Author Topic: Adjusting the balancer chain  (Read 9553 times)

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Offline berniebee

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Adjusting the balancer chain
« on: November 05, 2012, 07:20:08 PM »
One source of clattering/rattling noise on the XS500 is the balancer chain.
I didn't notice a rattling sound on mine, but the replacement exhausts are pretty loud... so I thought I would check. Besides, I was removing the engine covers for cleaning.

The Clymer service manual is not really clear about this procedure (OK , it sucks) and the Yamaha service manual is laughable too. The Haynes manual is pretty good here but doesn't identify the parts very well. When I read the manual, I thought that the alternator rotor needed to be removed. It doesn't.  Hopefully this post will help you.
 
-To adjust the balancer chain tension you need only remove the left side engine cover. But because it will likely break apart as you remove the cover, have a cover gasket handy.


Once the the engine cover is removed, you will see this:



In the center of the closeup below, notice the nearly vertical line cast into the engine case.  That is where you check the tension. Moving the chain up and down, you are supposed to have 5-7 mm (1/4"of play.
Mine had about nearly 20mm (3/4") of play. NOTE: I remembered to take this picture below only after adjusting the tension, so it looks fairly tight.  Before adjusting the tension, the chain hung quite a bit lower...



Ok, on to adjustment!

The rotor here is removed ONLY for clarity...
What you see in this pic is that the tensioner is at its loosest position and the the chain is hanging loose.
This balancer chain has never been adjusted...



Loosen the allen head screw, then, using large slot screwdriver, move the tensioner so the the slack is taken out of the chain.




After adjustment, the chain and tensioner looked like this.
Again, rotor removed for clarity...




NOTE: This post has been modified. I originally thought that the rotor had to be removed in order to adjust the tension. That is not true. 

Thank you to nickgeorgiou for pointing this out!


Offline fz500

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Re: Adjusting the balancer chain
« Reply #1 on: November 05, 2012, 07:28:13 PM »
Nice work on the writeup! Makes the procedure crystal clear.

Mark

Offline nickgeorgiou

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Re: Adjusting the balancer chain
« Reply #2 on: November 05, 2012, 07:29:13 PM »
I've found that you don't necessarily have to remove the atlernator rotor. I was able to acess it fairly easily.

Offline berniebee

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Re: Adjusting the balancer chain
« Reply #3 on: November 05, 2012, 07:29:48 PM »
To nickgeorgiou:

Doh! (A Homer Simpson doh.) You are absolutely right. I had read the manual so carefully, but didn't look at the engine!
I've modified the post above.

Thanks!

Offline beck

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Re: Adjusting the balancer chain
« Reply #4 on: November 05, 2012, 07:30:15 PM »
Exellent work!
I was about to find a proper tool to pull of the rotor.
Bikeography: Zundap KS 100 *  83'Suzuki ZR50SL * 73'Suzuki GT 380 * 80'Suzuki GSX 750/1100 *
95'Yamaha VMX 1200(119 kwh) *  77'Yamaha XS500 * 78'Yamaha XS650

Offline beck

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Re: Adjusting the balancer chain
« Reply #5 on: November 05, 2012, 07:30:47 PM »
Looks like it is an alternate tensioner-setup with a second tensioner. Mine look like this.
This is pic is not mine thouh.

Bikeography: Zundap KS 100 *  83'Suzuki ZR50SL * 73'Suzuki GT 380 * 80'Suzuki GSX 750/1100 *
95'Yamaha VMX 1200(119 kwh) *  77'Yamaha XS500 * 78'Yamaha XS650

Offline Brad

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Re: Adjusting the balancer chain
« Reply #6 on: November 05, 2012, 07:31:26 PM »
This is great, bernie. I just did mine the other day. Your post was so clear, I did it from memory after reading your post a week or two earlier. Mine was pretty loose!
'76 XS500C - Daily rider. Mostly stock. I actually like Marge Brown.

Offline berniebee

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Re: Adjusting the balancer chain
« Reply #7 on: November 05, 2012, 07:31:57 PM »
Beck,

Thanks for that photo. Is it possible to adjust that second tensioner without removing the side cover? ie: through the removable plug on the the top of the side cover?

Offline marcoxjr

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Re: Adjusting the balancer chain
« Reply #8 on: November 05, 2012, 07:32:31 PM »
Hi!
i tryed to do the operation but my tensioner is just little bit different.....in case the chain is not tensioned after operation, what could be the issue?

Many thanks..Marco

Offline berniebee

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Re: Adjusting the balancer chain
« Reply #9 on: November 05, 2012, 07:33:23 PM »
Hi Marco,

If the chain is only a little loose it will make some additional noise.
If the chain is very loose, it could break and cause serious damage to the engne. Also if the chain is loose, the balancer will be out of phase with the engine, so you could feel more vibration.

