Got defeated this weekend

[Crazcnuk]

I am not....

I've screwed the top end up just changing the cct.

[thewiz]

Understood, Craz ..

I had one close call where it jumped a tooth or two, IIRC, I think I had the bike on the sidestand as there was no center stand on it .... that was my first mistake ...but I always have carefully turned the motor over a couple revs with a wrench before hittin' the button ... that time it only turned maybe 90 degrees before 'clunking' to a stop. THEN I pulled the cam cover and cams and put it back together correctly. I was very lucky ....

[Larrym]

4 leaf clover??

It seems that some owners have R+R'd the CCT and two categories emerged: those who have jumped a tooth and those who have not. (Note: the consequences of jumping that tooth and afterwards starting the engine are a real bear....) I knew this as I've read Crazcnuk's thread about his performance/mileage problems. Again, he did what he was 'sposed to do but got bit. (Ouch! Just reading his thread hurt.)

Tod, you may have done the CCT R+R lots of times and had no problems. I'm sure that you do turn the engine by hand and check it before actually running the motor. But there is a principle at work here that I feel needs to be stated so we can all understand and use it to our benefit.

It's called the Beysian Principle and it comes from "game theory". Just consider this question:

If you had a two-headed coin and you tossed it 9 times and each time it came up heads, what are the odds that it will come up heads on the tenth toss??

This Monk in a monastery figured out a long time ago that most people would say that the odds of the coin coming up heads on the tenth toss are really high, almost a certainty. Most people would "bet the farm" that the coin would land heads up. This is the way people behave and think.

But the Monk knew that the actual odds on that toss, and on every toss before that actually, was a 50/50 shot. Each time the coin is tossed it can land either heads up or show tails when it lands. Facts is facts but then again people believe that the coin almost has to land heads up. This is the Monk's principle.

So no matter how many times someone has R+R'd a CCT and had no problems (without removing the valve cover and checking, of course...) the odds really are 50/50 each and every time that it is done. The chain may/may not jump a tooth. That's why the manual says to turn the engine by hand and if there is any binding to stop and go back through the "steps" again. Again, I say the odds of my chain jumping a tooth are 50/50 if I remove and replace the CCT and follow the standard operating procedures. (That's just not good enough odds for me.)

I'm not averse to removing the valve cover when necessary. It's just that I say the R+R'ing the CCT as currently practiced can be a procedure where this is needed. (Groan...) I've got a parts motor in a partial frame where I am going to "experiment" with this procedure. I'll pull the valve cover off so I can really see what's-a-happening. The goal I have is to see if there is a way to reliably R+R the CCT without jumping a tooth: without removing the valve cover, standing the bike on its front or rear wheel, growing a third arm, or rubbing my lucky rabbit's foot.

I'll post the results.

[TopCatGr58]

Hey Larry,

The third hand is available as a bungy chord, here's my just thought of technique, doesn't require removing the cam.

Pull the valve cover, loosen the cct plunger and locking bolt after you've rotated the engine a few CW turns and are at the "C" mark. Attach a bungy to the cam chain inbetween the intake and exhaust cams. Then using a wrench rotate the exhaust cam CW as the bungy takes up the resultant slack. Once you feel that the cam can't turn anymore, probably not more than a tooth, then you should be able to remove the CCT, the plunger should have been pushed back into the CCT housing by the rotation of the exhaust cam as you took up the slack between the exhaust cam and the crank sprocket. As you remove the CCT inspect the camchain, and if it looks a little slack, just rotate the exhaust cam a little more to take up the remaining slack, as the bungy pulls up on the slack created between the cams.

R&R the CCT, put it back into position, release the plunger, and slowly rotate the exhaust cam back CCW pulling the slack back down from between the cams and releasing it to the plunger to take up. Temporarily lock the plunger, rotate the engine a few times to again create the max slack at the "C" mark, and reloosen and reset the CCT plunger bolt/lock nut.

You can also then verify the "T" cam chain timing dots at the same time before buttoning everything back up. I think this would be easier than trying to balance/stabilize the bike in the wheelie position on those ramps!?
T.C.

