yeah, no carby for me, but i suspect somehow i have an exhaust leak, hmmmmmmm. i dunno, when i retarded the timing (twisted dizzy anti-clockwise) it stopped doing it, advancing it made it worse, but i've had it timed properly and its still going, dammit... i just haven't had time to sit down properly and work thru some stuff, altho i'm pretty sure its not the throttle body as i changed that a few weeks ago