Stretched cam chain?

[norcalwelder]

I had a ticking sound that sounded like a text book case of a bad cam tensioner. I pulled the tensioner off today and was surprised to see that it was right at the end of its travel. I pulled the inspection cover off and the guides didn't look like they were worn out, so that leaves the chain and sprockets, correct? I don't think cam chains stretch much, but I do have 50,000 miles on the bike. Any ideas?

 

[adberns]

While I am unsure if its common on these bikes (doesn't seem to be, from what I read), cam chains in general can stretch until the tensioner won't take up the slack anymore. Some bikes have a worse problem with this than others.

For instance, my brother-in-law has a 1996 Suzuki Savage, and these models are notorious for cam chain stretch. At 10k miles, the chain was stretched so badly that the stock tensioner was completely out of its body - the spring had pushed the plunger completely out! I even have a video of the noise:

[ame="http://www.youtube.com/watch?v=txBAxgXLlwc"]Loose cam chain on a Suzuki Savage[/ame]

 

[FinalImpact]

I had a ticking sound that sounded like a text book case of a bad cam tensioner. I pulled the tensioner off today and was surprised to see that it was right at the end of its travel. I pulled the inspection cover off and the guides didn't look like they were worn out, so that leaves the chain and sprockets, correct? I don't think cam chains stretch much, but I do have 50,000 miles on the bike. Any ideas?

JMO, but the guides would be hard to see the wear depth with the chain in place. Anyway, you likely have a tolerance stack up of both items i.e. chain is stretched and the guides are worn. Like the final drive chain, I'd bet there is a specific count of links / per mm or inch. But by the time you get it out to measure it, you may as well replace it. Just a bit more work than spark plugs I suspect!

Negative on that: unless you can find the spec somewhere else. . .
Timing chain:
Model/number of links 92RH2015/120
Tensioning system Automatic

Has the head ever been off or the head gasket changed? This could make it loose if the head was milled or a thinner gasket installed. I've never had one apart at 50k so I can't offer much more. . .

 

[norcalwelder]

As far as I know the head hasn't been off. You can't take a link out of a timing chain can you? The only good thing about this whole issue is that the timing isn't too bad. I was going to pull the valve cover and check my valves for the second valve check interval pretty soon, so I can do both at the same time.

 

[adberns]

No, you can't take a link out of the timing chain, you'll have to replace it. Well, I guess in theory you could take a link out -- it is, after all, a chain -- but supposing you do get lucky and it still fits, you have to hope the links don't break, or stiffen, or ...

If the chain has stretched beyond spec, it's worn out. Replace it in its entirety.

 

[norcalwelder]

Looks like its recommended to replace the sprockets with the chain, those little guys aren't cheap! I suppose in the grand scheme of things it isn't too bad though, because I'm doing the work myself with keeps the cost down.

 

[VEGASRIDER]

I had the Cam Chain replaced, as well as the sprockets, including the guides. And since the head was off, I had the valve adjustment performed. Bad news is that most shops will not carry all of the items mentioned above, and some of the parts will have to come from Japan.

I had about 75k on the clock when this was performed. I think it ran like $700 after all said an done. Plus new plugs!

 

[GTPAddict]

It hasn't been mentioned but the OP said , " I pulled the tensioner off today and was surprised to see that it was right at the end of its travel." The tensioner is spring loaded, so as soon as you start pulling it off it will extend. I'm pretty sure you'd never be able to see how far extended it actually was while installed.

CHECKING THE TIMING CHAIN TENSIONER
a. Lightly press the timing chain tensioner rod into the timing chain tensioner housing by hand.
While pressing the timing chain tensioner rod, wind it clockwise with a thin screwdriver 1 until it stops.
b. Remove the screwdriver and slowly release the timing chain tensioner rod.
c. Make sure that the timing chain tensioner rod comes out of the timing chain tensioner housing smoothly. If there is rough movement,replace the timing chain tensioner.

 

[norcalwelder]

It hasn't been mentioned but the OP said , " I pulled the tensioner off today and was surprised to see that it was right at the end of its travel." The tensioner is spring loaded, so as soon as you start pulling it off it will extend. I'm pretty sure you'd never be able to see how far extended it actually was while installed.

