Another cam chain tensioner thread

[maxdog]

Hello all,
Been a lurker for quite a while and have learned a lot by reading ( and re-reading) the posts here. Let me say from the get-go, that I really appreciate all the good advice here. You folks have really helped me on the bike thus far, and I greatly appreciate all the contributions!!

I have a 1980 Special that I received in semi-running condition. Bike is in very good condition. Over the process of time, and using the posts here, I have replaced the rotor, cleaned the carbs and got it to start and run on a regular basis.

There is, what sounds to me, a pronounced sounding "chain noise" from the engine. Keep in mind, that I only heard this bike run one time briefly before buying it, and did not know much about these bikes then. So, I don't really know what "normal" sounds like. This noise seems significant, but I have read that these bikes are noisy. But I thought I would ask the experts. I started looking at the cam chain tensioner adjustments.

So, I have been reading up on the cam chain tensioner. The posts I have read here don't seem to address what I see when I try to adjust the tensioner. Or I am more clueless than I thought and not understanding the posts! I took the tensioner assembly off, and the rod, spring, copper washer and adjuster all look OK. FWIW, while I had the tensioner off, I noticed that if I compress the rod all the way, the tip just comes even with the outside of the tensioner. Don't know if this is normal.

When I have the tensioner mounted, no matter how far in I adjust it in, or how far out, the tip of the rod stays below the surface of the end of the tensioner about 1/8th inch as I rotate the rotor. It does not seem to move. EXCEPT for one brief spot where the tip of the rod jumps out dramatically to flush or a bit further depending on its current setting, and as I continue to rotate it jumps back in to where it was.

I also tried doing some adjustments while idling, and the chain noise does not seem to change at all.

So based on all the posts, where is the 1-2 mm to be measured? Is this the distance it "jumps" from inside the hole to its furthest extension? Or is the rod supposed to be moving apart from that "jump"?

Hope this makes sense. I appreciate any advice you can give. Haven't ridden the bike yet, but anxious to do so.

Thanks in advance!!

 

[xjwmx]

I have an '81 which is the same as yours as far as the tensioner goes, I do believe. There's no reason to remove it. Find a diagram to make sure you have all the parts, in the right order. The 1-2mm you read about is how much it moves in totality - possibly partly in and partly out of the adjuster.

One easy way I have found to adjust the tensioner, and it got the blessing of the supreme guru of the xs, whose name and web moniker I forget, was to do the following:

With the engine cold, turn the adjuster out until you're sure it's loose. Then turn it in with your fingers only until you can't turn it in any more. At that point you should find that it's tight enough to not rattle, when warmed up at least, but loose enough to not put unnecessary pressure on anything. This works only with the engine cold.

 

[maxdog]

Thanks. Unfortunately, the threads on the adjuster are buggered up a bit so hand turning is not really an option. Not knowing the history of the bike I was wondering if the actual rod was too short? I cannot seem to get the rod itself to come out any further than about 1/8th inch below the surface of the threaded portion. EXCEPT for when in "jumps" out. By adjusting the tensioner, I can get the rod to jump out further or less, but at all other times, the rod just stays about the 1/8th inch below the end of the tensioner.

 

[xjwmx]

^I would say you need to put up a picture of it, but since the threads are messed up you need to replace it anyway.

The classifieds here are real active so you might find one here. Ebay, for sure. Look at pictures for compatible years and make sure the thing on ebay is the same, regardless of what they call it there. Your question now should be what years of adjuster will fit your bike. They will be priced fairly cheap.

 

[XSLeo]

There is aossibility that a PO has been in there and swapped parts around. Here's a pic of a 75, the lower, and an 82 , upper. You can see the differences in the adjuster body and the plunger.
In the second pic I assembled all the parts as they should go but left the spring out to ease taking the pic. You see the plunger comes out about the same on both.
Different years used different dampers, some just a copper washer others the rubber steel composite dampers.
In the 75 it has the rubber composite one. The 82 has none, didn't have one when I took it apart.
If all your parts together and the plunger won't come out past flush it will make adjustment a bit tougher.
If everything is right as you turn the engine over, watch the plunger. It will jump out past the adjuster at the same point in the revolutions as you turn the engine. It does this because the bvalve spring tend to puish the cam around faster just as the rocker arms go past the high point on the cam lobes. A normal thing.
To adjust find any place but that point and loosen the adjuster up a bit and the spring pushes the tensioner and chain in so the plunger goes inside the adjuster, now turn the adjuster out till the lunger comes just flush with the end of the adjuster.
Now if you start the engine and watch the plunger it will move in and out a bit. With the engine warmed up you can adjust the tensioner so the movement is 1 to 2 mm. Coming out to flush but never past flush.
This works with all the right parts in the adjuster. Even if the parts are mismatched you can get a proper adjustment by adjusting with the engine warm and at idle. Adjust the tension so the plungher moves 1 to 2 mm. Even if it doesn't come flush, it will be harder to see is all. If it moves less then it's to tight, if more to loose.
If you want you could shorten the adjuster screw on the end where the spring sets enough so you get a bout 1/16 or so protrusion of the plunger as in my pic or shop around for different parts. On Ebay you often find complete tensioner assemblies for not to much.
I might try that before modifing yours.
Leo

 

[maxdog]

xsleo,
Thanks for the info. I have what appears to be the type E tensioner. The copper washer/damper is in place. When I compress the rod/plunger with spring and washer in place, while the assembly is out of the bike, the rod/plunger tip extends to only flush with the nut, and no further. Wondering if the PO may have mixed parts. Is there someone who can provide an overall dimension for the rod/plunger? Curious to see if the rod/plunger is of the proper length.