old motorbike New Member Sep 21, 2008 352 1 0 74 Fl. Sep 28, 2008 #1 Today I had the idea to run my GPS on the motorbike just for speed checking. After a few blocks, it ran a top speed of.........28.2mph!!!??? WOW, and that was tucked in. I have a 36t sprocket ordered to see what that will do stock.