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What I have learned about cam chain tensioners over the past few years of doing the Krieger tensioner.

I hope this is of some help in understanding the whole process. It is what I've learned both from the rebuild time when we, the mechanics who built the top end (I was selling bikes well enough part time I knew I'd get the work done faster by them than doing it myself and could afford it) and I, decided a manual tensioner system was the best route.  All the work, reading, and thought process in the past ten years since have proven the choice a very wise one. It is not a guesstimate in the mechanical aspect, but it is not a statistically proven situation since I only have had a few engines at my access. There is the back up from a few hundred other riders who have either made or bought manual tensioners for their bikes; KLX/KZ/GPz/ZR/ZX/ZL/ZG and DRz.

Not all automatic tensioners fail so I have one comment before starting out –

“if it ain’t broke don’t fix it.”  No cam drive noise = no tensioner problem, why bother changing it.  If it ever goes, fix it then. 

I know some people would do the manual unit just because.  At this point, I am that way, but it isn't necessary.  If the indexing falls in place properly for the mechanical requirements they will work. If it doesn't they will fail. 

There is one exception.  The Honda VTR1000 can have catastrophic failure of the front cylinder tensioner, which can take out the head and piston - the thing doesn't just quit working, IT BREAKS!  If you have a Honda VTR1000 Superhawk/Firestorm - FIX IT NOW! 

Otherwise you usually have a thousand or so miles buffer before damage will start occurring depending on the model of motorcycle.

Those tensioners that do fail have taught me the following:

The thing I've found interesting in both the KLX and some other forums is the expectation that Kawasaki engineers are infallable and that replacing these tensioner parts and resetting supposedly automatic tensioners would be a normal practice. If it is automatic shouldn't it be automatic? Why should I "reset" or back out until I hear a click, effectively doing a manual tensioning and also making it too tight? I don't buy it. One guy on the KLX site thinks it's okay to replace HyVo chains at 12,000 miles. Those chains are the same design used in some automobiles that run for about a lifetime and on the primary drives of many in-line fours. Other guys think it's okay to back out the mount bolts to effectively override the automatic system and over-tighten the chain..

Now to address what I observed before making my first manual tensioner. The rack and pawl design with a spring will constantly put some minimal pressure on the chain slider which would promote wear. The spring isn't strong enough to resist kickback in the chain under crank deceleration, so it isn't of any value in tension control in that area. What it does is put enough pressure on the rack to push it forward and the pawl clicks in as the chain seats in and cam drive wear occurs… but not always completely.

The key point is that the automatic tensioner clicks in incremental amounts.  Cam chains wear/seat dynamically (no increments). When the wear, which by my manual tensioner adjustments has proven to be minimal, isn't enough to move the rack forward forward enough to seat in, but just barely over the tip of the tooth there will be problems. And of course there is no way to tell this.  Under cam drive deceleration the rack can kick back hard enough to force the rack back over the pawl, damaging the edges of both by chipping off the edge.   The pictures of a new ZX6RR tensioner I picked up off ebay as a pattern for the ZX6RR manual unit, shows the wear...

 

Notice the ninth tooth up has been chipped, the pawl does not seat square to it so the chip is off to the side.  Then there is the wear pattern showing the constant push back over five teeth, the fifth just starting, and clicking forward again over and over.

Another view of that same wear pattern.

I just started a tensioner for the Suzuki GXF1250 Bandit.  I had the rider who requested I do them send me his tensioner - good Lord what an eye opener:

Notice the two teeth with the chipped edges and the repeated wear on several other teeth as the tenisoner keeps ratcheting back.  Now for the eye opener that I missed on my ZX6 tensioner (it is there, but not as vivid):

Look at the wear on the back side of the ratchet rack!  That thing has been pushing in and out so much the shaft is polished!  Now what do you think that's doing with the cam chain and the valve timing?

 This is the same effect as the rounding of shifter dogs when gear boxes are abused with incomplete or missed shifts, but on a much much smaller scale. It takes a magnifier to see the wear (actual rounding), but not the evidence of the wear (polishing of teeth). If this occurs over and over the edges round, much like shifter dogs can, but eventually the rack may start skipping over multiple teeth.

