CCTs Again

[oldbikeman]

I hate hearing of folks pride and joy going bang so I'll throw in my two penny s worth
Because of the length of the cam chain and cylinder/head a ratchet type or locking adjuster
is not advisable.Honda's own does work OK until the pressure spring fails or the unit partially seizes causing an over tight chain.This simplest cure I can think of is to remove the cap on the end of the adjuster.Then take a small screw driver and engage it in the slot in the back.Then turn it clockwise only a quarter turn to check the spring and that it's not seized.
Now find a nut and bolt the same thread as the end cap also a flat washer and a fibre washer .Assemble and gently thread into the adjuster until you feel it touch.Now back it out a full turn and a half.tighten up the locknut.Now if your adjuster fails you,ll know about it but you won't have a bust motor.
CheersfromPAUL

[tony.mon]

Because of the length of the cam chain and cylinder/head a ratchet type or locking adjuster
is not advisable.

Interesting comment, why is that, Paul?

If you mean over tight can put excessive pressure on the lower half of the head/cam sprocket side plain journal, I agree.
But then they shouldn't be set over tight.

Over loose would lead to rattling, but the bolt would have to unscrew 15mm+ to be so slack as to permit cam chain to override the sprocket teeth, and it would certainly be audible long before then.
The cam timing would go out a few degrees, but by my own measurements building an engine with High-Comp's recently there's over 3mm of clearance between piston crown and valves, even with High-Comps, and therefore even more with standard pistons.
This means that even though the valve timing would drift slightly if the chain were loose, it would be nowhere near allowing the piston to hit the valves.

The only other thing I could imagine you'd mean is the difference in the coefficient of expansion between the (largely) aluminium cylinders and the steel cam chain, effectively tightening the chain as the engine gets hotter. But I would always suggest setting or checking the tension when the engine's hot, to allow for this.
When cold that would lead to a tiny bit of slack, but less than 1mm so not important.

I suppose I'd best sum up by saying that I'd rather fit manuals and have no fear that spring breakage would be able to affect my engine ever again- especially having had one go before! As long as it's only bent valves it's not too bad, but if a valve drops off it's goodbye engine.

(did I mention I had a couple of spare engines, by the way?)

[oldbikeman]

OK right
If you tensioned the chain while cold unless you got the slack right it would be very different when hot.The VTR has the longest chain of any bike I know of and no cam sprockets are ever perfect and no chain ever wears even that's why SPs have gears instead.A constant tension device is Honda's answer to an unideal situation.Using a simple bolt backed off allows it to function and gives a measure of reliability.This should stop the spring from being thrashed about when engine speeds change quickly.
Paul

[oldbikeman]

Should Mention
If I was stripping the motor often I'd definitely use manual CCTs .

[sirch345]

Using a simple bolt backed off allows it to function and gives a measure of reliability.This should stop the spring from being thrashed about when engine speeds change quickly.
Paul

Now find a nut and bolt the same thread as the end cap also a flat washer and a fibre washer .Assemble and gently thread into the adjuster until you feel it touch.Now back it out a full turn and a half.tighten up the locknut.Now if your adjuster fails you,ll know about it but you won't have a bust motor.
CheersfromPAUL

Paul, no, that won't work (that is if I'm understanding correctly what you are saying). The screw/worm with the slot in it only turns when the tension alters, so consequently it won't rest up against your bolt situated one and a half turns back.

The screw/worm is not in any of those threads that the 6mm end bolts screws into, the function of the screw/worm is purely in a circular motion only.

If you want the CCT to function in the normal way as Mr Honda intended then I would suggest doing the stopper mod.

Chris.

[AMCQ46]

Paul,
I am with you half way here.............I personaly think the best solution is to have the spring loaded adjuster that Honda planned, and then fit some fail safe device to stop the plunger retracting if the spring fails.

BUT

I am with Chris on the technical merit of your version of the fail safe device, you have tried to put an axial position limit against a part that only rotates [no axial motion], so although your idea is good the implimentation is flawed.

The stopper mod is the same concept but fitted between the parts that do move axialy...........only problem is you have to strp down the CCT to fit the stopper...........but once done you have best of both worlds

[oldbikeman]

Oh Ek!
I had the idea that the screw moved back and forth with the plunger so no it won,t work and locking the screw is not the answer either.How about using a simple spring loaded plunger type except putting a telescopic tube around it and itself attached to a ratchet ,blocked with a shock absorbing stopper at the end .This would allow axial play and self adjustment.
Gotitwrongpaul

[AMCQ46]

Paul,
have a look in the workshop section on the CCT stopper thread, there are pictures of the solution that Chris and others came up with. and they tested it with a failed spring, so I am more than happy to run my bike with this failsafe.

it is pretty easy to do

[oldbikeman]

Another Idea take a look
http://img.villagephotos.com/p/2010-11/ ... %20CCT.jpg

[oldbikeman]

Yes this idea works as I explained but I had the screw function wrong way round,only seen photos(Dope).Any how I don't understand this quote .Surely both tensioners are on the non pulling side?

The difference of 1/4 turn for the rear and 1/2 a turn for the front CCT is due to the fact that one CCT tightens up and the other slackens off when in use. So basically I've allowed 1/4 of a turn free play, allowing for expanding/shrinking of the different metals etc as they get hot when in use.)

[sirch345]

Any how I don't understand this quote .Surely both tensioners are on the non pulling side?

The difference of 1/4 turn for the rear and 1/2 a turn for the front CCT is due to the fact that one CCT tightens up and the other slackens off when in use. So basically I've allowed 1/4 of a turn free play, allowing for expanding/shrinking of the different metals etc as they get hot when in use.)

Paul,
I'm glad to see you are doing your home work

I too thought both CCT's would work in the same way, after all like you say they are both taking up the slack of the cam chain on the non-pulling side.

In my search (many many hours spent doing this) for a better alternative to the standard CCT's, and the fact that I didn't just want to take it for granted that the rear CCT would operate in exactly the same way as the front one does (I tested the front one first), I carried out tests on the rear tensioner out on the open road which is in true operating conditions. If I had a dyno in the w/shop I would have most likely used that instead.

Here are the results from my tests:-
Basically the front CCT slackens off approx. 1/4 of a full turn and the rear CCT tightens up as the rev's rise.

The only explanation I can give for the operating differences between the two CCT's is the fact that the front CCT takes up the slack on the top of the chain run, whereas the rear CCT takes up the slack on the bottom of the chain run, due to the V twin engine configuration. As you say both CCT's are operating on the non-pulling side of the cam chains.

HTH,

Chris.