CCT/rattles

Checked front valve clearances today after sorting the rear last week. All in spec and lovely. While the cover was off I decided to switch the CCT with one from the old engine which was working fine, as the one on the front cyl was ticking like a typewriter a little at idle. Went nice and smooth, timing still fine etc. Put everything back together again, started the bike...and it rattles like crazy. Stopped the bike, double-checked the timing, put the old CCT back in in case the one I'd put in was buggered. Still ticking like crazy.

Any thoughts other than "All your CCT are belong to rust"? Bonus points if it's not "your engine's screwed again".

[5hort5]

pass but do you want to try one of my spares m8?

Investigate that its not something just sort of tapping against anything. Is the timing chain too slack? I remember a post by YC a while back asking about the acceptable slack in a cam chain.

Is the cam timing correct?

[Spanner Man]

Good morning all.


Assuming the camchain is itself ok, it sounds like you have a brace of dodgy tensioners.
If it's a Curvy you have, the dreaded spiral type tensioners can fail after removal & re-fitting. This, I suspect, is due to the fact that one has to wind them in before installing them.


Cheers.

Marvellous. I'll try the last CCT in the garage and after that I'll give up and grab one from somewhere else.

Cheers!

Here's a video of what's going on.

When I went to take out the other CCT, I was a little concerned, as it didn't spring out under tension when removing the bolts. It also lifted out quite neatly, no pressure from the tensioner at all. So I took the cover off, put the tensioner back in and this is the result.

The chain's got a fair bit of free play between the cams. It's nowhere near enough to lift off the cams (as shown by trying to pull them off the intake cam, it doesn't come away from any of the teeth at all), but it's clearly enough to slap against the chain guide, making the rattling noise.

I took the tensioner back out again, pushed the chain between the cams to raise the blade and put my finger down the CCT hole. I could feel wear on the CCT blade, so I'm assuming that the blade's knackered.

SO.

1) Is it safe to run the bike like this short-term, as I'm going to need it again as of Monday, 5 mile trips to/from work, ridden gently due to traffic.

2) How easy is it to replace CCT blades? I've got one poking out the spare engine, and it looks like the rotor needs to come off to get to it. Is this right?

3) Is there any way of using a longer tensioner (a manual one, for example), or is the K3 plunger any longer?

[Spanner Man]

Good afternoon all.


That chain doesn't look too bad, most bikes will have a little up & down play in the chain between the camshaft sprockets.

Assuming your bike is a Curvy, the tensioner should extend considerably when removed. Have you tried leaving the tensioner fully extended, & offering it up to the engine to see if the tip of the tensioner touches the tensioner blade, before the body of it is up against the engine?
If the tensioner goes all the way in to the mounting flange with no resistance, the blade has probably had it.
From memory you have to remove the rotor to get the guide out.

Pointys have a ratchet tensioner, I've never tried fitting one to ma Curvy. There are manual tensioners available. APE Billet ones methinks.

Cheers.

If you take the tensioner out, then push the cam-chain down between the sprockets to force the blade up, and then put the tensioner in and push down, you can see that it's all working. If you push the blade in as far as it will go and then put the tensioner in, there's absolutely no resistance on the tensioner at all until it gets to 2-3mm away from the engine...so it *is* keeping tension on the chain, but not really enough. When the engine's running you can hear the cam-chain tapping against the guard, which is why I tore it down because I didn't like the sound.

Looking in ye olde Haynes manual, it says you need to take the cylinder-head off to replace the blade. Is there any way around this? I could probably get the rotor etc. off by myself, but there's no way I'm taking the head off - wouldn't be confident and don't really have the tools. I've got a spare tensioner blade now, though - took it off the rear cylinder of the dead engine since that one's really easy to get to.

Will the APE manual tensioner reach in further than the stock ones? It only needs another 2-3mm probably to get it to the correct tension.

[Spanner Man]

Good afternoon all.


I've only removed the tensioner blade when doing a full engine strip. I've not tried doing it with the top end in situ.
Theoretically it should be possible, you'll still have to remove the rotor to access the blade mounting bolt.

An APE tensioner would have more reach than a standard one. However, if the guide is worn to excess, putting extra tension on it may cause it to snap. With potentially expensive consequences.


Cheers.

I've got an update on this, and pictures of the problem. Will post it up tonight so you can all enjoy...