[KDS4444]

I am the original owner of a 50cc Yamaha Zuma. I've done a lot of servicing to it myself over the years— I've replaced both tires, I've replaced the head gasket, and I've put in new front brake pads, but it wasn't until recently that I had to open up the crankcase.


The scooter had been running more or less fine, but I was at a traffic light a few weeks ago and the guy behind me actually got out of his car to tell me that he was a motorcycle mechanic and that my scooter was running rich and needed adjusting. And that my rear tire needed air. I thanked him, got the scooter home, put air in the tires, and went to adjust the carb.


The rear tire had also been rotating with some difficulty, so I figured as long as I was adding air, I should probably check the brake shoes (which had never need replaced since I bought it). I got the tire off, removed it, looked at the shoes, but they were still within spec. so I decided to keep using them.


Still, the gear for the tire was turning only with some difficulty. So I opened up the crank case to see what was going on in there. As soon as I did, I discovered that both of my clutch springs had long since broken off and were rattling around loose inside the case! I ordered replacements, and when they came, I removed the clutch bell, clutch, and v-belt, took the clutch apart, replaced the springs, and put it all back together.



Once I had the crankcase closed, I fired her up. She started just fine. I adjusted the idle and played with the air jet until I had what sounded like a good rpm, then rocked her off the centerstand and tried to take her for a drive...


...It was like driving through molasses. When I opend up the throttle, I got virtually no power. The engine did not rev, and there was almost no speed coming from that back tire. I had to use my own feet to get her to go up a gentle incline. But omce at the top of that incline, she flew downhill and sounded and acted perfectly normal. Once on the flats, she returned to only a few mph.


I opened up the crank case again. I started the engine with the case off to see if the variator and clutch were working correctly. They were not. Not only was my bell rotating much too soon, but revving the engine only appeared to make the variator and clutch spin faster— it did NOT appear to change the pulley ratio!



I took the clutch back off. I had thoroughly cleaned it when I had it off before, and regreased it (including its pins), so I was pretty sure the problem wasn't there. My v-belt was the original one, and it was down to 14.6mm from the original 16.6— I've ordered a replacement, but while I am certain that will make things work better, I dopn't think it is the problem per se.


I then had a look at the variator. I have never had the variator off before, and am about to remove it. Right now it rotates on its spindle, but I can't get the drive faces to move apart— they seem stuck close together. With the v-belt off, I can't get either one of them to move. I can hear the rollers rolling up and down as I turn it, but the drive faces don't budge.


I am about to take a socket wrench out there and get the nut off (wish me luck!) and then see what I can see. But if anyone else has any ideas or suggestions for me, I'd sure appreciate it. Thank you!!