CHECKING THE TIMING CHAIN TENSIONER
a. Lightly press the timing chain tensioner rod into the timing chain tensioner housing by hand.
While pressing the timing chain tensioner rod, wind it clockwise with a thin screwdriver 1 until it stops.
b. Remove the screwdriver and slowly release the timing chain tensioner rod.
c. Make sure that the timing chain tensioner rod comes out of the timing chain tensioner housing smoothly. If there is rough movement,replace the timing chain tensioner.

When I loosened the bolts holding the tensioner in, it should have pushed itself out from the mounting block on the side of the engine. In my case, it backed out 1/8" of an inch or less. The total range of the tensioner was about 1 and 7/8" and it was working smoothly and correctly. This is why I thought it was out of travel.

 

[GTPAddict]

Ah, I see. Well it was just a thought...

 

[TownsendsFJR1300]

When I loosened the bolts holding the tensioner in, it should have pushed itself out from the mounting block on the side of the engine. In my case, it backed out 1/8" of an inch or less. The total range of the tensioner was about 1 and 7/8" and it was working smoothly and correctly. This is why I thought it was out of travel.

You NEED at least a cam chain. If the guides are worn (you'll see them once the cover is off) replace them too. Classic worn chain, my old 2005 KLR 250 (3x's as long a cam chain) showed the exact symptoms. A new chain, REAR GUIDE (THAT THE TENSIONER PUSHES AGAINST), nice and quiet, about 26,000 street miles on it at the time.

IMHO, cam sprockets wouldn't hurt to change out (about $45 apiece, $25.00 for the chain wouldn't hurt) but are likely ok.

I would replace the rear guide for certain. You really can't see much difference between the new and old but that little bit does indeed make a difference.

The below picture is my KLR tensioner with the new CHAIN and REAR guide installed. Before, the tensioner was maybe 1/16" from the block fully extended..

 

[norcalwelder]

You NEED at least a cam chain. If the guides are worn (you'll see them once the cover is off) replace them too. Classic worn chain, my old 2005 KLR 250 (3x's as long a cam chain) showed the exact symptoms. A new chain, REAR GUIDE (THAT THE TENSIONER PUSHES AGAINST), nice and quiet, about 26,000 street miles on it at the time.

IMHO, cam sprockets wouldn't hurt to change out (about $45 apiece, $25.00 for the chain wouldn't hurt) but are likely ok.

I would replace the rear guide for certain. You really can't see much difference between the new and old but that little bit does indeed make a difference.

The below picture is my KLR tensioner with the new CHAIN and REAR guide installed. Before, the tensioner was maybe 1/16" from the block fully extended..

Thanks for the info! I hate to pull decent looking sprockets off and replace them for $100 if I don't need to, but don't you see premature wear if you have a new chain and sprockets that haven't worn in together?

 

[TownsendsFJR1300]

Their cam chain is in constant oil, sealed if you would, its not like neither see lubrication as the mechanic see's fit (drive chain-exposed to the elements).

Chain wear, especially the smaller ones (such as the cam chain) stretch faster vs the rear wheel chain.

**I just re-read your first post. With 50,000 miles on the clock, IMHO, I'd change out the sprockets (or be ready to order them), they really have served their purpose..

As stated earlier, your already there, it'd be another $100 or so for sprockets (and piece of mind), but I'd definitly change out the rear, (pressure pushing on the chain from the tensioner), guide.

I don't know if you'll have the room or not, but you may be able to remove the sprocket bolt(s) with the cam(s) STILL installed in the head, its only one bolt for each cam. If there is room, keep the old cam chain on with everything lined up and crack the cam sprocket bolt(s) loose. (The old cam chain will hold the cam(s) from turning vs pulliing the cam, clamping carefully in a vise, etc)

You'll have the valve cover off to line up TDC, I'd check valve clearances while your there...

It'll be nice and quiet when your done...