I was going to resell that ZX6 tensioner after using it, but I couldn't screw someone over knowing what I know.  It's in a baggie in the garage.

I really don’t know why the earlier goofy spring and thread design on the Zephyr 550s fail, I could care less, I just know the ones on the Zephyr 550s regularly crap out.   Someone had actually screwed with and messed up the one on my bike apparently trying to make it work consistently.

After two of the OEM tensioners in 15,000 miles, the second one costing $70 initially and then about $300 in rebuild costs after it failed, I have no qualms about recommending a manual unit. With simple adjustments on an "as needed" dictated by faint clicking when fully warmed up, which will be at fairly wide intervals after seating in of any new components, the unit is reliable as a rock. I've got over 30,000 on my bike with a manual unit, I can't remember now when the last adjustment was made, but it still isn't making any rattling noise except when cold and that is due to play allowed for thermal expansion. Less than one full turn of the adjuster bolt, .050" movement per turn, in four adjustments over 30,000 miles. It is so small a movement if you look at the OEM rack you'll understand why it is possible to have one go bad and another one go without issue. It's just not worth the $70 for the automatic one if it fails again. The manual units are more reliable, the biggest problem with them is when a rider doesn't recognize when it rattles it is time to adjust it.

Installing a manual adjuster in an engine with seated in parts there may be no adjustments for long periods of time/miles.  I have yet to need to adjust the one in my Zephyr with over 10,000 miles on the manual tensioner.  I also have read where another rider using the Krieger tensioner in his Concours. He had over 23,000 on his with no adjustment yet.  The "frequent adjustment" myth is just not true.

Now if you adjust the manual tensioner the way I describe it, or another way I learned from the Eliminator owners, you will have taken virtually all the play out of the cam chain drive, but put virtually no tension on it. The OEM automatic tensioner's spring actually does put unneeded tension on the drive all the time, pushing in. Ideally, all that need be done is take out all the slack.

The play is taken out by either listening for the rattle caused by the loose chain play, which can also be felt if actually doing the turning in by hand. I will tell you I put a socket on my inch/pound torque wrench, held it and twisted as hard as I could... I couldn't even get the beam to deflect. So obviously hand tightening is nearly impossible to overtighten, but I still go by the sound and feel.

Since this is all done at full operating temperature everything is already thermally expanded to probably a thousandth or two of maximum growth over all, all inclusive. In other words the drive is as tight as it will get due to expansion. This will result in a very tiny amount of slack when the engine is cold, but that slack is so little it will be inconsequential as my high miles show it to be.

With some bikes having the adjusters so hard to get to and knowing just how close the cold set makes the adjustment, I have started recommending riders not really bother with resetting the adjustment with the bike fully warmed up and running.  The adjustment is usually less than a quarter or even an eighth of a turn, which is around .010" at the most.  That's nothing compared to the movement allowed by that skipping of teeth in that picture above.

As for the HyVo style chain, those chains are the same design used in millions of old pushrod style automobile engines and on the primary drives of many in-line fours. HyVo chains are known for durability when bathed in oil - which they are. Do the research on the internet, I did. I also have never seen a HyVo cam or primary chain actually break in the 22 years I spent in a mid-size dealership where I used to love to go hang out in the shop.

The one thing I have seen is damage caused by loose cam chains beating up the sliders, variable cam timing as the chain slack allows it to vary by a large amount when the tensioner allows .250 movement when the rack pushes back and forth over 3-4 teeth, and overly worn cam chains from that slapping and snapping around. I will say I did see some Honda ATC200 engines, which use a roller chain, that didn't have the manual adjustment done on them at all, resulting in a lot of chain slap... enough to break the tensioner sliders in them and actually cut through the cylinder cam drive tower area on one. Incredible!

