you with us
First take the intake off and seal it with a good rtv sealant, than lower the carb clip a notch or two. If the engine is warm and you still can't idle it with the adjusting screw without having the choke on, try lowering the clip another notch. You want to try to run it a little richer on the air/fuel mixture. Small 2 strokes run hot when lean.
BTW- Check out other areas of these forums for other great info !!!
I learnt a pile from these guys who have been building them for awhile !!