Cam chain gap on sprocket

[steve68steve]

[As noted in my post when this thread became it's own, this thread has been split from Zepfan finding a piece of metal in his engine in the thread called "Cold Start / Chain Tensioner / Busted Motor JUNK TENERE ??" (http://www.yamahasupertenere.com/index.php?topic=23468.0) If something seems a bit disjointed, it's because that thread got to the point where people were trying to respond in single posts to both Zepfan and Steve68Steve. - Checkswrecks]


Now for the hi-jack. I'm a day or two ahead of you, so you'll be looking at this on your bike soon.


Look at this pic of my intake cam sprocket.

There are 3 things that bother me:
1. The gap between the peaks and troughs - it looks like the chain is not fully meshed with the sprocket. I don't know how much gap is normal.
2. The small gap at the pitch diameter - the manual says "1/4 tooth". How the heck are you supposed to measure THAT? I'm well below 1/4, but still...
3. The rainbow of colored metal in the center of the pic. Is this a vestige of heat treating and normal, or were these sprockets cooked in operation?


Now, look at how little adjustment is left in my brandy-new Graves manual CCT:

This pic makes me question whether my CCT was really bad or whether I just needed a new chain and sprockets. Is this normal with 36k mi on the bike? In other words, does the amount of wear and adjustment left translate to another 100k mi or another 20k mi. If the former, I'm buttoning it back up. If the latter, I'm offline again waiting for a new chain and sprockets.


Sorry for hi-jack, Zepfan. Hopefully this info will help you... altho at 80k mi and how much money you spent on parts, maybe you're already out in front of this.

 

[~TABASCO~]

The gap normal until the CCT or MCCT are installed and the motor is manually turned over. There then should be no gap and the chain tight. The rainbow color is normal. The graves looks about right and normal. I would say there is no way the chain is worn out at 35K.
Everything looks normal but the gap in the chain. Just tighten up the graves properly, manually turn over the motor, double check everything, and you are good to go.

 

[steve68steve]

The gap normal until the CCT or MCCT are installed and the motor is manually turned over. There then should be no gap and the chain tight. The rainbow color is normal. The graves looks about right and normal. I would say there is no way the chain is worn out at 35K.
Everything looks normal but the gap in the chain. Just tighten up the graves properly, manually turn over the motor, double check everything, and you are good to go.

Thanks. That pic is after turning the engine over a half dozen times. The mCCT is adjusted in, as shown, the chain is snug.

Sent from my SCH-I545 using Tapatalk

 

[eemsreno]

If you already have tension on the chain then there is major problems going on here.

The blue discoloring is normal

I also run a Graves CCT and mine isn't that far used up with over 46,000 miles on the new chain I put in at 122,000 miles.

Here it is with a new chain at 122,000 miles.

Here at 168,000

 

[~TABASCO~]

The chunk of metal is not good.


The chain/sprocket: I've had this happen to me several times. Because this is a 270* there is always pressure on one of the cams. For me, this is what it looks like just before it skips teeth and I have to re set the cams. I've caught it several times before it ever skipped on the reinstallation of the cams after a valve adjustment. I believe the service manual has a page that shows how to use a special tool or a crescent wrench to unload the pressure off the cam, from the valve spring and put the chain back down on the teeth of the sprocket. It takes about 2 seconds to re set the chain on the sprocket.

I will admit that I've not had time to read every word in this post. Just posting info that I might have encountered while working on a hundred of these.

 

[eemsreno]

Thanks. That pic is after turning the engine over a half dozen times. The mCCT is adjusted in, as shown, the chain is snug.

Sent from my SCH-I545 using Tapatalk

Sorry but this is NOT normal and not right. It should not look like this after your above statement.

 

[Zepfan]

Thanks Steve,
Yes resetting the cct is really hard. I haven't succeeded yet. I hope the new one comes pre cocked. Practicing on my old one

The broken bit is not from my cct.

 

[RonH]

The new tensioner comes retracted, but being one that doesn't trust new parts I had to make sure mine properly extended before install on my 2012. Retracting takes some practice. I like the tensioner design. I agree something not right on Steve's bike. Maybe something not right from back at the initial service before failure when abnormal noise was heard still there. No way that much play between the teeth and chain will not jump timing again.

