Cam Chain Adjustment Problems

[AnthonyXS]

Hi All,

I am having some issues with my Cam Chain adjustment. Have owned my 1978 xs650 for two weeks, has it checked up with a mechanic before I purchased it and he gave me the usual list of maintenance issues that need to be taken care of on an older bike, but the general ok.

Issue at hand: valve lash noise on every combustion (clicking / metal tapping when engine is running). I figured I'd check the cam chain tensioner, since I've read that that could cause the problem.

I take off the big Acorn nut and see that there is no lock nut in there!! The adjustment nut is screwed way, way further in than any of the videos or diagrams I have referenced, but the pushrod is ALSO way, way in to the adjustment nut. Very strange. In order to get the pushrod flus with the shoulder of the adjustment nut, i have to screw the adjustment nut so far in that I don't even have any thread left to screw the acorn nut back on.

Why is it so drastically off, and how have I been riding this bike for the last two weeks without the cam chain slipping or anything? What to do?

Thanks in advance for any help!

Anthony

 

[Downeaster]

Something is either worn completely out or broken.

I'm not sure all years are the same, so take this with a grain of salt, but on my '80 engine, the cam chain tensioner consists of a shaft with a ball-shaped end that pushes on the chain slider, a spring, the adjuster barrel that screws in or out, a locknut and a cap. (The locknut I know wasn't used on at least one year).

The way it works is that you adjust the spring tension by screwing the adjuster barrel in to increase the pressure on the spring. You know it's right when the end of the shaft with the ball end on it is basically flush with the end of the adjuster barrel.

You say you can screw the adjuster barrel nearly all the way in without seeing the end of the shaft sticking out. I can only think of three things that could cause that:

1. The spring is broken or has collapsed.

2. There's way, WAY too much slack in the cam chain.

3. At some point, some ham-fisted PO broke the end of the shaft off.

Any of these three things is flirting with disaster. If that chain gets sloppy enough to let the cam jump a tooth (not positive that's possible, but worth worrying about IMHO) you're going to wind up with a valve down and a piston up at the same time, and trust me...that ain't good.

Sorry to tell you this, but I think the Right Thing To Do is to pull the engine out of the bike and tear the top end down to see what's going on.

Maybe someone else that's had a similar problem can shed some light on other options.

 

[Paulrxs650]

As Downeaster says it could be broken part. Best way to check first is remove the tensioning mechanism. Depending on your model (pics would help) you can un do six bolts and remove the whole mechanism. There, depending on model, you should find the spring, damping washer and components. 5 twins posted up a comparison but I dont have it to hand. There are comarisons in this thread including a video - http://www.xs650.com/forum/showthread.php?t=13058&highlight=cam+chain+adjustment
Dont run the bike until youve worked out the issue.

And as before some pics of your tensioner will help us identify the type

 

[5twins]

Yes, you need to take a look at your tensioner components and I agree, don't run the bike until you sort this. It could be anything already mentioned or maybe incorrect components swapped in from a different year tensioner assembly. There were several used over the years .....

The no lock nut type D was the usual set-up on a '78 but it's possible some of the components have been swapped. You can pull the adjuster screw/spring/plunger out of the housing with it still mounted on the engine and examine them. Here's what type D components should look like .....

Many find the copper damper washer missing and that can cause excessive ticking, but it wouldn't make the assembly act like yours is doing, needing to be tightened in so far. You'll want to measure your plunger length. Maybe it's the wrong one or has been modded by a P.O. Here's the type D and E ones compared .....

Some other measurements to check would be the adjuster screw (55mm of thread, 6mm hex head, 61mm O.A. length) and spring (about 52mm free length).

 

[AnthonyXS]

@downeaser, @Paulrxs650, @5twins, you guys are all saviors! Thank you so much for your help. I've attached 4 images.

1: Bolted, just to see the type. Based on this image and following images, it is definitely type D. My bike's a 1978 xs650, so that corresponds. The drastic amount that the pushrod is sunk in to the adjuster makes me want to think its a mismatched cam-chain adjuster unit, but since its the right year it must be the right one. As far as I know, the assembly itself has never been swapped.

2: This is about the adjustment that the bike was at when I purchased it, and rode it like that about 50KM. Bad news. The pushrod is pretty damn far in there, and i can loosen/tighten the adjuster with my bare hands easily

3: Pushed a little further in, still can't get the pushrod protruding or even flush.

4: Pushed so far in that there's no way to screw the acorn nut back onto those threads, still no pushrod protrusion! I'm guessing and hoping mostly due to it having the original cam-chain, extremely worn and stretched. Hopefully there's no other issue.

Im going to go ahead and remove the adjuster screw/spring/plunger and assess the situation.

