How could this cam chain tensionser

[dcarver]

Most CCT's I've seen have a locking mechanism to prevent plunger retraction and resultant engine damage.

Here's the one currently installed on my KZ1300

The other side

Apart

Looking into the body, nothing fixates the plunger.

Does this seem like poor engineering? Just a spring and a plunger? The FSM clearly shows a locking ring with ball bearings acting as a one way valve. I don't recall ever replacing this unit, but then again I've had the bike for a long time and now suffer from CRS...

Entire thread here

 

[wfooshee]

Depends on how strong the spring is, I guess. But if it's so strong the chain can't move it far enough to matter, I'd be worried about guide wear . . . .

Um, is there a locking ring with some ball bearings in the crankcase???

 

[FJRBluesman]

Don - You have far larger issues then to worry about a CCT. :dribble:

 

[escapefjrtist]

The tensioner is mounted on the slack side of the chain. My take on this -- the spring needs to be strong enough to limit movement on the slack side, not to keep the chain fiddle string tight. I would bet your bigger concern is the badly worn cam chain idler. Once that is replaced / repaired the tensioner will function as designed.

Just my $.02

--G

 

[Geezer]

It is always interesting to look at the way things are designed and figure out how they work, but the bottom line is that if this is the stock CCT for that engine and there is no history of CCT failure for that model and no indication that the CCT is not being held in place in that particular engine then it must work.

 

[Fred W]

The tensioner is mounted on the slack side of the chain. My take on this -- the spring needs to be strong enough to limit movement on the slack side, not to keep the chain fiddle string tight. I would bet your bigger concern is the badly worn cam chain idler. Once that is replaced / repaired the tensioner will function as designed.

I disagree.

Even as the tensioner is on the slack side of the cam chain, when an intake cam goes "over center" it will have the effect of pulling up on the slack side chain faster than the chain is being drawn down by the crank sprocket. Then there is also the possibility that the engine may be turned in reverse when not running. If the tensioner doesn't have enough resistance and it compresses under that chain pull it can allow excessive slack elsewhere in the chain and you'd start to skip teeth. That is why the majority of CCTs have a ratcheting mechanism built in to prevent compression of the tensioner once extended.

There really is never a time (except when servicing) that you would want the CCT to compress once it has extended to take up the slack.

The FJR CCT doesn't have any such ratcheting mechanism (either), but due to the spiral ramp of the helical screw type actuator, it is much harder to compress an already extended tensioner than the pressure that the plunger exerts on the chain.

This CCT is a compression spring acting directly upon the cam chain with no other mechanical advantage. I would say that either you are missing the locking/ratcheting mechanism (if one ever existed) or it is of an extremely poor design.

PS - Geezer posted while I was replying, but I disagree with him too. We are not sure that this CCT is the stock one, nor if it is complete. Also, it seems that this model does have a history of CCT failures, probably larger than the FJRs.

 

[dcarver]

This CCT is a compression spring acting directly upon the cam chain with no other mechanical advantage. I would say that either you are missing the locking/ratcheting mechanism (if one ever existed) or it is of an extremely poor design.

PS - Geezer posted while I was replying, but I disagree with him too. We are not sure that this CCT is the stock one, nor if it is complete. Also, it seems that this model does have a history of CCT failures, probably larger than the FJRs.

The CCT pictured in the FSM is much different looking than what I have. The one in the FSM has locking ball arrangement. And YES, many a KZ1300 engine has been destroyed by a the POS OEM CCT. I've posted on several KZ sites and will let everyone know what I find out. I AM looking forward to the correct APE manual tensionser..
Thanks for posting guys - always a good read.

 

[Fred W]

The CCT pictured in the FSM is much different looking than what I have. The one in the FSM has locking ball arrangement. And YES, many a KZ1300 engine has been destroyed by a the POS OEM CCT. I've posted on several KZ sites and will let everyone know what I find out. I AM looking forward to the correct APE manual tensionser..

Thanks for posting guys - always a good read.

Hmmm... You may have already committed to buying the manual tensioner, but why not go with the correct, self locking auto tensioner if one exists? Or is that the one that the failures were reported on?

Personally, I'm not a huge fan of manually adjusted cam chain tensioners. Just one more place where a small human error can result in a catastrophic outcome. YMMV

 

[wmadoty]

I could be mistaken as it has been a very long time since I made a cam chain adjustment, but I thin my XS-1100 had a similar designed CCT to the one you displayed. If I remember correctly, the bolt on the housing locked the plunger. To adjust you put some tension in the direction of engine rotation and loosened the plunger bolt. It it was badly out of adjustment you would hear it click as the spring pushed the plunger into the slack. Then while keeping a little pressure on the crank in the direction of engine rotation you tightened the release bolt.

Is it possible yours works this way?

 

[dcarver]

Hmmm... You may have already committed to buying the manual tensioner, but why not go with the correct, self locking auto tensioner if one exists? Or is that the one that the failures were reported on?

Personally, I'm not a huge fan of manually adjusted cam chain tensioners. Just one more place where a small human error can result in a catastrophic outcome. YMMV

Good question. A stock KZ1300 superseded part number doesn't exist. A similar model, from a KZ100 does fit, but it has greater spring pressure; some have reported excessive wearing of the cam chain idler gear. Since my idler is marginal, I decided to use the manual CCT.

I could be mistaken as it has been a very long time since I made a cam chain adjustment, but I thin my XS-1100 had a similar designed CCT to the one you displayed. If I remember correctly, the bolt on the housing locked the plunger. To adjust you put some tension in the direction of engine rotation and loosened the plunger bolt. It it was badly out of adjustment you would hear it click as the spring pushed the plunger into the slack. Then while keeping a little pressure on the crank in the direction of engine rotation you tightened the release bolt.

Is it possible yours works this way?

No, the bolt only keeps the plunger from fully extending, e.g. it keeps it captive within the distance of the slotted area.
Sooo then...

Sent an email to David Ewing, of KZ1300.com, his reply...

That's not the CCT tensioner. Look to the right of that tensioner about 5 inches. This tensioner is for the water pump drive and we don't have any problems with it.

ARRGH! I pulled the wrong chain tensioner!

 

[wmadoty]

Glad you got it sorted DCarver and sorry I could not be of some assistance. I would have never thought that it would have more than one of those little buggers.

 

[wfooshee]

Hey, at least nobody here knew that and pasted you for it!

OTOH, where you pulled it from vs. where the chains are . . . . coulda been a clue. I'll not drag out your own picture to point out the distance between those two chains. I'll just let that rest, and never bring it up again. Ever. Just this once.

 

[dcarver]

Glad you got it sorted DCarver and sorry I could not be of some assistance. I would have never thought that it would have more than one of those little buggers.

Yeah, this motor has lots of chains.. me thinks it wants to be a Harley?

Hey, at least nobody here knew that and pasted you for it!

OTOH, where you pulled it from vs. where the chains are . . . . coulda been a clue. I'll not drag out your own picture to point out the distance between those two chains. I'll just let that rest, and never bring it up again. Ever. Just this once.

Actually, without looking at the bike, I'm still somewhat mystified. I saw the two tensioners, and think I chose the one centrally located. It just made sense to me the cam chain would run up the center of the block.. I'm still not convinced... and it's dark and cold outside which overwhelms my curiosity..

..and please DO make fun of me, I like it!