 

[steve68steve]

The chain/sprocket: I've had this happen to me several times. Because this is a 270* there is always pressure on one of the cams. For me, this is what it looks like just before it skips teeth and I have to re set the cams. I've caught it several times before it ever skipped on the reinstallation of the cams after a valve adjustment. I believe the service manual has a page that shows how to use a special tool or a crescent wrench to unload the pressure off the cam, from the valve spring and put the chain back down on the teeth of the sprocket. It takes about 2 seconds to re set the chain on the sprocket.

Thanks!!

I tried to "unload" the chain last night and it seemed harder to crank the intake camshaft than I remembered.

Woke up this am and thought: "duh. The CCT is in". Will try backing off the CCT to gain enough slack to de-tension and reset the chain.

If it works, that means I must have caused the timing slip with my chain install - meaning maybe the stock CCT was/is fine. If not, I'm back to head scratching and will probably buy a new chain.

Since you've seen it a hundred times, does the shape of my sprocket teeth look right? Do they look worn or is that how they're supposed to look?

Live and learn.



Sent from my SCH-I545 using Tapatalk

 

[mebgardner]

Thanks!!

I tried to "unload" the chain last night and it seemed harder to crank the intake camshaft than I remembered.

Woke up this am and thought: "duh. The CCT is in". Will try backing off the CCT to gain enough slack to de-tension and reset the chain.

If it works, that means I must have caused the timing slip with my chain install - meaning maybe the stock CCT was/is fine. If not, I'm back to head scratching and will probably buy a new chain.

Since you've seen it a hundred times, does the shape of my sprocket teeth look right? Do they look worn or is that how they're supposed to look?

Live and learn.



Sent from my SCH-I545 using Tapatalk

Steve:

I don't think loosening the mCCT that you've got mostly cranked in, is such a good idea at this point.

At that mostly cranked in position that you've shown in previous pictures, and now the indication in that same set, is the intake cam is getting ready to jump teeth.

You loosen that mCCT, and it may be sure to jump, then.

The method given in the service manual, to tighten up the chain onto the cam teeth, assumes the OEM "automatic" CCT is in place. That's not your case.

I'm wondering here if the "right thing" to do, is to crank don harder on the mCCT, and see if the chain will set / "squat" further onto the intake cam teeth.

If it were me, I would not spin the crank any more until I had an answer about what to do next. Because, if it skips, you're done. You're going in...

 

[mebgardner]

Now for the hi-jack. I'm a day or two ahead of you, so you'll be looking at this on your bike soon.


Look at this pic of my intake cam sprocket.

There are 3 things that bother me:
1. The gap between the peaks and troughs - it looks like the chain is not fully meshed with the sprocket. I don't know how much gap is normal.
2. The small gap at the pitch diameter - the manual says "1/4 tooth". How the heck are you supposed to measure THAT? I'm well below 1/4, but still...
3. The rainbow of colored metal in the center of the pic. Is this a vestige of heat treating and normal, or were these sprockets cooked in operation?


Now, look at how little adjustment is left in my brandy-new Graves manual CCT:

This pic makes me question whether my CCT was really bad or whether I just needed a new chain and sprockets. Is this normal with 36k mi on the bike? In other words, does the amount of wear and adjustment left translate to another 100k mi or another 20k mi. If the former, I'm buttoning it back up. If the latter, I'm offline again waiting for a new chain and sprockets.


Sorry for hi-jack, Zepfan. Hopefully this info will help you... altho at 80k mi and how much money you spent on parts, maybe you're already out in front of this.

I want to note here, for those of us thinking to swap to the manual CCT.

Take a look at these pictures. This is the fire we're considering playing with.

As long as there's no chain rattle noise, we think everything is fine, we're all good.

I think these pictures put the lie to that assumption.

This cycle has a long timing chain, longer than most. We assume that "no rattle" noise means "tight enough".

But these pictures leave me wondering if that assumption is really true?

I guess there's no way to know without taking off the PITA valve cover.

Yeah, I'm still mullin' this "upgrade" to an mCCT. I'm definitely on the fence about it, now. It helps that I have a late model spec OEM CCT. And No Noise.

When that cover does come off on my cycle, this is gonna be the first thing I'm looking at.

 

[steve68steve]

Steve:

I don't think loosening the mCCT that you've got mostly cranked in, is such a good idea at this point.

