I have a 1985 Fourtrax that we bought new in 85. Used daily on farm for 20 years but now only used every month or so. I have noticed that when I crank the 4 wheeler it will idle and warm up but the more I drive it the hotter and faster it revs to the point that when you shift gears it wants to pop up so I have to cut it off and let it cool down and then it’s OK. The motor gets so hot it will burn your leg on the muffler side of the engine. Could this be a carb. problem? We have never re-built or changed anything on the 4 wheeler other than standard maintenance items like oil, grease, battery, filter, plug. Thanks.