My 02 660 grizzly with 1300 miles will start and idle like new, as soon as I try to move it, the engine backfires so hard it blows the carb off of the engine, thank God for the throttle and choke cables, otherwise I'd be chasing the carb across the street all the time. What makes me feel like lean run, is that I can't really flood it out with the choke, It will run bad but not die. I can turn on the gas with the bowl off the carb and gas pours out from the needle and seat. If you put your hand over the intake and hit the starter it feels like it's going to suck your hand into the cylinder. Here what we've done: fresh gas, rebuilt carb, installed bigger jets, installed carb off another perfect running machine(I own 2), new plug, new coil, new plug cap(cracked $45!!), leak down test, adjusted valves, compression test(127psi), checked carb mount boot, 23kv at the plug while cranking. What am I missing, I would really like to ride this rather than look at it.