Now that I'm faced with a rattle that won't go away at any temperature and a slowly stretching cam chain, I have to ask: what is the failure mechanism of the CCT? Is it that, after the chain stretches a certain amount, the CCT just can't take up any more slack? Or is it that it just fails after X number of miles, due to the spring wearing out?
I ask because this will determine if I need to swap the chain as well when I put in a new CCT. If CCT failure isn't directly related to chain wear, then I can probably get away with just a new CCT. But otherwise, I'll need to swap the chain out too.

Thanks in advance!

 

Not an expert in this matter but I'm not sure if they fail- I think rather the oil dampening bit fills with debris and the unit locks up. Clean it out and you should be good to go. I cleaned mine recently and it still made objectionable noise- I needed a camchain which I installed and all is good now.

 

Someone should correct me if I'm wrong, but as I understand it:
1) Chain stretches through use
2) CCT tensions the chain to prevent the chain from flopping about as it stretches. Much the same way we adjust our drive chain as it stretches, except this happens automatically with the CCT.
3) For some reason, the CCT fails. The chain continues to stretch, but now has nothing to keep the tension. It starts rattling around, creating the noise that us CBR owners are so familiar with.

In your case, my guess is that the CCT failed. Cleaning it didn't make the noise go away because you still have a stretched chain with nothing to tension it. The noise went away when you replaced the chain because the brand new chain has not stretched, and as such isn't rattling. If I'm right, then over time this chain will inevitably stretch too, and since your CCT isn't working, the rattle will come right back.

There is every chance that I am dead wrong on all this! Hope someone who knows more about this than I do can chime in

 

No. My tensioner works very well. It was frozen previously from debris in the dampener. Just need to clean tensioner from time to time. Same thing goes with my spare modified tensioner.

 

Hmm ok, I'm happy to give that a try. To get the tensioner out, I don't need to remove the chain, right?
Also, one thing I'm curious about - why the rattle persist even after you cleaned the tensioner, until you put a new chain in? Do these tensioners just stop working very well once the chain hits a certain level of wear?

 

The chain doesn't stretch through use. It's not held at tension (ie it's always a little slack) and this protects the chain. Picture your drive chain. It's always a little slack, and if it were tense as soon as your rear wheel went over a bump it would snap. Same thing here. They're not designed to absorb shocks at tension - rather you want a bit of slop in the system to prevent catastrophic failure. If your timing chain has stretched than it's an indication of something else - ie CCT failure would result in chain being too loose, not too tight

The CCT is what protects the cam chain by allowing the right amount of slack. bonester is right when he says that the oil chamber can get filled with gunk and that can prevent the hydraulic damper inside the CCT from fully extending. I'd echo his advice to clean it out before assuming that the CCT has failed. If it had failed your timing would be off with the potential for piston to meet valve at high speed. That's a different problem entirely

 

Mine is a little noisy when cold but goes away when she warms up

 

To remove the tensioner you need to remove the valve cover and then the inlet camshaft. Chain stays in the engine. A worn chain will be longer so much so the tensioner cannot tension it futher and it makes noise. The chain doesn't stretch but it wears at every link of the chain- all these small wear or freeplay if you like in the links add up to a longer (probably noisier) chain. I think the Honda design as much as I don't like it seems to have a much longer range of tension in the tensioner than other designs and maybe this is why they chose this unusual tensioner design???

 

Alright! Thanks for the advice thus far - I went ahead and pulled out the cam chain tensioner.


The bit my right hand is holding (the rod-like part) does not move at all. The hinge that pulls the spring does move (being pulled by my left hand), as shown in the video. Not sure where the oil chamber that @tentacleslap and @bonester mention is?

Thanks!

 

Yours looks normal so far. There's not a huge range of motion on the lower pivot. The oil chamber is the lower bowl-shaped section. Per the FSM, to confirm operation you'll want to add oil to the oil chamber and try yanking on it. It should resist jerking motion but allow smooth motion. To clean it out simply give it a blast of solvent and flush with clean oil

I took a video of mine when I had it apart. You might want to watch from 1:30 to 2:15 to see how mine looked for comparison