Yeah, short of having a manual tensioner, the method you used is probably the safest by just pushing in on the plunger through that cap bolt. I did the same thing after reading Learjet's report some time ago, but if you think about it, the spring still isn't doing it's job. And in some cases the tensioner is even jumping back on the ratchet, which is what redpillar's case sounded like. This stuff has been quite interesting. I'm just tickled poop-less that we know what it is, and that it is fixable.

 

A stronger spring means increased slider and chain wear. If all it took was a strong spring they wouldn't have the ratchet in there. All the spring does is push the ratchet forware when there is enough movement to click it over the next tooth. You are forcing it over the next tooth which is exerting excess pressure and increasing wear. Sure it's quiet, but it's too tight.

That's why we went to a manual tensioner on the KLX650 when the top end got rebuilt, due to damaged cam chains and a couple toasted valves (my fault, adjusted valves too late) in 2001. We knew the spring wasn't the trick and that the tensioner would likely fail again in my bike. After some discussion and trouble shooting with some very knowledgable mechanics, I modified the stock one and gave tips on how to do it in the KLX650 forum. The lack of ability to do this with the Zephyr is what set up the tensioner sideline for me. No one makes it, but I needed it. I got a tip and made one - and five extra. Several KLX650 riders asked about them, before the Zephyr guys did. I was able to make them at a low enough cost that it wasn't worth bothering to do so for many others. Made me the "go to guy" for the KLX and now the Zephyr, along with a growing rep with Concours and Eliminators. Only the most do-it-yourselfers will take on the job, it's just not cost effective to gather the materials and do the work. I will tell you it isn't as simple to do a converted stock unit on the KLX250. The plunger design actually makes the pressure point off center from the already off center rack. It's a compound placement issue that took a fair amount of measuring and work to get it right in CAD. It is now right.

At this point I've taken the plunge and will have 20 bodies cut within about a week. I figure anyone that wants to go with a manual unit now will be able to do so by PMing or emailing me. I can give you the lowdown.


By the way, even with worn out chains (2 in the 650) and constantly varying cam timing, I didn't have any internal damage other than the chains and the tensioner due to the tensioner failure. The valves showed burning due to too tight clearances, so they were replaced as were the cam chains. We did a big bore at the same time, using a Vulcan piston which preserved the compression at a level to run 89 octane. If the chain doesn't show to be worn out the tensioner replacement will be sufficient. I think you can measure it by taking off the cam cover and doing so. It will amaze you just how noisy a loose cam chain and failed tensioner can be.

In addition I just spoke with an Eliminator rider who actually had his cam timing jump a tooth, but didn't have the valves hit and the cam chain is still in spec. He's ordering a manual tensioner to avoid buying the third OEM unit. We talked on the phone about the whole thing.

 

Okay, good thing it was the cam chain tensioner. Just from hearing the video, it sounded more like piston slap than the cam chain clanking. Hard to tell from videos sometimes. Thumbs up, now go have some fun riding.

 

Lots of good info here. PArts of this should be a sticky or put in the new FAQs

 

I've been poking around on here for the past week, and i'll make post #2 (yay).

I picked up klx250sf about two weeks ago, and i think at around 450 miles i am just at the beginning of this problem. Which i think is pretty odd for such a new bike. Bike had 0 miles on it when it was picked up.

Bike was broken in "the hard way", which is a personal preference... Break it in the way you are going to ride/drive it. Oil was changed at 300 miles, then took the bike on a 1.5 hour trek out to the forest for some trail riding. Bike had no symptoms/noise other than the typical noise a motor makes (before). After the first pull off: about an hour of riding at 7k rpm sustained freeway travel i heard the noise when decelerating in the off-ramp. Rode the trails for a few hours, and the noise only got a bit louder, was a lot more noticeable on the ride back home, on and off throttle.

What i am experiencing sounds like a heavy duty sewing machine clacking away between 4-6k RPM on acceleration and deceleration. Completely goes away at idle, or anything below 4k, and i cannot hear it over 6k. I can hear it with my helmet on easily.

Do you guys think this is the same problem? Should i wait to tick over the adjuster until it starts making the noise at idle? Don't want to make any rash decisions given it only has 600 miles on it now.

 

Turbo, you may have hit upon the best sound description of the KLX loose cam chain that I've seen to date...the noisy sewing machine that needs lubing and servicing. My wife has a Pfaff German-made sewing machine that got to making a raucous noise...needed a servicing that also involved some kind of timing adjustment. In retrospect, that thing sounded much like my KLX cam chain...maybe more so than the piston slap sound I usually refer to...clack, clack, clack.

I'm assuming you listened to Tweak's video/audio post. That's the noise of a loose cam chain...or an out-of-tune Pfaff sewing machine.

The absolute fix is a manual tensioner, but some may be uncomfortable with going that route. Something in the autotensioner in quite a few bikes doesn't get the job done.

 

I was just thinking this - since the cam chain issue has come up sooooooo much recently!

 

Turbo - definitely sounds like the tensioner. My bike only has about 4000kms on it and it only happened between 5K-6K rpm's.

i only rode a few hundred KM's with the noise and decided to to the manual adjustment... this weekend was the first real ride since the adjustment and i could not be happier! the bike is like brand spankin new now! smooth as butter.

 

That's the exact noise my bike was making. Except mine was loudest at idle and not so much at speed. It got really bad around 9000 mi, then spontaneously stopped about five seconds after I started it one Saturday morning, maybe the engine vibration made the adjuster click by itself? The engine is wisper quiet now.

Sounds like the KLX now has a "doohickey" of its own, another funky oem part that needs fixed or replaced.

 

Yeah it sounds close. It is hard to tell with the videos as the microphones aren't the best, and compression of audio when posted online. It definitely sounds similar. I'll give it a week and see what it sounds like.. should give me a chance to put another 200-300ish miles on it