Hi everyone ! A while back I acquired a 80 6x6 with a 16 hp Techumsi that was suppose to have been rebuilt by previous owner. The motor runs but it seems to vibrate badly like its out of balance. Is this normal for these motors? or is there something wrong with it. It's hard to start it fires right away but will not idle. I figured that is a carb issue. When you rev it the whole machine vibrates. Any suggestions would be appreciated.