Chinese comet 780 clutch
Despite buying my clutch from a reputable place, it is looking like I have a Chinese knock-off.
I noticed a week or two ago that the moveable sheave of my clutch was wobbling quite a bit. With the engine off, if I grabbed the sheave at the 9 and 3 o’clock position, I could rock the sheave side to side. I ordered a new sheave from beltpalace.com along with some different weights and springs to test out.
My back is still sore and I didn’t want push it by pulling the engine out of the cart. So I dropped the swingarm instead:
The first thing I noticed was that the locking plates weren’t bent over on the bolts holding the roller arms in place.
This is how I pulled the spider off the hub. The 2nd thing that was strange was that I had to use metric M6 bolts to thread into the spider. Glad I still keep a container full of bolts from the Japanese dirt bikes I’ve owned over the ears. I thought that Comet was a U.S. company and expected them to use standard threads/bolts.
And this is how sloppy the hub and moveable sheave are:
The bushings that the guide pins ride in were well worn. The scary thing is that this clutch has less than 75 hours on it!
So finally on to getting the clutch put back together. The hub bushing and casting around the bushing were thicker on the new sheave compared to the original:
I tried to thread the M6 bolts into the new sheave and they wouldn’t go. Turns out the new hub is threaded for 1/4″ – 20 threads. But it wasn’t until I tried to slide the new sheave over the hub that I that it became painfully obvious that this wasn’t going to be an easy project. The new sheave didn’t come close to sliding over the hub, the ID of the bushing was too small.
So I sat back and tried to figure out what to do. The evidence certainly pointed to my clutch being a cheap copy – it wore out very quickly, all the threads were metric and the lock tabs weren’t bent over. I was feeling pretty confident that beltpalace.com was selling OEM parts or at least OEM spec parts. The springs and weights were all bagged as Comet parts.
And if the new sheave wasn’t made by Comet, it was at least a better copy with standard threads. I finally decided to make this sheave work. I doubted I could find a knock-off sheave that would fit my clutch and it wouldn’t be worth it as it would wear out quickly as well. After about an hour of working on it, I finally got the new sheave to fit over the hub. I had to run out to the hardware store to get three 1/4″-20 bolts. And after installing the springs and weights, I made sure to bend over the locking tabs.
I also had to take some material off the sheave so it would slide up high enough and not interfere with the spider.
Now I just need to get the clutch put back on the engine.