Is it about time to change the cam chain?

[jetmechmarty]

When you break the chain, you lose that link. You will replace it with another when you link it back together. You do this job with the tensioner removed. The new chain will be very tight. Installing your ACCT will be the last step.

Get yourself a magnet before you do the job in case you have to go fishing.

[scoot]

A good thing to remember is "Never rotate the motor with the cams in, without the adjuster in place!!!!!"
Ever, ever, ever ,ever

Mack, you say rotate the new chain in with adjuster in place if the cams are in.

Marty, you say rotate the new chain in with the adjuster out.

I say, huh?

[bikerphil]

Here is the tech tip on replacing the cam chain....

http://www.xs11.com/xs11-info/tech-tips/maintenance/engine/38-cam-chain.html

Never rotate the motor with the chain or adjuster off, just pull the chain thru with the old one, there is clearance below the crank sprocket to do this.

[mack]

I'm always on

the safe side so thats why I said to remove the cam's and use the crank to guide the chain around. You can do it both ways but when I want to replace a chain thats all I want to do. Having to split the case to retrieve a chain or not so bad but still a pain, replace valves. To each his own on this one. My point was never rotate the engine with the cam's in place and no tensioner. Never.

[scoot]

Thanks for the details. I did not realize you pull the chain around by hand nor that you do it clear of the gear teeth. It seems straight forward enough, but the tech tip warns of getting the chain caught up on the crank gear. I wonder if brushing the chain with synthetic oil or a light machine oil first would keep it from sticking to the gear teeth on installation.

Z1Enterprises.com has the chain for $42, the master link for $3.
Mikesxs.net has the cam chain rivet & breaker tool for $49.

scoot

[scoot]

I had a look around the cam chain as best I could with a boroscope. Nothing stood out as being odd, but then again, the 9mm diameter of the 'scope limited how deep I could get it. So I'm changing the cam chain, as that's what I believe to be the source of the harmonic racket.

I've come to think that the sudden onset of the noise was due to the auto cam chain tensioner simply doing it's job, and it adjusted one more tooth which happened to be the to the final point that the worn, stretched chain can accomodate. And now the noise is due to the tensioner assembly hitting and vibrating against whatever limits it in the engine case.

I read here somewhere that the difference in length between an old stretched chain and a new one is only 4mm. That's surprisingly small. And I run this bike hard, so I can accept that the chain is worn at 60,000 miles.

I'll let you know here if it resolves my noise issue. Thank you all for the help. I am not a mechanic, but I do my own wrenching. I would not be doing this at all without you.

scoot

[jetmechmarty]

scoot,

Consider this. If your chain has stretched beyond the limit of the tensioner, then it stands to reason that the chain will run loose. I believe you indicated that you installed an ACCT. I have yet to see one with a rubber foot. Running loose you'll have metal on metal banging within the tensioner assembly. JAT.

[scoot]

Marty, you are correct in that the acct has a metal foot. And in my earlier pics I think you can see some scratches where it contacts the tensioner plate. I don't think the stock tensioner plastic foot caused these scratches. But the contact surface gets drenched with oil and I'm not overly concerned with the metal to metal contact. And the noise is the same, regardless of which tensioner is in place.

And when I last reinstalled the acct, I did it with the cam cover off and I tested the chain tension over the bridge guide by trying to pull it up hard. It only lifts 3/16". Doing the same with the stock tensioner, I could lift it hard enough to remove the bridge, about 1/2" lift. And that was with the tensioner arm at full extension, locked into place, and then bolted into the hole. When I uninstalled that CCT, the lock bolt was still holding the arm in position, full extension.

So I will never run that stock tensioner again.

scoot

[scoot]

I replaced the cam chain this weekend. Started the motor, and man, that thing sounded so smooth, like a different bike. Geared up , took her out for a spin... and the noise is still here. TAT TAT TAT like a ball peen hammer on a cookie sheet.

So it wasn't the cam chain. But the new cam chain is really nice. Oh, well.

I'll pull the stock headers and see if the double wall in one of them has found a way to get loose and bang around. I did recently ride a long dirt washboard " highway" in Mexico, and at that time I had to stop twice to tighten the fairing which vibrated loose, and had to find a welder to do a repair to a fatigued weld on the back rest. Didn't find any other failed parts at the time, but ...

scoot

[motoman]

I replaced the cam chain this weekend. Started the motor, and man, that thing sounded so smooth, like a different bike. Geared up , took her out for a spin... and the noise is still here. TAT TAT TAT like a ball peen hammer on a cookie sheet.

So it wasn't the cam chain. But the new cam chain is really nice. Oh, well.

I'll pull the stock headers and see if the double wall in one of them has found a way to get loose and bang around. I did recently ride a long dirt washboard " highway" in Mexico, and at that time I had to stop twice to tighten the fairing which vibrated loose, and had to find a welder to do a repair to a fatigued weld on the back rest. Didn't find any other failed parts at the time, but ...

scoot

Still gonna stick with my original diagnosis................vacuum advance vacuum can being the culprit. Remove that left side ignition cover, start the bike and watch the action of that vacuum can. Might be surprised what you see corolates with what your hearing.