At that mostly cranked in position that you've shown in previous pictures, and now the indication in that same set, is the intake cam is getting ready to jump teeth.

You loosen that mCCT, and it may be sure to jump, then.

The method given in the service manual, to tighten up the chain onto the cam teeth, assumes the OEM "automatic" CCT is in place. That's not your case.

I'm wondering here if the "right thing" to do, is to crank don harder on the mCCT, and see if the chain will set / "squat" further onto the intake cam teeth.

If it were me, I would not spin the crank any more until I had an answer about what to do next. Because, if it skips, you're done. You're going in...

Clarity: the pics I posted are with the engine out of the bike. I have zero fear of it skipping time, because I'm looking right at it and it's no great shakes to re-set it.
I want it well-seated and confidence it's right before I put it all back together, tho.

EDIT for even more clarity: the chain in these pics is not "as discovered". Both camshafts have been out and I've re-set the timing, which is perfect. The chain doesn't appear to be well-seated on the sprocket, but has traveled around many revolutions cranked over by hand.
My concern is that the sprocket teeth or chain are worn to the point of needing replacement (I doubt this, and hope it's just under too much tension to seat).


Point: don't assume your chain looks like based on the position of a manual CCT or mileage, or whatever.

 

[RonH]

I don't think anyone has ever seen worn teeth on a camshaft sprocket, and as someone else pointed out somewhere in some thread recently, the hyvo chain should be good for 200,000 miles. Of course always the rare exception possible. To me the factory tensioner is perfect, it extends the instant any chain play happens, and can't go back reverse. It seems foolproof and reliable, but apparently not the case, at least on the older part number.

 

[scott123007]

Clarity: the pics I posted are with the engine out of the bike. I have zero fear of it skipping time, because I'm looking right at it and it's no great shakes to re-set it.
I want it well-seated and confidence it's right before I put it all back together, tho.

EDIT for even more clarity: the chain in these pics is not "as discovered". Both camshafts have been out and I've re-set the timing, which is perfect. The chain doesn't appear to be well-seated on the sprocket, but has traveled around many revolutions cranked over by hand.
My concern is that the sprocket teeth or chain are worn to the point of needing replacement (I doubt this, and hope it's just under too much tension to seat).


Point: don't assume your chain looks like based on the position of a manual CCT or mileage, or whatever.

I'm going to jump in because of this post above. My point would have been moot had you not mentioned removal of your cams but since you did...

A couple of years ago there was an issue where a cam chain was not positioned properly on the guide (I think it was jaeger22) after he adjusted the valves. He rode the bike for about 50 miles before it grenaded . You might want to look closely down the cam chain tunnel and make sure the chain is where it is supposed to be. If you can't tell, remove the intake cam again and check. That could explain the poor seating issue of the chain, and, why the tensioner bolt appears to be adjusted further in than it should be.

If it is any consolation, the cam sprocket shows absolutely no signs of wear, so that means the chain is still in good shape.

 

[steve68steve]

Since I started this as a hi-jack, I'll keep all the info together - another (hopefully second last) edit about the timing chain:

I tried the suggestion to release chain tension on the intake sprocket by cranking it forward a bit. The chain still didn't seat. I turned the engine thru some random amount and heard a "click" from the chain, so I brought it back to the timing marks, which were still perfect.

Perplexed, I turned the engine over a few more times and there's a point in the cycle at which the chain "clicks" on every revolution. At this point it does seem seated a little better. I pushed down on the section of chain which spans the two camshaft sprockets and it deflected a lot... like maybe 1/4 - 1/2". There is NO slack at the timing point.

Then I ran the engine around a slowly checking the tension on that top section of the chain and it varies a lot thru the cycle. Since the distance between the sprockets is fixed, I take this to mean that not only is the chain stretched (worn), it's not uniformly so. The "click" happens when the spot of low tension meets the intake sprocket - the chain settles deeper into the sprocket at that point - I assume this movement is what causes the sound. I wonder if this "click" once per revolution at 3000rpm is what I was hearing.


[font=verdana, arial, helvetica, sans-serif]Bottom line, it's getting a new chain. Hopefully the last hi-jack here will be: "yep, new chain, all's well."[/font]

 

[OldRider]

Since I started this as a hi-jack, I'll keep all the info together - another (hopefully second last) edit about the timing chain:

I tried the suggestion to release chain tension on the intake sprocket by cranking it forward a bit. The chain still didn't seat. I turned the engine thru some random amount and heard a "click" from the chain, so I brought it back to the timing marks, which were still perfect.

