Overview: Jigsaw’s Cam Chain Tensioner

Yes, the master of pain and suffering designed this confounded piece of equipment.

Almost all of today’s new motorcycles come with an automatic cam chain tensioner. The overall opinion on them is that they are crap. Apparently, its an inherently faulty design, especially since most manufacturers try and make them fail-proof. Haven’t they heard of entropy? A better design would be one that’s easier to maintain…. The one on my 250 is light years ahead of the old style tensioners, which were just tubes with a spring in between… The new style is more reliable, the old style is easier to maintain. Arg, I’m so torn! I’ve found that if maintained, the new style tensioner is not a bad unit for daily riding/use, but it is still seriously torturous to rebuild the darn thing! For a race bike however, I’d go a manually tensioned unit from APE racing or similar.

A Manual cam chain tensioner from APE racing. Be careful when using these not to overtighten the cam chain. A bit too loose is better than a bit too tight.

Why is the tensioner such a big deal? Well, it needs to be removed during every valve adjustment, which inevitably causes it to be exposed to the elements, if you’re Mr. Perfect Mechanic. It’s designed to be sealed from the outside world with a rubber gromit and bolt, but like so many other threads on this bike, the threads strip out very easy, causing it then to have leaks and get all kinds of moisture in there. Add the crazy heat changes it experiences from sitting in the cold during the winter and coming up to running temperature,  sometimes multiple times a day and it’s insides become a breeding ground for iron oxide, also known as rust.  In this case, I can’t rationalize the rust as natural weight reduction… I guess I am a bit self-defeating in this post, because if I had more money, and/or didn’t ride so much (to necessitate so many valve adjustments), this wouldn’t be an issue. Fortunately for my sanity, I AM a motorcycle addict and must ride to keep my composure, so I learn to deal with the extra wrenching. Right, onto maintenance!

The easy way to maintain it would to clean it with WD40 EVERY TIME you do an oil change. If you can’t or aren’t willing to do THAT, AT LEAST every time you have a valve adjust done….. Squirt that stuff into every opening you can find on the silly thing, and thoroughly work it through. You’ll be surprised how much rust you can get out that way. It’s time consuming, and it gets tedious, but it’s EASIER than what I’m about to show you…. Only read further if you’re a bit of a masochist.

If you are inclined to exact a bit of brain damage on yourself, make sure you have a second pair of hands reserved for the rebuild. First, remove the cam chain tensioner from the motorcycle and slip this little clip towards the BACK of the tensioner. DO NOT take it off the front and leave it laying on the bench:

















Take the tensioner apart, clean and lube all the parts. I’m finding thick lithium grease works just fine!

Put it all back together, making sure the outside spring clips into the body where it’s supposed to:

You might say: “That’s easy! What a whiny wimp this guys is, eh?” Well, this is the tricky part, the part that will make you cringe, cuss and generally want to destroy this stupid little piece of hardware. You have to compress the outer spring by “tightening” the tensioner, which causes the expansion rod to compress the inner spring in the opposite direction than the outer spring, all while NOT pushing the inner assembly out of the outer assembly. You’ll know it’s compressed enough when you can’t fit the plate-lock at the bottom into the notches because the spring is wound too tightly. Back it up a few turns and it should fit in. Keep in mind the plate lock is keyed – meaning it only fits in with a specific orientation, so keep rotating it until you find it fits. Once you have the plate lock back in place, move the clip back over into it’s clipped position. Then you can let go of the tentsioner and it should stay together, and have a positively strong force pushing out the tensioning rod.

If after taking your tensioner apart, and reading this post, you still can’t figure out how to do it, I would recommend you just put it in a box and send it to me. I’ll rebuild it for you for $30. I have the second set of experienced hands you’d need. If you want to attempt it on your own, I’ll do my best to explain, but I won’t be removing it from my bike to take pics again…. THIS IS NOT EASY MAINTENANCE. YOU HAVE BEEN WARNED!!!

On to the next project, stay tuned!


About Dandooligan

Dandooligan CO, United States Every ride spurs the yearning for another and as such, has pushed me to adopt the riding lifestyle and all of it's challenges. This blog concerns those challenges from bikes to gear, media about bikes, and maybe even some psychology/sociology on the subject as well. Dandooligan, a mash-up of Dandy and Hooligan, both very important parts of me and my outlook on life. I'm also known as Spooph

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