Zuma rear wheel locked after overhaul

[KDS4444]

I recently did an overhaul on my 2002 Yamana Zuma YW50 (49cc 2-stroke), a thing I have never done before. I replaced the v-belt, cleaned up the variator, and replaced some missing springs from my clutch shoes. I also opened up the gear box, removed and then replaced the main drive gear, and replaced the transmission oil with some fresh ATF. I noticed when I was done that my engine had/ still has a small leak between where the exhaust attaches to the cylinder, but it was driving just fine, had much better pick-up, and no more smoke coming from the exhaust. That was about a week ago, and I haven't driven it much more than an few miles since then until today.


Today I took it for its first long drive, about 10 miles round trip. I got to about mile-4 when as I was accelerating through an intersection, the engine died on me. Also, the scooter didn't just coast to a stop, it was like the rear wheel had somehow locked up on me. I could smell hot rubber, but figured this was just the new v-belt getting situated. I opened up the crank case, found nothing wrong. Closed it up again and restarted the machine. Seemed to be fine. Got back on and kept on driving. Around mile 6 it happened again: opening up the throttle began to make the scooter move slower, not faster, and I dropped from around 35mph to less than 5. The engine didn't sound happy. I was able to keep it moving a little while longer (maybe 200 feet), but I knew I was doomed. When I finally came to halt, the rear wheel would not move at all— not like it was stuck by the rear brake shoe, but as though the gears in the gear box were not allowing it to turn. I put it up on the kick stand, and the rear wheel will move just a few degrees in each direction easily. If I put it back on the ground and push it hard, it resists me but it WILL turn. Also, I can hear what sounds like the engine starting up again, though there is no key in the ignition and it is turned off! It's as though the rear wheel is turning the variator and trying to start the machine up.


I ended up parking it along the side of the road and catching an Über home. Tomorrow I will need to go back out there and try to fix it, but I have no idea what could be wrong. I was not able to identify anything actually burned or overly hot around the crank case, but the smell of hot rubber persisted. My v-belt looked just fine when I opened the crank case up at mile 4. But the scooter is stuck now!


Am eager to know if anyone has any ideas what might be wrong! I sure don't!