I had the same issues a while back... I had a 950 ProForm that uses the same venture size as the 850. I juggled shooter's, shooters with tubes, cams, and even a 50cc in the rear.
I finally went with a 750 HP I modified. I'm happy now, and I'd rather take a ball peen hammer to the forehead, than do that again !!
our motors are different.. mines a 360, yours a 408, so not a direct comparo, but nevertheless.
How much Ignition lead/total timing are you using? Open spacer, or 4 hole? Cam in the 240s @ .050 ?
