Question about manual and automatic cam chain adjusters.

Hi Guys. To save me wading through previous posts can anyone tell me if the manual and automatic cam chain adjusters are interchangeable on the XJ650 4K0 models. I have a non-YICS engine with a manual adjuster and I would like to know if I can fit the automatic adjuster from a YICS engine.

 

I'm almost certain they interchange. They use the same gasket so it should bolt right up.

 

Cheers MiCarl. I'm also almost sure the automatic tensioner will physically bolt on. It's whether it will provide the correct tension that I'm not so sure about. If I don't get a difinitive answer I'll just stick with the manual one.

 

Compare them.

"Unlock" both, then press against a package scale and see how much pressure it takes to compress each the same amount.

I'd be interested in those results myself.

 

Fitz, all of the manual adjusters I've used are adjusted with a locknut on a threaded rod. You can place as much pressure on the chain as you like, until either the adjuster, or the chain, fails. Myabe I'm not familliar with the manual adjuster you're thinking of.

 

With the XJ's manual adjuster, by loosening the locknut/bolt you only unlock the rod so the spring(s) can push the plunger against the chain guide. The "manual-ness" is limited to unlocking the adjuster so it can do it's thing. You don't really get to adjust it (unlike, for instance, the SR500 and I believe, most of the XS's.)

In the automatic adjuster, the plunger is pushed by the spring(s) and there is a ratcheting feature that prevents it from retracting. The ratchet can be released to reset the adjuster (or for this test.)

Both adjuster mechanisms are "powered" by the spring or springs on their plunger.

My suggestion (which would answer OP's question) is to compare the pressure (for pressing on the chain guide) provided by each.

 

maybe I am missing something, but I have a 550 w/manual adjuster and a 650 w/automatic adjuster. I just popped them out and they couldn't be more different.


adjusters 2 by bmonkey36, on Flickr


adjusters 1 by bmonkey36, on Flickr

besides, is it really that much of an inconvenience to periodically adjust the tensioner? the service interval for a 550 is 5,000 miles.

CN

CN

 

as long as we're talking springs. your fork springs and clutch springs are sacked out after 30 years, don't you think these adjuster springs are too ?
we won't mention valve springs yet

 

CN, the manual adjuster on the 550s is quite different from the manual adjuster on the 650s; the manual adjuster on the 650 is shorter and I believe it only has one spring.

OP has a manual adjuster from a pre-YICS 650 and an automatic adjuster from a YICS 650 to compare.

Polock, every time I've checked an XJ valve spring's free length against spec, they've been fine. And I don't think these springs are nearly as critical in that respect.

 

Thanks for your input guys. This is all very helpful and it's why I love this site. These are the tensioners in question. As usual you are talking a lot of sense Fitz. As soon as I get chance I'll have a go at trying to measure and compare the relative spring compression and lengths. Hopefully I'll be able to arrive at some sort of conclusion. I notice in your photo CN, that the 550 manual tensioner has a completely different mounting, i.e. the holes are at diagonally opposite corners whereas both of my 650 tensioners have holes transversely co-linear. I wonder if this is a premeditated design feature to prevent the fitting of an incompatible component. I then wonder if, because of the fact that both of my tensioners have a common mounting arrangement, this might mean they are compatible.

 

Measure the lengths from the end of the plunger to the gasket surface and make sure they are similar.

Check the faces to make sure they are similar in diameter.

Loosen the manual tensioner and find a way to lock the release on the automatic tensioner. Face them together and compress about 1/2 the travel (you'll need to find a way to hold them together and not shoot across the room). They should both compress a similar amount.

If all three tests work you should be in business.

You notice I used the word "similar". The tensioner isn't rocket surgery. It just needs to take up the slack on the "push" side of the cam chain and not let it back out. Frankly, in the compression test you can probably hold them - push together - and eyeball the results.

 

I personally found that my auto-tensioner worked a whole lot better when i popped the spring out and the valve cover off and pushed that sucker in with a lever till all the slack was gone off from the cam chain.

I think those springs are a bit weak personally.

 

I've finally had chance to carry out a test to try and establish if the auto tensioner and the manual tensioner exert the same force on the cam chain guide. The simple answer is no. The weight required to compress the manual tensioner to a distance of 25.4mm from the tip to the seating face was 7kg. The weight required to compress the automatic tensioner to a distance of 25.4mm from the tip to the seating face was 5kg. In simple terms the spring in the manual tensioner is stronger than the spring in the automatic tensioner.
Percentage difference between V1 = 5 and V2 = 7

( | V1 - V2 | / ((V1 + V2)/2) ) * 100

= ( | 5 - 7 | / ((5 + 7)/2) ) * 100
= ( | -2 | / (12/2) ) * 100
= ( 2 / 6 ) * 100
= 0.333333 * 100

= 33.3333% difference

 

Here is the thing though - as the crank turns and pulls on the valve train all the chain slack is presented at the rear. The spring only need have enough force to position the chain guide firmly against the slack. It doesn't need to "stretch" the cam chain.

In fact, the manual tensioner might need a stronger spring because it is set statically - when the crank isn't pulling the front tight.

Neither spring has enough force to keep the guide from moving back when the valve train attempts to over run the crank. That's the reason for the lock bolt on the manual tensioner and the cam in the automatic one.

If it were mine, I'd throw the auto tensioner in there. If I didn't hear the chain banging around I'd leave it. It's not like it's a huge job to swap back.....

 

I agree.
A lot of us XS1100 owners have swapped out the original manual tensioner for an automatic one fitted to the VMX or V-MAX.
I'm using them on both my XS11's without problem.

 

Or at least AS tight as it is under load. That makes complete sense, that the manual one would have a slightly stronger spring to be able to accomplish the same end result without benefit of the chain being under full load, and the motor hot, etc.

Those pesky Yamaha engineers, all multiple thousands of them. I have the feeling they had this one handled.

 

All things considered I have now fitted the automatic cam chain tensioner. The engine turns over nicely by hand and I feel confident that it will adequately perform the task required of it. The advantage of this over the manual tensioner is, of course, that any slack in the cam chain will now be automatically compensated for as the engine runs, as opposed to having to periodically adjust the slack out manually. I will report any further developments in 'RobbieRobot cafe racer project in pictures'.
Thanks for all of your input guys.