Racking my brain, which most will say takes a very small rack. I regulate a rather large irrigation ditch at an altiude of approx. 5000 ft. ele. and haul my workhorse to 8000 ft.,and ride from there to 9000 ft. to regulate 6 irrigation reservoir in the Big Horn mountains. Unloaded and headed across flat terrain noticing the old thang sounded loud, like an exhaust leak. As I started up the trail and asked for rpm’s, the respone was slow, and the more I asked from it the less it wanted to produce. Sputtering and back firing, I managed to get it back to a point where I could load it. Ok, enough said there. Back home, I found that fuel and air blew back out of the carb intake. My local guy, and if you get to Sheridan, WY look up Joe Hando, thought it might be the carb to motor connecting piece, NOPE, a new one and same results. Re-set the valve lash and that improved it enough that I thought I had it.NOPE, next morn, same thing. I take off the air box cover when at altitude, as this machine came from KS., and it has run fine for 5 yrs., thinking not that, gonna jet it though any way. Timing is dead on. Woodruf keys are intake. Just on the odd chance the muffler was plugging up, took it of and noticed low throttle to mid is good, sputters to high throttle, then screams like a banshi. I have no problem taking it to Joe, but I am one of those that figures the more I know the better off I am at the top of the mountain alone. Thanks in advance. JB:Thinkingof_: