mine is stumbling right at 6500 also but not backfiring, wont rev past that point.
I cant find anythingwrong fule pressure is good and doesn't drop, it doesn't appear to be a fueling issue as it starts dumping fuel (black smoke) if you give it more throttle.
its like a limiter is on.
two things I have heard....one its the hood wiring harness right at the hood hinge point. it breaks a wire and causes the issue , the other is that the wiring harness on the sled has isses and fails causing the problem, most likely a ground connection faulty. one more thing I have heard is the oil tank sending unit wiring causes all sorts of odd problems.
so
unplug the main harness behind the pipe, that eliminates everything on the bars being the issue. - try / reconnect
unplug the oil tank sending unit - try / reconnect
unplug the hood harness - try / reconnect
look everywhere at the grounds and make sure your getting contact
something to check not related to the problem is the calibration of the TPS on the side of the throttle bodies. I checked 6 sleds and 4 of them were out. I think it is part of the issue of me losing three piston/cylinders on my m1000. my 08 m8 was out of spec when I checked it.
good luck and please post the fix!
spomey
