Originally Posted by
satoch
I just switched to Byron's 20% Gen2 from Byron's 30% Original on my 3 port Race that had about 1 gallon on it.
It still has a very good pinch but is broken in. I had a hell of a time getting a tune today.
I finally had to remove a .109mm shim. That helped a lot but it still seems to lean bog on the low end and doesn't have the proper snap. Suggestions?
Try a different plug perhaps. Not sure what your currently using but OS P3 or P4 seem to work very well on these motors.
I would go back to 25% or 30% fuel and original shimming. I believe the Go motors like a healthy dose of nitro and a hot plug.