It would be best to adjust the tension if possible.
Can you explain what is diifferent about your tensioner, or show us a drawing or photo?

Offline marcoxjr

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Re: Adjusting the balancer chain
« Reply #10 on: November 05, 2012, 07:34:23 PM »
Hello!
 are not currently able to send photos as I have already closed the cover, the differences are that unlike what is shown in your picture, my tensioner is a black plate that joins the upper and lower eccentric. when I rotate for tensioning the chain can not get it to the full tension....my bike is a 1974 TX 500 showed in a picture in Topic: Yamaha XS500 and TX500 Registry...page 3...later i'll try to do some drawing for let you guy un.
derstand well!
Many thanks.....this web site is very very useful!!!!

Well done!

Offline CrouchyUK

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Re: Adjusting the balancer chain
« Reply #11 on: November 05, 2012, 07:34:57 PM »
Hi Marco,

I think the TX500, TX500A and early XS500B's had the tensioner arrangement you describe- as below in the parts book item 24?



Same eccentric arrangement on the bottom idler, but the later deal had the quadrant/screwdriver method..

i think Yamaha were fighting this poor initial design all through the production run.  The second tensioner arrangement pictured in a previous post is a good example!

You have run out of adjustment due to the very small offset on the eccentric idler shaft- the chain has stretched too far for it to work.  If left for too long the chain will stretch further and ride up on the crankshaft sprocket.  it does this because the "wrap" around this sprocket is less than 90 degrees.  Poor design. 

The chain then rubs against the bonded wear strips on the bracket and wears a groove,  Eventually the chain starts jumping the crankshaft sprocket and throws it all out of timing.

I'll post up pictures of my bikes- both were neglected by PO's and both have evidence of the end result- rounded off teeth on the crankshaft.  This means the crankshaft is scrap.

Sorry to scare you, but the balancer chain was one of the reasons these bikes were not popular.  Either replace the chain- they still come up on ebay or from NOS suppliers.  Or possibly extend it's life by finding the additional tensioner arrangement later fitted to the top idler?
1975 Honda CB200T (2) - 1975 Yamaha XS500B (2) - 1976 Yamaha XS500C
1977 Yamaha RD400D - 1977 Yamaha XS500D - 1978 Honda CB550K - 1980 Honda CB400N
1980 Honda CB900FA - 2000 Kawasaki ZX6-RG2 - 2002 Suzuki GSX-R1000K2

Offline bob4717

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Re: Adjusting the balancer chain
« Reply #12 on: November 05, 2012, 07:37:37 PM »
I have a 75 XS500 with a 12-74 build date and I need to adjust the balancer chain.  Took off the outer cover and I have one like the picture from the parts book.  Best I can tell so far is the adjuster on this one is behind the rotor.  Trying to figure how to remove it (rotor) now.  Can I just use the right size bolt?  Anyone have any ideas? Thanks!

Offline CrouchyUK

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Re: Adjusting the balancer chain
« Reply #13 on: November 05, 2012, 07:38:51 PM »
I am still not convinced the rotor has to come off even with the older setup.

Refer to the first photo of this post.  If you have the plate as per the parts diagram you will have the earlier idler bracket and not the one here.  Yours does not have the line cast into it to show where the tension is checked, or the slot bottom left to put a screwdriver blade in.  yours will have "371" casting label, the newer type has "1H2" casting label.  These are the only differences so either bracket can be used for either setup.

Back at the photo above, because the tapped holes are the same both screws that hold the plate on are accessible with the rotor on.  So the plate can be removed.  That just leaves trying to get a hex key into the end of the bottom idler shaft to turn the eccentric. I think it can be done, especially if the starter chain is removed which is an easy job.

It's worth a try if only to quickly see whether the tension can be set.  If turning the eccentric idler just takes the chain from extremely slack to very slack then the rotor is coming off anyway....

1975 Honda CB200T (2) - 1975 Yamaha XS500B (2) - 1976 Yamaha XS500C
1977 Yamaha RD400D - 1977 Yamaha XS500D - 1978 Honda CB550K - 1980 Honda CB400N
1980 Honda CB900FA - 2000 Kawasaki ZX6-RG2 - 2002 Suzuki GSX-R1000K2

Offline bob4717

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Re: Adjusting the balancer chain
« Reply #14 on: November 05, 2012, 07:39:32 PM »
Success!!    I was unable to remove the locking plate from the eccentric until I removed the rotor and starter chainwheel.  Then the locking plate came off (#24 in the parts diagram here).  Adjusted balance chain easily. I can try to attach photos later.  I was able to remove the rotor easily also.  The threads seem to be M16  1.50 pitch on the removal tool.  I found that the front axle from a 1973 Kawasaki H1 is that thread and with a 1/2" spacer inserted against the crank end the axle threaded in perfectly and without too much torque the rotor came right off.
Thanks for the help,  Bob