I have a trx400 that heats up a ton in the top end. So much so that the old seat melted on the front. Only the top end gets that hot. The oil goes black quickly and the vent on the bottom end is constantly blowing out something that I think is burned oil exhaust. I have a strong feeling that my rings are shot. Also the fan doesn't ever turn on nor the overheat light, besides right when I turn the key on. I thought I had better talk with the more experienced men first. Thank you for your input.