Either way I'm going to have to switch the cam chain. I'm a complete beginner, so this is going to take some serious research/videos/diagrams. Any good how-to's on cam-chain replacement out there?

Thanks so much again!!

 

[AnthonyXS]

Well, its definitely type D. I took it out, measured it and it's type D exactly. I also took note that the spring looks exactly as new or worn as the one in the example image you showed me (i counted the # of coils that cover the shoulder of the end of the pushrod, 4 in the image and 4 on mine.

So, lets hope it's just the world's loosest cam chain? Now on to doing some serious cam chain removal research, I guess i'm gonna have the take the jug off for the first time.

 

[gggGary]

I will suggest you drop the sump and side filters tell us what you find. Is your engine making a whirring noise like metal scraping? I will guess you have lost the rubber shoe off the front cam guide. A common issue on these.

 

[AnthonyXS]

Hey @gggGary, the engine actually sounds really good apart from the metal clanking which I have to assume is the cam chain clanking around cause its so damn lose, or otherwise valve lash from poorly adjusted valves.

Nothing that matched the sound you described. Does checking the filters have anything to do with the issue your mentioning? Is it because you predict that I'll find plastic in the oil/filters?

Unfortunately I'm leaving town now for 10 days, but the day I get back I'll check the filters! Thanks so much!

 

[gggGary]

Yeah black rubber from the guide. That guide, fallen off or sawed through is the most likely reason I can think of for the chain to be so loose.

 

[5twins]

I'm not sure a bad front guide would contribute to the chain being so loose. It doesn't tension the chain at all. The rear tensioner could be badly worn, with a big groove worn into it. That would account for the slack. I'm thinking a P.O. ran this chain set way too tight, maybe multiple times (after every adjustment) and that stretched the shit out of it, along with wearing the rear tensioner blade out.

Or, this could be a case of that type D adjuster with no lock nut being the cause. We discussed this recently. Tightening the acorn nut may have tightened the adjuster more with it. So, every time the P.O. did a cam chain adjustment and then put the acorn nut back on, he inadvertently made the adjustment tighter. Honestly, I've never seen a chain stretched this much and I'm not sure it's even possible. That rear tensioner blade must have a giant groove worn in it too.

If my theory is correct then that verifies my belief that the type D tensioner is bad news and should be updated if you have one. So, on the type D tensioner, it appears the D stands for "Deadly", lol.

 

[AnthonyXS]

Hey 5twins thanks for the input, I actually went to bed last night thinking the same thing. Either way, I'll check the out to make sure it's plaric-free since the loseness and slapping might well have taken that cam guide lose.

gggGary that sounds right, right?

5twins: are the cam chain tensiones interchangeable? If so which one would you suggest I swap the assembly out with if the problem does seem to be worn rear tensioner blade from over tightened tensioner?

Thanks to you both!

 

[5twins]

Upgrade to the E type. The D and E type are the same with the exception of the longer plunger and the addition of the lock nut and its sealing washer. Those parts can be swapped onto and into your current housing. Spring, adjuster screw, and acorn cap nut are the same.

You will probably have a hard time finding just a plunger and lock nut but complete tensioner assemblies are readily available on eBay for about $20 to $25. In fact, someone just bought a $20 one out from under me that I was about to purchase, lol. Must be someone reading these threads I bet. Here's another auction ending shortly, no extra charge for the purple spray bomb paint job, lol .....

http://www.ebay.com/itm/1980-YAMAHA...Parts_Accessories&hash=item43cc6f2453&vxp=mtr

 

[XStretchified650]

Yep 5twins...you called that one right. While you were on here answering questions I was buying that $20 type E.

So it appears that my type D tensioner took it's last road trip on Saturday...did 365 miles but it's going to be retired when the mailman brings the replacement.

XStretchified

 

[5twins]

I scored another so no worries. If you find you need a new copper seal washer for the lock nut, Mike's has them. O-rings for the acorn nut can be had from McMaster-Carr, less that $4 for a lifetime supply .....

http://www.mcmaster.com/#9452k81/=sz6vqt

Yes, this is an American size but it's a perfect fit.

 

[AnthonyXS]

Thanks guys!

@XStretchified650 what was your reason for switching to the E-type. How are things going after changing to the new E type adjuster? Thanks

Anthony

 

[XStretchified650]

Without the locknut I could not put the cover on snug without it turning the tensioner bolt and over tightening the cam chain. There were no successful work arounds except for starting with the plunger setting a bit on the loose side.

I'd experiment with looseness and then see if I could put the cover on, then take it off again to see if the tension adjustment was still good. You can hone your technique but you are basically working blind. In the end you really never know what you have....locknut is the way to go.

I have the type E installed....no real miles on it yet but the cam chain adjusting process is more 'matter of fact' now.

XStretchified