I have an aftermarket exhaust, uni air filter, and speedo....back when I had the stock balloon tires on mine, I got it up to around 52...it was still climbing but I was running out of road, I'm sure it would have hit 55-57 though. I have a friend with a Yamaha big bear 400 4X4 that I have beaten several times in a drag race and when I got the Red up to 52 that time, he couldn't catch up with me to save his life...
1985 Yamaha 225DRN w/OEM headlight guard, footboards, front rack, rear rack, work light, brush guards and trailer hitch