Now the negative points on the manual unit. You have to be aware of any ticking coming from the cam drive area when it's hot, so you can know when to adjust it. That's an actual audible signal that is far quieter than the clatter from a failed OEM automatic tensioner, indicating far less play. It's usually a small adjustment of 1/8-1/4 turn of the adjuster bolt (one full turn is about .060" on the M8-1.25 bolt I use) and might only come about every several thousand miles. You also need to be sure to tighten the lock nut adequately. 

One way to check for noise if you have one of those fours or twins with the cam drive in the center is to use a mechanic's stethoscope, like this.  It is also handy to listen for other noises to locate where they are coming from.  I have two slightly loose valves (clearance) in my Zephyr.  I can locate them with the stethoscope I have.  Handy item when you need it.

You'll actually check your valves more often than it will need adjustment. All you do is every so often at the end of your ride let the bike sit there and run while you take off your helmet and listen to see if it's ticking at all. Just don't confuse valve tick from the head with chain ticking from the tensioner area, that's where the mechanic's stethoscope comes into play. It was more for the Zephyr where the drive is in the center of the engine, the outside cam drives are easy to hear.

I bought into the “Kawasaki engines are noisy” with the KLX and ended up several hundred in the hole due to two tensioners going bad.  I got the same comment on the Zephyr, but knew different.  That bike has over 10,000 on the tensioner without any noise so far.  I used the mechanic’s stethoscope on it to listen to the cam drive and heard basically nothing so there is no rattle of a loose chain and no “shushing” of overly tight tension on the slider.  With the drive on the outside like the Concours and my KLX it’s much easier to listen for noise without aid.   

The first Concours owner, who lives near me and has some of the same friends, bought one after bantering back and forth with a dealer.  The dealer said nothing could be done and that his bike was “old technology”.  He called me the day after he picked up the tensioner to tell me how it worked and that I needed to shorten the bolt a bit, which I did, but I still make sure it’s long enough.  That was last fall.  No problems, otherwise I’d hear from him.   

You can bounce it back and forth all you really want, but when a tensioner does quit working you have to make a choice:

Do you do stop-gap resets that may work for a while or may not work at all, while taking a chance of ruining engine parts? 

Do you buy a new $70+ OEM tensioner, buying chain and sliders if needed, taking another chance? 

Do you buy a manual tensioner to replace the failed OEM unit, buying the sliders and cam chain only if necessary?

Well if you have to buy new sliders you have tensioner issues and buying a new OEM tensioner is expensive.  If you go with another OEM unit, will it last?  If you go with a manual tensioner that you or a good mechanic can understand and deal with, keeping tension at a minimum and not having to replace sliders as often since the chains never get overly loose will be the known outcome. 

Many of us went that way.  It is a fix if done soon enough, within a thousand or so miles, that will be permanent and prolong engine life dramatically.  If it doesn’t take away the noise, look elsewhere, because it’s no longer the cam chains.  I spent part of an evening on the phone actually while an Eliminator owner was doing the adjustments.  We found his noise wasn’t totally the cam chain adjustment.  Apparently the pollution control air injection had some gaskets not seated right and making noise.  He now rides a quiet, except for exhaust maybe, Eliminator.  He knows the cam drive is tensioned decently without excess play. 

Your call. 

One thing I want you to understand, after the tensioner is adjusted at full operating temperature, the engine may tick a bit when started up cold.  The reason for the ticking is thermal contraction/expansion of all the engine parts.  When chain tension is set properly at full operating temperatures there is little if any actual tension on the chain so as not to cause premature wear on parts, so when the engine is cold everything has contracted in size and there is a bit of play in the chain for the first few minutes of warm up.  It should be of no concern, because the engines warm up quickly and the play is so small.  It is no where near as bad as the play when an adjuster fails and not all the time as with a failed tensioner.  I want you to understand why, when the engine is cold, there is a small amount of cam chain noise.  Presently my own KLX650 has done over 30,000 miles with this manual set up, the Zephyr is over 10,000 miles without any problems. 

 Mark

 

Copyright © 2009 Krieger Cam Chain Tensioners
Last modified: 08/19/12