Cam Chain Tensioner Failed

[jennings2309]

Frustrated and seeking support. My recent acquisition had low compression on several cylinders and was burning oil. So I decided to add new rings.

Added the new rings and reassembled. I must have left some slack between the crankshaft and intake cam sprocket. The hand turnover of the engine was fine, but when I ran the new compression test, I got 2 cylinders done then the motor clanked hard and refused to rotate.

I pulled it apart and found that I has bent three intake valves. I started looking through all the parts and discovered that the cam chain tensioner will not tighten up. The big set screw has all kinds of metal shards on it, like the stripped threads from the casting, no doubt.

I have a spare set of valves and replaced the bent ones. I have reshimmed the valve clearance. I dare not reinstall the weak, stripped out cam chain tensioner. It may be the culprit.

So I ordered a new, original model and will install on arrival. It is just frustrating to have to wait. And of course, there is always the doubt that the tensioner is not the major issue, but perhaps my lack of expertise. Following the manual is easy enough, but I am ready for some success with this rebuild!

OK, bile spewed, back to the reality. It will not fix itself...

[skids]

Frustrated and seeking support. My recent acquisition had low compression on several cylinders and was burning oil. So I decided to add new rings.

Added the new rings and reassembled. I must have left some slack between the crankshaft and intake cam sprocket. The hand turnover of the engine was fine, but when I ran the new compression test, I got 2 cylinders done then the motor clanked hard and refused to rotate.

I pulled it apart and found that I has bent three intake valves. I started looking through all the parts and discovered that the cam chain tensioner will not tighten up. The big set screw has all kinds of metal shards on it, like the stripped threads from the casting, no doubt.

I have a spare set of valves and replaced the bent ones. I have reshimmed the valve clearance. I dare not reinstall the weak, stripped out cam chain tensioner. It may be the culprit.

So I ordered a new, original model and will install on arrival. It is just frustrating to have to wait. And of course, there is always the doubt that the tensioner is not the major issue, but perhaps my lack of expertise. Following the manual is easy enough, but I am ready for some success with this rebuild!

OK, bile spewed, back to the reality. It will not fix itself...

I hope that you did the oil seals too. Hey, the tensioners suck on these machines. The adjuster screws strip very easily and once they do, they slip. If they do slip, they can actually hold the plunger in a looser position. This happened to one of my 78E’s. VERY discouraging.

Do not even think about reusing that tensioner (as I know you are not). You can install an automatic tensioner but if you do, it is best to to the install with the cam cover off so that you can ensure that the timing marks are alligned.

[Schming]

"So I ordered a new, original model and will install on arrival."..

IMHO you'd be safer to install the ACCT rather than use the poorly designed original style.

There are a lot of threads on the replacement procedure and the donor types.

I believe mine came from a mid eighties XVZ Venture.

As with all bikes there are a few other mechanical and electrical quirks that may or may not need addressed on these vintage beasts but once taken care of they're a blast

Welcome to the Madness !!!

[IanDMacDonald]

Oh, the dreaded tensioner. Been there brother. Just learn from the mistake, and ride on.

[Ken Talbot]

It is a simple (i.e. cheap) fix, to put a helicoil insert into the body of the CCT. Do that, and it will last forever. BTW - clean up any burrs on the shaft while you've got it apart so it moves smoothly when adjusting.

[Schming]

It is a simple (i.e. cheap) fix, to put a helicoil insert into the body of the CCT. Do that, and it will last forever. BTW - clean up any burrs on the shaft while you've got it apart so it moves smoothly when adjusting.

I agree with all the above, even the point of moving smoothly which is the culprit.

Known experience by more than a few members has revealed that upon an abrupt deceleration of the engine some stock CCT's have slipped with the pressure.

With all respect IMHO there is a reason that Yamaha upgraded to the ACCT.

Link to cross references for the ACCT:

http://www.xs11.com/forum/showthread...highlight=ACCT

[skids]

I first bought one that was on the list that should have worked. It didn't.

Then I bought one from ebay listed as "1983 Yamaha Venture XVZ1200 XVZ 1200 cam timing chain tensioners" . It was pretty much plug-and-play except the mounting bolts need to be a little shorted than XS11's. It works very well.

[JeffH]

Sorry to hear you had some unexpected problems after installing those new rings.
Since you mentioned "burning oil" we assume you had been riding your 11 a bit before the teardown for those new rings?

Another Cam Chain tensioner option that works well:

Can find these USED or the used V-Max ACCT's on eBay for $25 or $30 bucks

As mentioned, its best to have the cam cover off and visually check and double check those cam alignment timing marks. BTW, do you have an xs11 manual or downloaded one of the manuals?

Good Luck with the fix. Post an update and pic of your bike when you can.

Jeff

[Radioguylogs]

It is a simple (i.e. cheap) fix, to put a helicoil insert into the body of the CCT. Do that, and it will last forever. BTW - clean up any burrs on the shaft while you've got it apart so it moves smoothly when adjusting.

So far, I'm using the original adjusters on my XS11's. I did use a file to remove detents on the plunger from previous over-tightened settings, so the new setting doesn't want to slip into a previous setting.

[MPittma100]

Acct

The newer ACCT tensioners are the fail-safe, fool-proof upgrade that all should consider. Install one and chain adjustments are a thing of the past. Do it!

[skids]

It is a simple (i.e. cheap) fix, to put a helicoil insert into the body of the CCT. Do that, and it will last forever. BTW - clean up any burrs on the shaft while you've got it apart so it moves smoothly when adjusting.

Ken, I did that to a tensioner on one bike, but I eventually switched over to an ACCT on the other bike, because I just didn’t like the way the stock one worked. Stock tensioners are so iffy with the friction dependence, the use of a baby torque wrench to get it just right, the possible sorce of oil messes, yadda yadda. I installed one (ACCT) on Cherry and I do have one more to install on the Beast.

[jennings2309]

Got some good news to close out this thread. Completed new tensioner install, reassembly, and adjustments.

Put all the intake, carbs, and exhaust back on. Turned it over and it started right up! Let it warm up for 2-mins then cut choke off. She idles real nice and revs smooth - no hesitation through the power band. Dare I say she is ready to ride? Got some 65F days in the forecast here in Georgia. Need to get her out there.

Thanks to all who helped with ideas, advice, and well wishes.

[jennings2309]

Got some good news to close out this thread. Completed new tensioner install, reassembly, and adjustments.

Put all the intake, carbs, and exhaust back on. Turned it over and it started right up! Let it warm up for 2-mins then cut choke off. She idles real nice and revs smooth - no hesitation through the power band. Dare I say she is ready to ride? Got some 65F days in the forecast here in Georgia. Need to get her out there.

Thanks to all who helped with ideas, advice, and well wishes.

Photo added:

https://photos.google.com/album/AF1Q...1jrNuRdEtfbqp8

[bikerphil]

Good for you, nice when she's up and running again. Ride safe.
Pic link didn't work even after sign in to Google.

[jennings2309]

More Picture Links

Here's other pic links - lets see if they work!

https://www.snapfish.com/photo-gift/...37070/SNAPFISH