I'm pretty new to this, but I'm having a problem with my back tire wanting to lock up when I push the clutch handle in. Here's a little background on what I have. A flaming horse silver slant 80cc motor. Mounted on a specialized bicycle. One of the older specialized bikes (about 15 years). Standard 26 inch tires and rims. I ride everyday to school, so I really need some help with this please. Oh my clutch is a brake/clutch combo handle.