[trbig]

You just don't need all those steps, TC. You surely don't need a bungee. When you rotate the exahust cam CW to take the slack out of the front between it and the crank, (When removing the adjuster) you will only get maybe 2-3 teeth worth of chain. It will make the chain slack between the two cams, but it isn't like it's going to ball up on itself there. If that cradle looking guide wasn't there, you can't even get the chain to bow enough to get even with the gasket surface of the valve cover. The cams don't just spin loosely in there. It takes a wrench or channel-locks to move them. When you re-install the adjuster though, and let it slap the chain, it takes that exhaust cam back to where it needs to be and takes the slack out between the two cams. I suggested moving the crank a tiny bit CW just to make sure you have the slack to the front of the motor and the exhaust cam is getting pulled along with the intake also. The spring on the tensioner will still be holding the proper tension.. so tighten it up at that point.

Larry, what you are suggesting may work for you, but it's not going to be a very viable option for most. Also, though this wheelie technique may work time after time, you're still flipping that monks coin by not having the valve cover off and seeing for sure if you're all in time before firing the bike up. The chain could wiggle a bit after the tensioner is out and grab an extra tooth on the crank, and you'd be in the same boat as if you hadn't gone to all the trouble of supporting your bike in a weird position.


Tod

[Larrym]

TC,

Thanks. I can clearly visualize the steps/technique you wrote. Bungee cord was an obvious, "Duh....didn't think of that" on my part. I'll have your post at hand as I play with my parts motor with the valve cover off.

Tod,

Your absolutely correct about having the valve cover off in order to check whether or not everything is right before I push the starter button. But then again the whole reason why the cover is taken off is because the standard R+R process for the CCT has that "Hit or Miss" quality. Gotta be sure!

I'm just going to look at different ways the CCT swap can be done with an eye for Increasing the odds that the chain won't jump a tooth in the first place. After all, the chain runs vertically between the drive/driven gears and as soon as slack is available it will drop down. I'm considering more options than the "wheelie" position: Bike positioned downhill on a 45 degree incline, and various other minor changes in the procedure. The engine I'll be using has over 40K on it so there should be slack enough to make it fun. I don't know what I'll find until I find it. (Or not....sigh)



I really appreciate the feedback. Thanks to all for taking the time to consider what I've offered here.

LarryM

[Crazcnuk]

You should be able to loosen the adjuster lock then loosen, but don't remove the bolts.

Then if you turn the crank backwards while carefully removing the cct, the slack should sit up top.

Then when you put the cct in, tighten it up, then let the lock go, and then turn the crank forwards.

The tensioner will keep the chain tight while the slack is moved to the front.

Once you've turned the crank about the same amount you went backwards, you can tighten the lockbolt.

[trbig]

By moving the crank backwards, which would just put the slack to the back of the motor.. you aren't going to make the chain push the intake cam forward and make slack there, and you really haven't done anything different except switch sides with the slack. All the slack would still want to go to the bottom of the crank. And with the chain that loose, when you go to try to turn it back, there's a good chance of skipping a tooth, or like before, grabbing a wrong link in the chain.

Of course.. all this of this is meaningless if you were to simply do a cam chain adjustment correctly.. per the book... instead of removing it completely. You won't need to remove the valve cover for a simple adjustment or have to worry about too much slack.


Tod

[oseaghdha]

........................


Of course.. all this of this is meaningless if you were to simply do a cam chain adjustment correctly.. per the book... instead of removing it completely. You won't need to remove the valve cover for a simple adjustment or have to worry about too much slack.


Tod

Ding Ding Ding......We have a Winner!

Seriously, unless you need to remove the tensioner, don't.

[Crazcnuk]

Most of us that remove the cct are doing so to FIX it.

TR: The whole point was to move the slack to the back, just enough to keep tension while you remove the cct.

Rather than just drop the cct out and have all the tension (at the front) drop to the bottom, what i was suggesting is that the crank and cams can keep that tension safe for you by rotating the crank enough to cover for the loss of tension on the tensioner.

You could run into the same problem if your chain is that loose, but you can keep an eye on it during this procedure.

If you look through the cct hole, with a light, you should be able to see that the chain has tension on it. As long as it does, you're fine. If the chain loses tension, then you would have to take off the valve cover and check the alignment of the cams.

It may save having to take the valve cover off, it may not.

[trbig]

what i was suggesting is that the crank and cams can keep that tension safe for you by rotating the crank enough to cover for the loss of tension on the tensioner.

