Mechanical Versus Stock Cam Chain Tensioners

Contemplating whether to make this change or not as my bike heads in to have the valves adjusted.  Haven't made a decision either way yet, especially after 15 years and many, many miles without any problems.  But I do like failsafe when most of my riding is alone in the mountains, where the next vehicle to travel the dirt road I'm on could be two weeks from now.

Some discussion links over on ADV with the maker of a very inexpensive mechanical tensioner to replace the stock automatic tensioner.

https://www.advrider.com/f/threads/trying-to-bring-a-wr250r-back-from-the-dead.1601859/page-10#post-46522091

https://www.advrider.com/f/threads/trying-to-bring-a-wr250r-back-from-the-dead.1601859/page-10#post-46526185

Kreiger Cam Chain Tensioners

Strongly recommend against a manual tensioner. The arguments for it put forth in that thread display a stunning amount of engineering ignorance, and I was shocked when I read them back then.

johnkol wrote:

Strongly recommend against a manual tensioner. The arguments for it put forth in that thread display a stunning amount of engineering ignorance, and I was shocked when I read them back then.

Not for or against. But the guy selling those has been around the motorcycle pages of various flavors for years. As a mechanical engineer by training and employment, I don't think there's engineering ignorance there on the part of the guy who makes them. Unless another person who's also a P.Eng as he is can point out his engineering ignorance.

I didn't follow the back and forth much, nor who said what to who. I did have a back and forth conversation with him via the phone a few weeks ago. If I were to sum up the conversation I had with him it would have been "Yeah, you'll probably almost certainly never have a tensioner problem with the WR250R, but if you wanted to reduce the probability a manual tensioner would do that."

In other words, he probably spent as much time telling me I probably didn't need to worry about it as he did telling me he did make and sell a manual tensioner. I think his price was $30 a pop, or something like that. If it's about making a profit, he'd make more money if he spent an extra hour at the office that day instead of making a chain tensioner.

All that for background, there's nothing as suspicious as "I saw it on the Internet". I posted the links for info; my decision was to stick with the stock tensioner after I talked with the guy making them. (And he seemed fine with that and more interested in talking about the dual sport riding hear on the edge of Glacier National Park)

The argument that I remember was made, was that the manual tensioner was superior to an automatic one because it cannot move. But this is precisely its major flaw: you do want the tensioner to be able to move to take up the changing chain slack.

Not really sure what a P.Eng. is, but I'll give you that he's not a con man, just not a very good engineer?

johnkol wrote:

The argument that I remember was made, was that the manual tensioner was superior to an automatic one because it cannot move. But this is precisely its major flaw: you do want the tensioner to be able to move to take up the changing chain slack.

Not really sure what a P.Eng. is, but I'll give you that he's not a con man, just not a very good engineer?

A P.Eng is a registered professional engineer, in some jurisdictions just P.E.  The field of engineering they practice in varies - my brother is a P.Eng chemical engineer, which is far different than a mechanical engineer, or an electrical engineer, etc.

Other than that, your memory of what he said is pretty flawed (at least as how you recount what he stated is flawed), just as badly as I think your belief system was flawed when you claimed he was a con man.

The argument he makes is that the automatic tensioners MIGHT jump a tooth or otherwise not keep the chain properly tensioned.  He's pretty up front in readily acknowledging that, all in all, they're generally pretty reliable.

His explanation that followed that was the manual tensioners CAN move - but ONLY move when you move them, to the extent you want them to move (or not).  That's not a flaw - that's a feature for those who decide they don't intend to trust the automatic chain tensioner to never fail in properly fulfilling it's function.

For myself, with about zero posts in this forum since day one regarding WRR chain tensioners failing to operate properly, I chose to rely on the automatic tensioner rather than move to the manual tensioner to address a very long odds potential problem.

I don't see any problem with his engineering - except for those who believe they trust an automatic chain tensioner more than they trust themselves to include manual chain tensioner adjustments when necessary in their normal maintenance.  And then there's the ones like me that feel it's a long shot potential problem that doesn't justify making the change to deal with.

Jäger wrote:

His explanation that followed that was the manual tensioners CAN move - but ONLY move when you move them, to the extent you want them to move (or not).

Manual tensioners cannot move dynamically, and they need to for greater engine reliability, that's why auto tensioners have taken over.