It's 4:38am and I can't sleep. Yesterday was the same so I decided to tear down my spare motor and count gear teeth.
There are three sets or gear reductions in the qt50 motor, one on the clutch side, one one the output side and the last in the rear end. The clutch side is 33 to 63 teeth, the output side is 15 to 19 teeth and the stock rear is 10 to 57 teeth. With the stock wheel circumference of 1,422mm the rear wheel does 565.6rpm at 30mph. Engine rpm is 7,791 at 30mph. I'd heard stories that this little motor is capable of 13k rpm. At 13k rpm you'd be going almost exactly 50mph which I don't understand how cuz before swapping rears to the pw I was only hitting 32mph with a bunch of mods but still running my 50cc jug. I'm wondering what's the fastest anyone has got a qt50 while still running the 50cc jug and stock gears? And what they did to achieve it. Also I ordered my yt60 jug and piston etc. and they're on the way but I'm fabing a pipe and need the exhaust flange's port diameter for my pipe calculator, any one know what the exhaust flange's port diameter is or is it the same as the stock qt jug? Thanks and I hoped I helped some one by posting this info. Ryan.