Suzuki 2 Strokes

I discovered a rather annoying problem on a recent road trip with the GT750, when shifting down from fourth to third to pas a car it suddenly dropped down to second . Usually it happened when I had accelerated quite a bit so the revs went to the roof...
Any ideas what can cause it? I thought worn dogs on the gears would lead to false neutrals and not jumping between gears.

Sorry to hear this..worn dogs,selector problems for sure...changes up or down should make lttle difference,third gear can cop a lot of work,usually one of the first gears in the box to give you trouble after years of hard work.As you probably know you have to replace gears as a set,third gear driven,was the one that wore out in my "A" model.The gearbox wasn't giving me trouble at the time,BUT the motor was,found the gear problem when it was apart!
Regards,
GT750Battleship.

So after nearly 7 years i took the time to split the cases and found the dogs on the 3rd driven to be severely rounded off. Surprisingly the 4th driven which it mates with looks ok.