I have a new ys 120 on my pro edge,since installing the engine it seems it has never ran correctly,now if i go above say 1/4 throttle it stalls,ive gone threw just about every adjustment scenario i can think of,does anyone have any ys knowledge they could lend?I used a 16-4w prop so not to cause over reving,i ran the motor rich,ive canged the plug numerous times.What have i done wrong?Is the bottom end messed up?Thanks.