This manual cam chain tensioner looks like a great idea , if only because it doesn't force the tensioner blade against the chain like the stock one with a big long spring . . My question to the forum is , at what mileage do you folks find that the stock one is starting to make noise ? I know , I know it depends how hard you ride , but just a ball park would be nice to know . Thanks guys .

 

I make the part so I am likely to possess a fair amount of knowledge from talking with riders along with my own experience.

The bad news is there is no general mileage. I've had people with less than 5000 miles, including my own experience with my 650 using a similar tensioner, need to replace the tensioner. I've also had riders with over 20,000 miles hit the point where their tensioner has failed. So it's not really miles sensitive.

The good news is that as the tensioner goes bad it is progressive and will cause a clicking sound from the cam drive, starting up around 4000-6000 rpm. It becomes clearly audible, you can hear it. At that point it is time to replace the tensioner, but it isn't at the point of possible catastrophic failure. If left without fixing, the chain will eventually have so much slack allowed under deceleration that it may skip teeth at the crank, which will make the piston hit the valves and break costly parts.

The reason is because it is a mechanical issue depending on tolerance stacking in manufacturing, along with the fact that the tensioner has a 1mm tooth pitch, but unfortunately the chain will seat in and wear in progressively (I call it dynamic wear). Once the chain wear/seating in hits an in between point the reversing pressure of the cam chain against the tensioner when the engine is decelerating, the cam momentum causes the back side to apply pressure against the tensioner and will snap the rack back in. My 250 was moving between 3/16-3/8" showing the wear on the teeth and polishing the underside of the plunger shaft. The kick back will round the teeth off over time, allowing the chain to snap back and forth further and further, the tensioner no longer securely holding the chain in adjustment. The spring in it simply pushes the plunger back in when the pressure is off. Think how often you downshift or close the throttle... you get the idea. Where the manual tensioner will hold the adjustment you have set, it will not wear, it won't move. The well lubed chain will slide on the guides as it is supposed to do.

So, listen to your engine and when you hear the cam drive rattle on the right side of the engine, replace the tensioner. I tell people no noise, no problem. But if you hear noise replace the tensioner.

I will say some people go to the manual tensioner early on, figuring why not. My brother did that with his KLX250. The really bad one was the KLX650 that had the tensioner toasted by 5000 miles and the second OEM unit failed before 14,000 miles - the first time I made and installed a manual tensioner. My Kawasaki 550 had cam drive noise at 12,000 miles, a manual tensioner took care of it - and put me in the business of making them. When I got my KLX250 with around 15,000 miles or so, it had the rattle, so I replaced the tensioner,

I hope that helps. You can email me at kriegercct@clems-garage.com if you have more questions or are interested in the kit.

 

Thanks for the very thorough explanation of the manual tensioner . My bike's only got 2500 miles on it but certainly something to keep in mind . You are a true asset to this forum .

 

Thanks, I appreciate your comment. My intent in my cam chain tensioner sales wasn't to get everyone to stick one in their bike, it was to help if they actually had cam drive issues. Nice part with the KLX and some others, the tensioner failure is progressive and has the characteristic of ticking, getting louder and over a wider rpm range as it gets worse. In other words it's telling you something is wrong. That is when I recommend riders replace the tensioner.

There is a really bad "fix" that some will tell about doing, they will loosen the tensioner until it clicks over then tightens it up again. Not good, putting a lot of tension on the drive and possibly pulling the cams into contact with the cam journals. Chains aren't meant to run under any tension. When it comes to the cost of a head if the cams score the head and a top end rebuild, the price of the manual tensioner is peanuts in comparison. Short cuts may cause more problems than a correct fix.

FWIW the old reliable Yamaha 500 single XT, TT, and SR series all had a manual tensioner, I think the XS650 twin did too. The old Honda ATC, XR, XL 200 and 185 had a semi-automatic tensioner, others may have too. Many racers in all kinds of motorcycle racing will have manual adjustments on the cam drives if running a chain drive.

 

The TT 500 that I campaigned in the studded tire ice racing class had a 540 kit , road race cam and straight pipe exhaust made some pretty serious hp and , as you say , with a mechanical cam chain adjuster never had a problem . When I sold it to one of Canadas top road racers and he finally blew it up it was the transmission that failled , not the engine .