Not understanding what you mean, I guess. Your cams are going to keep the same spacing unless you move your cams. You can't change that by moving the crank alone. So turning your crank, you're either putting the slack to the front or back side of the crank gear.. down where the slack is anyway. and moving a crank around at a time when it has the most chance to jump a tooth.

Tod

[Dan Hodges]

We Have A Winner

Ding Ding Ding......We have a Winner!

Seriously, unless you need to remove the tensioner, don't.

You are correct, just say no to removing the CCT unless it's necessary and it's not necessary to remove it every time you adjust the cam chain for normal scheduled maintenance. If you have to remove it because it is leaking or to retorque the short head stud/nut above it you should remove the valve cover and turn the motor over gently several times by hand after you have reinstalled it to make sure the cams are timed properly before you hit the starter. If you follow the shop manual you should not have a problem, at least I haven't and I've had the cams out of mine more times than I care to remember however the old adage, "what can go wrong will go wrong" is always lurking about when working on the XS and you cannot take anything for granted. This post was becoming another " War And Peace" with no end in sight and I'm gratefull that my boy Tod finally awoke from his speed induced summer slumber and put this subject back in it's locked box.......may it rest in peace.

[Crazcnuk]

When you turn the crankshaft, either way, you have tension between either the front cam and the crank, or the rear cam and the crank.

It has nothing to do with the spacing between the cams.

If you can keep that tension on the chain, the chain won't fall down.

However, if all the slack is at the front, and tension at the back of the crank sprocket, then anything you do at the front has the danger of knocking the chain off of the crank sprocket, thus dropping all the slack under the crank. I believe this danger is greatly reduced if you take the slack to the rear of the crank, while you are doing your repair.


If you can keep the front of the chain tight, while you change the cct, you can't knock it off the crank sprocket, at least not as easily.

[trbig]

It's not the "Doing something" to the chain that causes the problem. The problem is simply having slack down at the crank. Slack at the front... slack at the back.. that is what the problem is. If you have enough slack on the front side of the motor that the crank is grabbing a different link in the chain, you're going to have the same problem no matter which side of the sprocket you happen to put the slack on.


Headed to Iowa for a few days. Everybody have a good weekend.


Tod

[Larrym]

Haven't yet started experimenting with my parts motor as the space I need to do this is taken up by the boxes for my bagger set-up. ( Now waiting for the check from the buyer...)

I say NO! Do not remove the CCT as part of the regular 3K "adjustment" procedure. This thread and my concerns began with a CCT which was leaking and therefore (unless the owner wished to rename his bike "drippy"..) had to be removed, repaired, and replaced.

There are those people who believe that R+R'ing the CCT is an automatic "remove the valve cover" cause belief/experience tells them that without doing so they will be unable to prevent the "tooth-jumping" or deal with the event after it has happened.

There are those people who believe that R+R'ing the CCT is a tricky affair and there just might be a way to do the R+R in a way which may actually prevent the "tooth-jumping" in the first place. This might be less labor and save a valve cover gasket as well.

Do you have to have the valve cover off to know if the chain jumped a tooth? Whether the chain has jumped or not can be checked by turning the crankshaft (CW) and if any binding occurs then the "jump" has been confirmed. This test is done after the CCT R+R'ing.

Like I said at the beginning, I haven't done any "testing" of any procedures yet. I would like to think that Crazcnuk's offering has a chance of working. I mean, what if just as I was about to actually pull the CCT off the engine, I turned the crank CCW just enough to take up the slack on the Front chain and Push the CCT out till it stopped moving?

There head/cylinder isn't perfectly vertical. It tilts forward 10 degrees? 15 degrees? The front and the back of the chain are not equal as far as gravity and tilt. Much easier for the chain slack to drop and "jump" on the front side. At the back the chain might/might not tend to fall forward just a little and the slack to ride the top teeth as the crank is turned slightly CCW to "pop-out" the CCT.

Hmm. I'm gonna try this one. Say, since I haven't had the valve cover off, is there any room to look down inside and see the chain/crank at the rear of the engine? I mean if I had one of those "inspection" cameras? Is there a way to get one of those cameras inside far enough to actually SEE what happens? I believe that the camera needs a 3/4 inch hole/space.

This would go a long way to cluing us in on what is really going on as we turn the engine this way and that. (Plus I've been itching to get one...)

Still waiting to ship those bagger parts boxes..