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Krieger Cam Chain Tensioners!

I did not intend to make this product. It came out of necessity. Both of my two Kawasaki motorcycles, a KLX650C and a Zephyr 550, had “automatic” cam chain tensioner failures. The KLX had TWO tensioners fail, one at 5000 miles and the other at about 13,000 miles. After the second tensioner failed the cam chains had to be replaced. I had the top end rebuilt at the shop where I sold bikes part time, I was a quality engineer at that time. I had the skill to do the work, but it was easier to sell bikes to pay for it to be done by the mechanics, who are friends too.

Originally I joined the Yahoo KLX650 group for information and asked there about the cam drive noise.  The response from the riders was "It's normal.  All Kawasaki engines are noisy."  I figured they knew.  I replaced my failed OEM tensioner at 5000 miles with another.  I listened to the comments at the time and rode on proving ignorance was bliss - until the engine wouldn't start and run at about 15,000 miles and a lot of clattering.  I was not thrilled.  I loaded the bike in the truck and took it in, saying "make it run" to the guys.  I knew it would get done quicker with them doing it and I'd pay for it with bike sales.  They fixed it - new cam chains and a decision on what to do about a second failed tensioner. 

This time I wasn't "drinking the Kool Aid" that noise was wrong.   I looked at the second failed tensioner using a magnifier. It was clear what the problem was.

The way the adjuster works is as the chains wear the tensioner will have a light spring push in against a plunger with a toothed rack stem. A pawl is supposed to lock the rack when it moves in. The problem is when the plunger moves in very small amounts the pawl may just barely slide over the top of the tooth and any back pressure from the cam chain drive will snap it back over top the tooth. That will round off the edge of the tooth and pawl, eventually allowing the plunger to push back and forth over 3-4 teeth of the plunger. I could see the damage by the polished tooth tops and the magnifier allowed me to see the edges were rounded. Here is an example:

This tensioner movement back and forth will allow chain whip and snatch in the engine. That will cause valve timing issues in starting and running and will wear out the cam chain (chains in the case of the 650, it uses two chains). 

The mechanics and I had some discussions on what to do. We came to the conclusion I should make a manual tensioner. I modified the stock tensioner for a through bolt. It wasn't particularly easy, but it worked well, except that it seeped oil a bit. Still I put on nearly 30,000 more miles with about 4 adjustments during that time plus another few thousand with one of my tensioners on it and everything is working like day one.  The first three adjustments were fairly close together as the new chains seated in.  At this point I do not remember when I did the last adjustment, but the engine will tell me when it's needed by the light ticking from the cam drive when the engine is fully warmed up.

Key point:   No ticking, no adjustment needed.

I did and will do tension adjustments on the 650 when I hear ticking from the cam drive when the engine is fully warmed up.  The actual adjustment is very small and I know fairly accurately how snug the cam chain tension is. The manual tensioner will allow light ticking when the engine is cold.  There has to be a few thousandths of slack when cold to allow for thermal expansion of the engine components.  Once warmed up there should be no ticking in the cam drive.

The key point is the cam chain should only have the slack taken out, not actually have tension on it. Perfect adjustment would be zero pressure/no play. Still a little loose based on variability in adjusting a manual tensioner is relatively insignificant when compared to the stock “automatic” tensioner what will allow ¼ to ½ inch movement of the plunger. One full turn of a manual tensioner will be less than ¹/₁₆" (about .050") and you will definitely hear ticking if you are even ½ full turn loose, hand tightening will not allow you to be one turn tight.  In addition, when the lock nut is tightened the adjuster bolt will not back off at all.

Some people will try to use the stock tensioner in a manual method by backing out bolts until the pawl snaps into a tooth then tighten up the bolts. This is significant tension and will wear both the tensioner shoe in the engine and the cam chains.  I've also heard where riders pull the cap off the tensioner, remove the spring, stick something inside the tensioner and slam it forward, again overloading the cam drive...

Think about that - your cams run in a plain bearing machined surface in your head and you are forcefully pulling down on them by over-tightening the cam drive with either of those two jury rig methods.  What do you think could happen should that force cause a cam to break that few thousandths film of oil between it and the head when the engine warms up and everything expands a few thousandths?  I think I know, and I don't want to go buy a new head.

 I even had one KLX owner who thought it was no big deal to replace cam chains every 12,000 miles!  HyVo chains are known for durability and run a lifetime in many engines, even being used for primary drives.. 

