When I was a young boy I was coming home on my AT1, just about stalled it as i stopped at the traffic lights but managed to whip in the clutch lever and saved the situation. The bike sat there and idle for the 2-3 minutes but when I went to do the normal 'drag bike like' 125 take off the bike moved backwards
, at a good rate of knots
. Again I whipped the clutch in without damaged to me, the bike or the car behind. I sat there in disbelief as I tried the clutch 3 or 4 more times - same result. Eventually turned it off and kick started the beast without a prob.
Two strokes, especially those of mild tune that fire near TDC, run happily in both directions. I believe BSA Bantams were particular proned to it - they would just hestiate while idleing and end up running backwards.