I just put a new carb on my 77 Puch Maxi. The bike starts, and runs, but, when I start it, for example, with the kick stand down, the back wheel takes off! I mean, it is like I have the throttle all the way open, but it's not. If I pull the throttle, it goes even faster...too fast...like, my bike is going to blow up fast! Is this a idle problem? Is there a screw of something that I can turn to adjust this? Please help!