My buggy did the same thing....engine ran in reverse even though I KNOW! I had everything hooked up correctly. I couldnt give it throttle or it'd die instantly...but if I restarted it, let it idle for approx. 30 secs., there'd be a "jump" in the idle, and suddenly the wheels would RE!-reverse themselves....ie, turn correctly...some local guys told me that what probably was happening was it was very chilly, maybe 60ish. Given that, and a very rich setting, the engine might have been starting at BDC instead of TDC like it should. Seemed to make sense I guess...anyway, after it heated up a little, it was fine.I am also using a "hot" plug, which in effect, advances the engines timing. I probably could go with a "medium" plug, but I dint run very long cause it started raining
.....anyway...hope this helps you understand your problem....if it indeed was your problem as it was mine.