The International CBX Owners Association

On a recent ride after downshifting from 4th to 3rd it felt like the chain skipped a tooth. The bike jerked a couple times and then all was fine. A few minutes later the same thing happened, also after downshifting. I stopped to check the chain and rear wheel movement in case the wheel bearings were bad but it felt solid as usual, no side to side wiggle. I couldn't duplicate the jerking after several attempts. At home I looked at the chain and both sprockets and everything looked fine. Is there something else I should check? I have over 66K on it and have a full Dyna ignition. Hasn't done it since and the bike runs great.

When is the last time you inspected the rubber insulators/cushions in the rear hub? they wear and dry-rot over time and can cause a clunk at take off and down shifts.

Hmm, hadn't thought about the crush drive rubbers. They're around sixteen years old. If one or more of them are chewed up or have shrunk that could be it. Thanks, I'll take a look. I remember the originals fell out when I opened the hub when I got the bike in 2002, mileage was 23,000+ then.

Jeff Bennetts wrote:When is the last time you inspected the rubber insulators/cushions in the rear hub? they wear and dry-rot over time and can cause a clunk at take off and down shifts.

I wouldn't have thought of that one either.
Wasn't J.R. making new cush rubbers.?

It sounds like a transmission issue to me.

Dave

Oh don't say that. There's no chance of a rear wheel lockup is there?

These downshifts that were made, were they throttle completely off, good positive shifts? I've had some strange shifts occur at different times, even with different motorcycles, that didn't completely go into gear and sort of skipped into gear. Is this what occurred? As Dave has stated, it sounds like a trans issue. If this is something that gets worse, it needs to be investigated. If it just happened a couple of times and doesn't happen again, perhaps it wasn't shifted correctly? Ride it some more and pay attention to what's happening. It's either going to get worse or was a fluke. Just my 2 cents worth.-Mike G

I think Dave and Mike are right. But before hanging your head in dismay, see if the shifter linkage is free and moving smoothly, and there isn't a bunch of slop in the pivots. Were you wearing shoes/boots that prevented positive shifts? Look for the simple stuff first. Good luck.

Good point Rick. I've seen shifter pivots nearly frozen due to lack of maintenance.

Dave

Did you ever resolve this problem? I had a similar issue with my CBX when it only had a few thousand miles on it but it would do it while in top gear and on the freeway at speed of around 65 MPH. I wrote it off as being the wrong chain - that is made to American specs and not Japanese. That was just a speculation but I became so worried about it I parked the bike and it still remains in my shop up to this day (from 1981).