How are you riding.......fast or slow? Be aware that if you ride around slow in first or second gear a lot or even let it sit and idle for a while, the engine will heat up. You will be able to feel the heat from the engine on your legs. Or do you think it's getting a lot hotter than that?
Most 4-wheeler problems are caused by a loose nut connecting the handlebars and the seat!!
You only need two tools in life -- WD-40 and duct tape. If it doesn't move and should, use the WD-40. If it shouldn't move and does, use the duct tape.