I don't know if this information is pertinent to our KLX's but thought that I'd pass it along.
Ever since I rebuilt the top end of my sons RMZ 250, it has had a rattleing noise in the top when it was cold. As it warmed up the noise would quiet down. It was similar to what some of you have described prior to KACR / Cam (or whatever the actual problem is) failures. So anyway last night my son was concerned enough that he got me envolved one more time. We removed the valve cover and checked the ACR. (Now I need to tell you that the ACR on his RMZ is not exactly like the one on the KLX, but it is basically a Kawaski engine, and the principle is the same. The RMZ ACR has fewer moving parts than the KLX but operates off of centrifical force in the same way.) I checked the spring and it was ok. Checked the action and all seemed to be okay. Then we slowly turned the engine over and watched the release. When the paw came up it hung up on something and as soon as it cleared into the valve cover area it snaped back. Ah Ha! So I looked closer and detected some very light scratching on the side of the release paw. I rolled the engine over to where the paw was inside the rocer box and moved it with my finger ...... IT STUCK OPEN!!!
Now I'm curious as hell as to why this thing is sticking on the side of the rocker box. So I remove the cover gasket and check it again. It doesn't stick any more. So I inspect the inside of the gasket and there it is!!! The round parts of the gasket are touching the ACR and causing it to hang up. They are made of aluminum and coated in rubber, but the rubber has been worn away and now shiny aluminum is showing in one spot. So a new gasket is in order and I will check clearances closely when I install it.

Now for the KLX: The ACR's are a little different. The gaskets are different too. But is it possible that the tollerances between the gasket and the ACR are close enough that if that portion of the gasket gets pushed inward ever so slightly on installation that it causes the ACR to hang up on it. In our situation it really doesn't effect the way the engine runs, because the ACR is fully expanded while running anyway, but it does make the noise and because its actually rubbing on something eventually it is going to fail.

So maybe some of you with this niose can remove your valve cover and check for this.. I'm not saying that this is the problem but had I not went through the steps that I did, I wouldn't have found it.

 

are you talking about the valve cover gasket? the acr isnt even close to it.... [&:]

 

Very interesting to say the least. My mechanic did tell me that the point that the exhaust cam was attached to the camshaft was loose, sort of riveted on, but he did say that it would probably do it again in time, not the news I wanted to hear, but then again I bought the 4 year extended warranty, and while most people questioned adding a warranty to these "Bulletproof" bikes, I opted for the extra warranty just in case.........and this time it payed off.[8D]

 

I'm really anxious to see your set up cause my acr is less that 1/8" away from the valve cover gasket. The rocker box is split in half ... the top half being the valve cover and the bottom half being the head. Your cams are positioned so that they are half above and half below the rocker box split. The ACR is on the end of the exhaust cam right next to the outer rocker box which has a gasket. Does yours look different than that?

 

um..... not sure.... i have only had the valve cover off once.... i maybe mistaken... it sounds like you know more about bikes so you are probably right....

 

Are you referring to the outside edge of the cap, or the edge inward as is leads into the spark plug cavity?





I don't think there could be any rubbing on the outside edge, but maybe with edge that leads into the spark plug cavity. I never tried spinning mine with the KACR expanded to see how close it gets, but it looks like it could get pretty close.

 

On the RMZ it was coming in contact with the outside edge, but the configuration is a little different. It does look like its pretty close to the edge leading to the spark plug.

I don't know that it means anything, just thought I'd share what I found and see if something similar could be happening with the KLX.

The biggest difference is that the ACR on the RMZ is attached to the timing chain gear, but the ACR on the KLX is on the oppisite end of the cam as the gear.
Probably not related, but something to think about.