BTW, I didn't change out the sprockets on my 2005 KLR, just the rear tensioner guide, but it is easily 3x's longer, (buried in the engine) red lines at 9,000 RPM not 14,000 RPM's. My previous 1989 KLR 250, it was still on the original cam chain when I sold it at approx 73,000 miles (did go thru two LS main crank bearings thou)

 

[norcalwelder]

I ordered up the parts, so hopefully next Saturday I'll pull her down and get everything changed. I didn't order the sprockets because I can mic the lobes when I get the valve cover off and check the wear then.

 

[norcalwelder]

The cam sprockets looked pretty good, but the old chain was 3/16" longer and the guides were worn pretty badly. It took me 7 hours from start to finished, and I got the valves checked too. They were all fine. It started right up and ran pretty well, although it doesn't idle as smooth as before. I need to synch the TB's most likely. Except for a few random noises that went away quickly, it sounds pretty good and runs well. You can definitely hear the injectors, but the chain noise seems to be gone. I rode about 15 miles tonight after putting it back together, and I'll ride it more tomorrow to see if its going to be good to go. I didn't realize that I had to pull the cams to change the chain, so that definitely added some pucker factor.

 

[TownsendsFJR1300]

The cam sprockets looked pretty good, but the old chain was 3/16" longer and the guides were worn pretty badly. It took me 7 hours from start to finished, and I got the valves checked too. They were all fine. It started right up and ran pretty well, although it doesn't idle as smooth as before. I need to synch the TB's most likely. Except for a few random noises that went away quickly, it sounds pretty good and runs well. You can definitely hear the injectors, but the chain noise seems to be gone. I rode about 15 miles tonight after putting it back together, and I'll ride it more tomorrow to see if its going to be good to go. I didn't realize that I had to pull the cams to change the chain, so that definitely added some pucker factor.

Glad you got it done, got the valves checked too, saved a bunch of $..
3/16" in such a short chain is alot... You kept the original tensioner too correct?

Did you notice how far out the extended tensioner NOW EXTENDS from the block vs the old one, just curious?


One last question, IF you removed one cam sprocket gear from a cam(either one), would the chain have enough room to clear the block and the other cam gear? (thus NOT REMOVING THE CAMS)..

 

[norcalwelder]

Glad you got it done, got the valves checked too, saved a bunch of $..
3/16" in such a short chain is alot... You kept the original tensioner too correct?

Did you notice how far out the extended tensioner NOW EXTENDS from the block vs the old one, just curious?


One last question, IF you removed one cam sprocket gear from a cam(either one), would the chain have enough room to clear the block and the other cam gear? (thus NOT REMOVING THE CAMS)..

Before I had maybe a little less than an 8th inch that the the tensioner would stick out with the bolts loosned. Now, over a half inch. As far as I could tell, you cant get the chain out without the cams coming out. With the sprockets off, the chain would fit if it had a couple hundreths more clearance. Close but no cigar. The manual was hard to follow, but without a doubt, invaluable.

 

[FinalImpact]

So you stretched the chain into a big oval and found it to be 3/16" longer?

So basically half of the 3/16" 0.187" stretch would allow the cams to retard a small amount. Divide length in half = 0.094" (not much but some). Does the performance feel any different?

 

[TownsendsFJR1300]

So you stretched the chain into a big oval and found it to be 3/16" longer?

So basically half of the 3/16" 0.187" stretch would allow the cams to retard a small amount. Divide length in half = 0.094" (not much but some). Does the performance feel any different?

When I changed out the cam chain on my old KLR 250(and it wasn't as stretched as his), there was a noticable difference in performance.. You have to remember the guides were worn too making the timing even worse...

I suspect the FZ would be the same..

 

[norcalwelder]

So you stretched the chain into a big oval and found it to be 3/16" longer?

So basically half of the 3/16" 0.187" stretch would allow the cams to retard a small amount. Divide length in half = 0.094" (not much but some). Does the performance feel any different?

The RPM's climb faster, and the engine sounds more growly. (Not sure why on the sound) How I measure it was I stretched the new chain and the old chain out together lengthwise and found the old one extended past the new one by that amount. Oh, and the idle is lumpy as well as too high, which a throttle body synch should take care of as soon as mine arrives.