All to avoid buying a manual tensioner for about thirty-five bucks that would eliminate the headaches and with clear instructions, be easy to live with.

Back to the story… the KLX is alive and doing fine after over 30,000 miles with the modified stock unit and now my own tensioner.

Then I bought a Kawasaki 550 Zephyr, I like that old school superbike look...

Obviously, the bike on the left...  That was the bike that started this whole thing.

I rode it a bit and the top end was buzzing like a hornet’s nest, rarely quieting down when the tensioner tried to work. I had a pretty good idea what is wrong, but I still asked on some forums. The biggest response I got was “It’s normal, all Kawasaki engines are noisy." and “It’s primary drive chain noise.”  This time the BS detector started going off, considering what I'd been through on the KLX.  I knew that whole "All Kawasaki engines are noisy" thing was pure crap.

I eliminated the primary drive noise possibility by doing the simple test of putting the primary chain under tension, which eliminates the sort of light slapping noise. I put the bike in gear, held the brake, and lightly eased out the clutch power-braking the bike slightly. Most all primary noise will go away. My “hornet’s nest” didn’t. One or two riders actually did mentioned the tensioner failure and Kawasaki had some history of tensioner failure on sport bikes... and, as I learned, on other models too.

 So, out came the tensioner, it was definitely not functional. It was not able to be converted to a manual unit as the KLX had. Kawasaki’s "new improved" replacement was essentially the same tensioner that went bad TWICE in my KLX. No way that’s going in my bike. I figured I’d pay the $50+ for an aftermarket manual tensioner, but wonder of wonders, my bike is not listed and a call to the supplier verified they didn’t list or make one specifically for it and they had no clue what might work - nor, obviously, could they care. I measured up the length needed to reach the cam tensioner slider in the engine and emailed the information to the most well known tensioner manufacturer asking if their GPz550 tensioner would work, the body was exactly the same but was the bolt reach long enough? I also asked if the bolt reach wasn't long enough, could they make one with a longer bolt? I got no response from the company. (Oddly enough they now make one for my bike... imagine that.)

So, with a bit of inspiration from a fellow Zephyr owner, I grabbed a chunk of ½" aluminum I had and made my own – and four extra for both the Zephyr and KLX. I bolted in one of the Zephyr tensioners and did an initial adjustment, snugging up the bolt by hand while turning over the engine with a ratchet to get the slack on the tensioner side, backed it off about ¹/₈ turn to allow for thermal expansion, and when the bike fired up – NO MORE HORNET’S NEST BUZZ! Talk about happy.  Now with over ten thousand miles still no noise - and no adjustments… Yeah, “It’s normal.”… my foot!

The KLX tensioners sold almost immediately, the Zephyr tensioners caught on slower.  The KLX really has a lot of stress on the cam drive.

Now, to date I've sent out several thousand tensioners.  I haven't checked, but I believe they're in all 50 United States, all Canadian Provinces now. They are in over 40 countries around the world, a few of the more unusual to me were Kazakhstan, Latvia, Czech Republic, Thailand, Russia, and Malta.  It just amazes me the power of the internet and forums.

Part of the fun was doing stickers too.  I find it really interesting to think that there may be bikes around the world with the Krieger Cam Chain Tensioner sticker on it.  Part of the fun for sure.

One deal that was really cool was the one sold to a WERA vintage middleweight/heavyweight superbike racer.

I do use the parts I make. I took the converted tensioner off my KLX and put on one I made before I sold the first one for a KLX. I also rode my Zephyr with the tensioner in it before I sold the first one of them too. Unfortunately I can’t do that with every model, but I know they work as intended.

The kit is made as I would like to have if I bought it from someone. I figure the flush head fasteners open up the lock nut so a wrench will fit and turn, plus it looks good. I made an O-ring seal so it won’t seep oil like the conversion did on the KLX. I used 6061T aluminum because of machinability and corrosion resistance. I include the OEM gasket from Kawasaki (and other manufacturers on those tensioners) because you will possibly need it. Finally I include the directions for installation, which apparently the others do not.  OH!  Can't forget the stickers - I had to have stickers.  Not just any sticker, but something that was good.  I hate lousy stickers.  I have tested them on the back window of my truck - two years out in the weather, no fade or peeling.  Good stuff... gotta have good stickers.
 

As I said, I didn’t intend to be doing this, but I am and it’s fun. I hope I can help you out with a reasonably priced part to help keep your bike running great.
 

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