Chain suddenly stretched?

My chain seems to have suddenly gone from fine to crap, tell me why.
At the beginning of last season I replaced the chain and sprockets with an EK 530 MVXZ. (thought this was a decent brand) I always do my best to keep it clean,dry,and lubed about every other tank of fuel with Dupont chain saver. The chain always looked like new and only needed one slight adjustment at about 1000km. Now it has maybe 5000km on it and has recently started loosing its grease past the o rings, and has a badly stretched section that can't be properly adjusted. There are no stiff links and no rust. I do sometimes downshift hard, but not to the point that the rear wheel hops around. Just as a comparison, i mounted new PR2s at the same time as the chain and they are only half way wore out. This can't be normal, what am I doing wrong?

 

Yes but wouldn't it wear gradually and evenly? When turning the wheel on the centrestand the slack changes dramatically. Until lately I was always able to keep constant slack of about two inches up and down on the bottom of the chain.

 

Ya the sprockets look like new. I think I'll flip them and the try another chain on them. Was EK a bad choice? Is DID any better?

 

It does sound like running chain too tight--are you a big fellow, how much do you weigh? The rear suspension travel causes the chain to tighten as it gets loaded. You want to adjust it such that even when fully loaded in a hard corner, then you still have a slight amount of slack in the chain--so it takes a helper to load/measure, etc...

When you said the chain looked like new, did you mean that the rollers were all clean and shiny? There is two places that chains wear--inside the rollers at the pins, and outside the rollers at the sprockets.

i don't know about dupont chain saver, but i use 90 wt gear oil and keep that thang lubed up all wet like mary-jane's rotten crotch just short of the point of drippin on the tire...

 

I'm no expert at all, but two inches sounds more on the loose end of the scale rather than too tight.
John

 

Two inches is definitely too loose.

 

Poor Mary-Jane, she must have a soggy crotch. Makes life easier for insertion though :stripper7: On my Ninja 5, I noticed that I have excess slack (more than I run.) Gona do an adjustment today.

Chain Law: Adjust when cold, lubricate when hot. Simple right? One thing to bear in mind, every chain no matter brand, bike etc if its not brand new, ie (some miles, is gona have a tight spot, not to be confused with Mary-Janes wet spot.) So, once you rotate the rear wheel a whole bunch of times while checking for slack on the bottom of the chain, you will discover the tight spot. It is important to adjust tension of this spot, not other looser spots.

EK is an excellent chain, just like Mary-Jane sed. :thumbsup:

 

I've always wondered what causes a chain to have an apparent tight spot. It seems unlikely that the chain would wear more in certain sections more than others, or that the sprockets would wear more in certain areas than others as they rotate. Is it possible that some links get stiff (I said stiff....huh,huh, huh) and don't straighten out completely making the chain shorter in those areas as it rotates through it's cycle? Educated opinions gurus?
Thanks
John

 

Occam's razor.. re-adjust the chain and use a torque wrench on the pinch bolt.

If you are experiencing anything close to wheel hop on downshifts, this is not only hard on the chain but the whole drivetrain. IMO, your downshifting technique needs work.

 

I just replaced chain and sprockets, my chain had two tight spots, after I took it off, I could see the rust dust in those areas.

 

lex parsimoniae

huh? Don't use a "torque-hammer" what ever you do

 

Don't really know what may have caused you problems. Others here are more in the know than I am. But I have used a few DID chains and have used DuPonts Chain saver for a few years now and love them both. I see you live in London. Do they use as much salt on the roads there as they do in the GTA and MOntreal area. If so, and you are proned to get out earlier in the season, hidden rust could very well be an issue.

 

i think you will find that 2 inches of chain slack (+/- 1") while totally topped out on the center stand will be too tight when fully loaded in a hard corner. You don't want a tight chain in a corner--it affects the suspension and handling as well as wears out the chain. Too loose is better than too tight. i've been easily getting 25k or more miles on chains by running them on the looser side rather than tighter, and keeping them slathered in gear oil. i guess one man's tight is another man's loose, but i ride hard in the curves and tune to use the entire suspension stroke, and adjust the chain so it doesn't interfere with the shock travel...

 

Thanks for all the replies, to answer some of the questions...
I'm 6'4", 210lbs.
When I said "like new" I mean it was always kept clean, wiped down with a rag and a little wd40, and lubed with chainsaver. It never had a chance to accumulate dirt or grit.
The 2" of slack is on the centrestand. I have a 5mm spacer in the rear shock so the chain seems to tighten quickly in the first inch of travel. Any less would be too tight.
The pinch bolt has always been properly torqued. The eccentric doesn't slip. I don't think I have ever down shifted hard enough to damage the chain or if that's even possible.
Yes they use alot of salt on the roads here but my bike doesn't see it and I seldom even ride in the rain.

After thinking about it I'm a little suspicious of the Dupont chain saver. The problems started this spring about the same time I started a new can of it. I remember someone saying that they changed it or maybe the stuff we get in canada is different.
Any thoughts?

 

is that going on your viffer or the DR?

 

A guy on the FB forum says that he's had problems with the master links on his EK 530 MVXZ chain. Says he has to "re-rivet" the master every 8K or so miles.