KZ750 CSR Twin Cam Chain Tensioner

So I've been hearing a noise for a while now (since I purchased the bike in may). I didn't think much of it till recently. It sounds somewhat like a hand held grinder running (not being used), but faint, and the pitch never changes with rpms (does it idling as well). I chocked this up to normal engine noise as I've been riding the bike daily and it hasn't gotten any louder. Until recently...

Over the last two or three days, the sound has gotten louder and the bike has been vibrating much more. I recently hacked off the rusted out and cracked stock mufflers and welded up some extensions and turn-downs to the stock exhaust. This made the exhaust quite a bit louder and also increased the vibration marginally. I've been riding this way for about three weeks with no problems. Over the last two days or so, the vibration has gotten progressively worse. It didn't really happen all at once like something broke loose. The whining has gotten louder too. I went over it last night with a stethescope to see if I could pinpoint the problem area.

The sound appears to be coming from the front of the engine, particularly from the protrusion on the bottom front and the valve train area. This makes me think the cam chain may be out of adjustment. So I am in the process of adjusting the tensioner. Here's my question...

The tensioner piston barely moves in and out and when it does, it does so abruptly. It sits at the innermost point for more than 1/3 revolution, then pops right out to furthermost point. I thought that maybe there was some slop, so I kept my finger on it, and same thing. Does this sound normal to anyone? Also, will it hurt anything for me to remove the tensioner for inspection? I really don't want to be dropping something down into the cases and have to tear stuff down to put it back together. I'm hoping that the cam chain isn't completely worn out and that I can adjust a few things to get me by for the next few months, then I can tear down and rebuild over the winter.

I'm in the process of going over all the fasteners to see if that fixes the vibration problem. I'm also going to check valve lash this weekend as well and give it a once over before hopefully riding down to D.C. on Sept. 11th.

Almost forgot... Bike had about 13,250 mi. on it it when I bought in May. It now has 19,600. That should give you an idea of usage.

Daryl wrote: The sound appears to be coming from the front of the engine, particularly from the protrusion on the bottom front and the valve train area. This makes me think the cam chain may be out of adjustment. So I am in the process of adjusting the tensioner. Here's my question...

The tensioner piston barely moves in and out and when it does, it does so abruptly. It sits at the innermost point for more than 1/3 revolution, then pops right out to furthermost point. I thought that maybe there was some slop, so I kept my finger on it, and same thing. Does this sound normal to anyone?

That's how it works. The in/out movement is very slight. Do not set too tight.

Daryl wrote: I recently hacked off the rusted out and cracked stock mufflers and welded up some extensions and turn-downs to the stock exhaust. This made the exhaust quite a bit louder and also increased the vibration marginally.

It probably also made it run very lean and could cook the engine.

Thanks for the heads up on the tensioner.

As for the exhaust... It's the not but maybe 4 inches shorter than the stock system that was on and the baffles were taken out of the stock system (and I was told rejetted). So, there shouldn't be much of a difference in flow or length. Would that really make that big a difference in mixture? I haven't noticed any difference in the bluing on the pipes at the manifold. neither to color or length.

Daryl wrote: Thanks for the heads up on the tensioner.

As for the exhaust... It's the not but maybe 4 inches shorter than the stock system that was on and the baffles were taken out of the stock system (and I was told rejetted). So, there shouldn't be much of a difference in flow or length. Would that really make that big a difference in mixture? I haven't noticed any difference in the bluing on the pipes at the manifold. neither to color or length.

I'm not sure what you're saying. Are you saying it has the stock exhaust system that someone cut and removed the baffles from? If that is the case, there should be no bluing of the pipes at all unless the engine is (or was) running too hot. The stock exhaust headers are double walled and under normal operating temperatures do not turn blue. Ed

Upon further inspection... it appears that the whirring noise is coming from the balancer assembly.

Somehow, I think I'm going to be forced to be done for the season, unless I can get lucky and figure something out.

650ed...

When I bought the bike, it had stock exhaust. The baffles were removed (which I verified). I was also told that it was re-jetted to accommodate the change. At the time of purchase, there was bluing (although not quite blue) on the pipes for about 2.5-3 in. It was normal chrome after the initial bend. I expected this was normal as it happens to many bikes, but as you said, the exhaust is double-walled and I had not accounted for that possibility. I've only ever worked with single-walled exhaust and headers.

So, it would seem as though as though that my have caused pre-mature wear of something in the balancer region, which is where the noise is coming from.

I guess it's another expensive mistake... But that's become the story of my life.