Cam Chain tensioner rod question

[ThatXS650Guy]

Had a mishap the other day when my cam chain tensioner backed out while I was riding. Lost a bit of oil but was able to get it back in and keep going. I have it out today to assess any damage and I cannot get the proper "flush" adjustment. Taking it out it seems my tensioner rod is not long enough to get any adjustment at all. In fact, without the spring the rod is still not flush with the end of the threaded shaft. The tensioner rod is 99.3mm long? Is that the proper length? If I take the small, thick copper washer out I can get a little more adjustment but not much.

 

[Jim]

It's possible that without the tension, the chain beat up the rubber on the guide and the tensioner. Possible even that the guide rubber is now laying down in the sump and there just ain't enough adjustment to make up for that. Prolly not what you wanted to hear.....

 

[5twins]

Your plunger sounds correct (about 100mm long). The question is, how long is your adjusting screw? Your type E adjuster came in 2 versions. The difference is in the adjuster screw length. One is 60mm long, the other 59mm. The length was changed when the damper washer was changed from the 2mm thick copper one to a 3mm thick rubber/metal one. The slightly shorter adjuster screw was needed to make the rod come out flush again with the thicker washer.

If your screw is longer than noted above, it may have been swapped in from some other tensioner assembly, or maybe even a different bike model's tensioner.

 

[Jim]

and I cannot get the proper "flush" adjustment.

Shoulda asked.... could you get the proper flush adjustment before it came loose?

 

[ThatXS650Guy]

Thanks 5Twins. I am confused. If the rod is flush with the adjusting screw only when the spring is fully compressed where is the adjustment? My manual shows an overtight condition where the rod end is proud of the adjusting nut. With the setup I have that is impossible. The rod only extends past (or barely gets flush) with the adjusting screw when the spring is completely compressed. Is that how it is supposed to be?
The adjusting screw is 60mm.

Shoulda asked.... could you get the propper flush adjustment before it came loose?

I checked it before and it was flush with adjusting screw. I don't recall having to mess with it.

 

[5twins]

The coil spring is what applies the adjustment or tension against the tensioner shoe and chain. Screwing the adjuster screw in more tensions the spring more and that pushes the plunger in harder against the shoe. You need some "give" in the adjustment because of the tight spots in the chain. Loose sections on the chain allow the spring to push the plunger in and take up the slack. Tight sections push the plunger back out against the spring. That's why the tip bounces in and out at the end of the adjuster screw. You're seeing the plunger running over tight and loose sections of the chain.

Yes, the plunger will bottom out against the back end of the adjuster screw at tight spots on the chain. That's what the soft damper washer is there for, so it doesn't tick like loose valves when this bottoming out happens.That's what the adjustment procedure is all about, to get it so it just does that without being too tight. Then at the loose sections of chain, the spring can move the plunger back in a little bit to take up the chain slack. No in-out plunger movement means you've got the adjustment set too tight. The plunger is bottomed out against the bottom of the adjuster screw and pushing hard on the shoe. This puts undo strain on the parts and on the chain when tight spots run by.

You're right, with the proper (and unworn) parts, it's not possible for the plunger to come out past the end of the adjuster screw, at least on the later type D and E assemblies I'm most familiar with. It can on the late type E version if the wrong (thinner) copper washer is used. It is 1mm thinner than the correct rubber/metal washer that version was designed to use .....

 

[xjwmx]

I suspect everything is okay and that you just never paid a lot of attention to the adjuster before (obviously?). I seem to remember it takes the spring fully collapsing to be flush. As for "where is the adjustment", I think the spring is so weak it doesn't put any significant pressure on the chain. I think the spring is just there to keep the adjuster in contact with the chain when it comes to a looser area in the chain. One way we adjust the chain on this board is with the engine running and hot, tighten until there's barely plunger movement, then back it off until there's about 1mm of movement.

 

[ThatXS650Guy]

Ok Thanks Everyone. I'll adjust per xjwmx's recommendation.

 

[5twins]

I'm also going to add here that MikesXS sells the thicker rubber/metal washer and claims it is an improvement/upgrade and will retrofit earlier models. It is neither. It doesn't work any differently or better than the earlier copper one and if fitted to an earlier tensioner, the rod will no longer come out flush with the end of the screw. This can make adjustments difficult because you can't see the rod end very well. And if you do go ahead and crank the piss out of the adjuster so the rod end is flush, you end up with a chain set waaaaaaay too tight, like bow string tight.

 

[xjwmx]

The problem with simply setting it for 1mm of movement is that you get that with the chain loose enough to be rattling At least with mine. So it's probably better to come to it from the opposite, overtight, direction.

One gotcha there is if the wrench slips off the lock nut it will likely make a raised place on it that keeps the cap nut from going all the way down -- oil leak. If that happens just file the bastard with the bastard file.

P.S. I keep changing the way I adjust the cam chain lately. Here's how I would suggest at the moment: Adjust cold to eliminate chain rattle, and check for movement. Then check hot to be sure you still have movement.