Perplexed, I turned the engine over a few more times and there's a point in the cycle at which the chain "clicks" on every revolution. At this point it does seem seated a little better. I pushed down on the section of chain which spans the two camshaft sprockets and it deflected a lot... like maybe 1/4 - 1/2". There is NO slack at the timing point.

Then I ran the engine around a slowly checking the tension on that top section of the chain and it varies a lot thru the cycle. Since the distance between the sprockets is fixed, I take this to mean that not only is the chain stretched (worn), it's not uniformly so. The "click" happens when the spot of low tension meets the intake sprocket - the chain settles deeper into the sprocket at that point - I assume this movement is what causes the sound. I wonder if this "click" once per revolution at 3000rpm is what I was hearing.


[font=verdana, arial, helvetica, sans-serif]Bottom line, it's getting a new chain. Hopefully the last hi-jack here will be: "yep, new chain, all's well."[/font]

In my opinion there's no way you wore out a HYVO chain at 36K. The chain isn't fitting down in the sprocket teeth because it has too much slack in it, that's also the reason you hear that click when it cams over. Go back and start from the begining. Pull the clutch cover and check the chain guide and tensioner and pull the CCT and give it a look over. There's a reason you have slack in the chain. Like RonH said above, it's almost unheard of for the sprockets to wear out. The HYVO chain is designed to sit down in the sprocket teeth and distribute the force over a larger area than a typical roller chain. My two cents worth anyway.

 

[scott123007]

This thread is going to hell in a hand basket, fast. It has been merged with two different people with two different problems so it's getting more confusing to follow.

Stevestyeve, I said my part above and Oldrider has confirmed it. Your chain is NOT the problem. If you are not familiar with how cams load the chain (especially ones with a 270 degree firing order) then you "might" be biting off a little more than you can chew with trying to diagnose this problem. There are positions during the rotation that the cams are fighting against the chain, and others where there is no conflict at all. If you can put tension on the chain by turning the crankshaft and at the same time tighten the manual tensioner, there should be a point that it will take all that slack out assuming something else is not amiss. Like I said earlier and as Oldrider has suggested also, your best bet is to take the tensioner back out as well as the cams, and start over. Something is not lined up right or adjusted right, but it is not a worn out chain.

Ramseybella, I think it has already been determined that that broken piece is not part of the valve train from the OP's engine.

 

[WJBertrand]

I'm going to jump in because of this post above. My point would have been moot had you not mentioned removal of your cams but since you did...

A couple of years ago there was an issue where a cam chain was not positioned properly on the guide (I think it was jaeger22) after he adjusted the valves. He rode the bike for about 50 miles before it grenaded . You might want to look closely down the cam chain tunnel and make sure the chain is where it is supposed to be. If you can't tell, remove the intake cam again and check. That could explain the poor seating issue of the chain, and, why the tensioner bolt appears to be adjusted further in than it should be.

If it is any consolation, the cam sprocket shows absolutely no signs of wear, so that means the chain is still in good shape.

IIRC, in the above case the plunger somehow missed the guide and was pressing directly against the chain instead. I suppose if that can happen, perhaps the tensioner plunger could also miss both the guide and the chain?

 

[Checkswrecks]

[This is where this thread has been split from Zepfan finding a piece of metal in his engine in the thread called "Cold Start / Chain Tensioner / Busted Motor JUNK TENERE ??[/size]" (http://www.yamahasupertenere.com/index.php?topic=23468.0) If something seems a bit disjointed, it's because that thread got to the point where people were trying to respond in single posts to both Zepfan and Steve68Steve. - Checkswrecks]

 

[Checkswrecks]

Steve - There are two theories as to what you have and a fairly easy way to see which is right. Your theory (#1) is that the chain locally stretched, leading to the gap at one position and the noise. Theory #2 is that the chain is fine, what you are seeing is because of how the cam sprockets spring-load the chain as it goes around.


Since the engine's on a bench and you can do this fairly easily, put a paint mark on the link which seems to have the stretch or slack. Then re-orient the chain so that link is at least a few inches away in travel. You should be able to easily see if the paint mark is still where there seems to be stretch or slack.