Re: Fourstroking @ WOT... help.
Try running without your gas cap once. A few of them don't vent right from the factory (including mine). A smaller jet may be in order. You may want to do a plug chop to check jetting. I needed a smaller jet after break-in.
Also, if you have a stock engine, are you sure you're doing 28-29mph? That's about as high as I would want to rev it with a 44t sprocket. When I first got my speedo, I set it for the stock 26" wheel size, but it was too fast by about 3mph according to gps. I had to measure the circumference and enter that into my speedometer.