[scoot]

Hi motoman, I'll do that too. But I cannot get the bike to make the noise while it is parked. Bike must be moving. And that also makes it tough to accurately locate the source. I have to be in the saddle, under way. Can only get my head and ears so low while steering.

The carb vacuum line was brittle and broke (felt like bakelite) on the #2 carb nipple when I reinstalled the gas tank today. I was able to install the shortened line. I plan to go through the lines and replace as needed, too. Fuel lines are pretty new.

scoot

[scoot]

Swapped out the cam chain

And thought I should share some of that experience.

Bought the chain and masterlink from Z1enterprises and the chain breaker/ riveter tool kit from Mikesxs. Spent another $20 on the tool kit that includes the tooling to repair drive chains as I also have a dirt bike (DR350).

Using the breaker tool, I massively bent a chain link side plate while removing the first link pin due to not having used the tool's lower guide as it was not mentioned in the instructions. I have since added that info to the instruction sheet. Learning curve, no harm, no foul, as that bent plate was part of the full link to be removed. The tool is awkward to manipulate while trying to hold two pieces of very flexible chain still. Another set of hands would be more efficient.

It took about 3 hours from the start of this project to get to the point of riveting the new chain to the old. It took less than 2 minutes to work the new chain around the crank sprocket and back up to the camshaft area. It went around so easily I was grinning in disbelief.

I followed mack's advice and removed the cams. I reasoned that it's something I should be able to do, although I was uncomfortable with it. If the motor was out of the frame, I would have left the cams in place, but with motor in frame, access over the top of the motor where the chain tunnel is, is very limited due to frame tubes, coils, and wire harness and stuff. So working from the sides, it seemed it would be easier with the cams and gears totally out of the way. And now I can pull cams!

After the chain's installed, with the cams and chain in place you can rotate the crank clockwise with your finger pressing the chain inward through the cam chain tensioner hole. It takes only small pressure to keep the chain taut. Do Not try to go counterclockwise with finger on chain, you cannot create the immense pressure needed to do that. With the proper cam chain tensioner installed, you could rotate counter clockwise. I did this while checking the timing marks, if I over shot by 1/16", I could back it to the mark. With my finger as the tensioner, I would have to rotate the crank two revolutions to get the marks back in place.

On the first timing check, it was obvious that I was off 1 tooth on both the intake and the exhaust cam. On each cam, I marked one cam gear tooth and one corresponding chain link, and then pulled the exhaust cam gear off the cam to create enough slack to move the chain off the intake cam gear. Then I used a wrench to slightly move the intake camshaft (1/8"- 3/16"), and placed the chain back on the intake cam gear. At this point, the crank and the intake were in time. Then after using a wrench to slightly move the exhaust camshaft, I installed the exhaust cam gear while it was meshed with the cam chain on it. This was all with the tensioner removed. Now all was in time. Installed the bridge, installed the tensioner, rotated the crankshaft a few revolutions to double check the timing. Done. Then put it all back together. The valve cover gasket was no longer usable, I tried the Permatex The Right Stuff. It's easy to use, probably easier than the paper gasket, it's light gray. I like it.

My old chain was noisy, and the valve train is still toward the looose side, so it's somewhat noisy. This new chain is much quieter, a very mild chain hum not much of a buzz. The valve noise is more noticable than the chain noise, before the swap, it was opposite. All in all it sounds very smooth.

Although this did not resolve my original noise issue, it's nice to know I won't need another chain for years to come. And it's a small job, can be done in one day. I did it in two half days.

scoot

[scoot]

Problem resolved. turned out to be the inner wall of the #1 header pipe had fractured completely around the interior. The noise as described in my first post was the fractured ends banging and vibrating together inside the pipe. First paragraph from first post:

"The engine started to sound pretty rackety about 200 miles ago. At around 3,000 rpms it would start to sound like a ball peen hammer hitting sheet metal like a machine gun on up to 4500 rpm, then fade away above 4500. I rode it like that back home about 100 miles. Tried to keep it out of that range as best I could. Noise came from the top of the engine, up front. And it only happens under load, rolling. Cannot get it to happen at full stop in neutral."

Haven't read of this issue here before although I may have missed it, so here's some pics to illustrate. And I had the mig welding done by a local muffler shop for $20 since I knew if I did it myself I'd be melting away that thin wall and making it worse with my oxy acetyline set.

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What I found.

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Cleaned up with dremel and grinding stone

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mig welded, heavy bead

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Smoothed down with dremel and same grinding stone

Road test proves the problem is eliminated. Thank you all for your help. And the answer is, No, it's not time to change the cam chain , but it sure is nice.

scoot