Problem with chain slack

[jesse0192]

I went out to clean my chain today and finally figured out what's causing the strange "pulsing" vibration i've felt for the last week or two when i'm riding.  As I rotate my tire around, there is one point where my chain slack is pretty loose, about 1.5" or so... and as I rotate it farther, i hit the other extreme, and the chain has about 1/4" slack.  I eyeballed the rear sprocket (wondering if one side had somehow worn down quicker than the other) and it's perfectly round.  I dug a bit further to the front sprocket, and it's also doing just fine, all even.  The rear wheel is adjusted just right, i've ridden about 500 miles in the last few days since I last adjusted it and the bike handles perfectly (as far as the rear wheel alignment, i mean).

I'm certainly no mechanic, but it seems like the only thing left is that my chain has "stretched" unevenly.  The chain is an RK (520 gxw iirc) with around 8-9k miles, and both sprockets are about 1 or 2k miles older than the chain.  I know the 520 chains tend to be relatively weak, but i adjust and clean it pretty regularly, and all the seals and everything seem to be in good shape.  Any suggestions?  

[photomd]

Replace the chain and sprockets. They're wear items and if you get a good set, keep it clean and lubed, you'll be good for 20-30K miles. IMHO, once they start to wear like that, they get worse pretty quickly...in say 2K-4K miles.

BTW, when I had a VFR, I put the RK chain and sprockets on that were waranteed for something like 20K miles. Mine went south before 10K twice. I switched to DID chains and they seem to last much longer, IMHO, my 0,02, yada, ,yada, yada.  

[bomber]

Chains do, in fact, wear unevenly.

Yours' sounds like an extreme example, though -- 1.25 inch variance is big.

Me? I would replace the chain.

You should at least check for wear by trying to pull the chain away form the rear sprocket -- if doing that causes the chain roller (the part that sits in the sprocket valley) to move more than half way out of said valley, you shoudl replce the chain, too.

And, perhaps, the sprocket.

[scottzilla]

I think you may have been running it a little too tight.
You should probably loosen it a little bit as 1/4" isn't much slack.

As for the chain itself, I really don't think you have a problem and should just continue to run it.  A "Stretched" chain won't wipe out sprockets the way a misalligned chain will.
A looser chain allows the rear suspension to work through it's entire range of motion which is a good thing.  Just make it tight enough to avoid any lash and you will be OK.
I think the 520 is fine for an R6.  As fast as the bike is, it's a low torque machine.  Yamaha engineers know what they're doing.  

[bomber]

A "stetched" chain isn't really stretched (we all know)- the diameters of the pins around which the rollers rotate have been worn smaller.

As a result, the rollers are actually different distances aprat thanthey were thwn the chain was new.

This will cause accelerated sprocket wear, though not as accelerated as misalignment.

[jesse0192]

Thanks guys.  I might've exagerated the numbers a little bit, but it's extremely tight in one spot and it's looser than I'd like in another.  I'll probably add a little slack just so that tight spot isn't so tight.  I've heard that DID chains are the best, that's what i'd like to go with next.  I'll replace it all asap, I just wanted to make sure there's not anything catastrophic going on    Thanks guys!

[county]

Chain adjustment is suppose to be done at the tightest point on the chain.

Adjust it to spec at the tightest point and run it till adjustment is used up.

IMO.

[Papa Lazarou]

Even new chains have tight points. But I'd replace. Not worth it jumping off the sprockets or damaging gear box bearings.

what you describe is the need for a new chain. Pulsing is not good.

Now, can we start a chain oil/ best make of chain thread?

BTW, the chain on my Guzzi is missing. Should I be worried?

[bomber]

only if the whirley gig governor isn't rotating at the appropriate speed.

[Papa Lazarou]

only if the whirley gig governor isn't rotating at the appropriate speed.

Ohmigodonastick! The whirley gig  

[county]

Even new chains have tight points. But I'd replace. Not worth it jumping off the sprockets or damaging gear box bearings.

what you describe is the need for a new chain. Pulsing is not good.

Now, can we start a chain oil/ best make of chain thread?

BTW, the chain on my Guzzi is missing. Should I be worried?

Its pulsing because it's too tight.

With the Guzzi, I wouldn't worry about it until you get tired.

[Papa Lazarou]

Thank the Lord.

[raven]

DID chains are the best, I had the same uneven wear and excessive stretching with RK, mostly do to two up touring which loads your chain more then normal as well as 'poor' chain maintenance, you really have to be religious with lube/cleaning.  BUT after I got my DID ZVM2 chain on, I rode 4000 miles two up fully loaded through the Rockies and had to adjust only once! I almost gave up on my bike with all that chain hassle, UNTIL the DID.

These guys seem to have good prices (DID zvm model chains are high tensile strength chains made for higher horsepower/torque)


http://www.whitebuffaloracing.com/shopcontent.asp?type=didchains

[Fav]

I ran a DID Erv2 and later an ERV3 chain on my 02 R1 over 30k miles. IMO, they last long if treated well.....even for a 520.

I just got an ERV3 chain and sprockets for my 06 R1.  

The key, imo....is to not be abusive to the drivetrain.  Clutching up wheelies or popping the clutch is hard on any chain. I don't do it and have never had a 520 on my last 2 liter bikes stretch weird. The EK 525 chain I ran on my 99' Yzf600r didn't do so well.....but I clutched wheelies with it.

[Papa Lazarou]

 Clutching up wheelies or popping the clutch is hard on any chain. I don't do it and have never had a 520 on my last 2 liter bikes stretch weird.

I don;t do it only because I can't. Except by mistake.