The thick plottens. I pulled the carbs and one had a big chunk of black rubber in the float bowl. So I pulled the emulsion tubes, mains, slow jet, floats and blew out everything. Now it idles great and seems to WANT to take throttle but still backfires. Better. I guess I'll pull a set of carbs and throw them on (from a street bike) and see what happens. ARggh Ernie