Re: 90cc 2 strke cyclinder and piston kit?
Boring out the cylinder on its own isn't going to give you enough power to hit 80, and even if it did, the rest of the engine components are not built to handle that speed. Like the other guy said, your crank is going to give out before you get close to 80. The rpms required to allow an ht engine to hit 80mph would very likely cause the engine to experience multiple mchanical failures in a very short period of time. I am sure that there are engines that can allow a bicycle to achieve speeds of 80(+)mph without causing damage to the engine or bicycle frame, if the proper frame is used.but an ht engine is not it.