Chain and Sprocket failure??

Hey boys,

I have had my yz426 for about 5 months now. Usually riding once a week. I changed my chain before I even broke it in (to a DID ERT). I religously clean, tighten and lube my chain. After this weeks ride, I noticed some serious wear on the rear sprocket, a couple of the ends of the teeth have busted off. Today I picked up one of those Stainless rear sprockets from Krause Racing. Two things I have noticed.... One was that the sprocket they gave me does not fit snug around the hub like the stocker (and any other I have seen). There is about .05-.08" gap between the ID of the sprocket and the OD of the hub flange. The bolt holes line up fine. The second thing I noticed was the hard spots in my chain. There are about a half of a dozen hard to move links in the chain, could this be bent pins? I have always replaces chain and sprockets in sets, but I figured since the chain is pretty new I would be fine. Now I am starting to wonder. I have been setting my chain tighness around 1.75" with a pretty good tug. With a couple of guys sprockets folding, I am starting to agree you guys thinking that the manual is setting a too tight of chain spec. I would hate to scerw up a new $120 sprocket.... Any suggestions? My riding style varies from hill climbs, playing on MX tracks, sand, and a little bit of everything else. The chain is setting in a bowl of kerosene for the night, thinking maybe some sand or something might work itself out.



[This message has been edited by Tim (edited 09-06-2000).]

Hi Tim

Same probleme. I use parafien, dont know what they would call it there by you. People use it in lamps that works with a wick. This looses the links quick quick. Please dont use gas cause it KILLS the O'rings in the chain. Once they go hard you can buy a new chain. I normally do it after every second or third ride. Hell it last lots longer this way.

Hope it helps

Greetings from SA



i did the following to my roadracer, you may find it a little crude.

take the sprocket, a medium chisel & a light hammer over to a vice plate/anvil.

make wedge marks right on the edge all the way around the ID of the sprocket. try it on the hub. it should now need a tap on. if still loose tap a bit harder.

next thing to check is the free spinning of the sprocket. with no chain on the wheel, spin it. take a scribber & mark the sprocket as it spins near the teeth. get a friend to g-e-n-t-l-y spin the wheel while this happens.

you may find that the rear sprocket is running eccentrically & that your tight spot is infact the sprocket.



Buffalo is hard on bikes. I run my chain a little looser then spec's. I installed a Tsubuki (sp?) o-ring chain after one ride and haven't had a problem. The best thing you can do for your o-ring chain is, LOTS of WD-40 or like penetrating oil. Spray it on before you load. after you ride and after you wash. I didn't wash my bike once after a trip to Buffalo and I'm still working all of the crap out of it, point is if you are going to ride there, clean your bike afterwards.

But most of all, keep it rubber side down and have a good time.

I'm curious. Has anyone replaced the bolts with a better grade of hardened bolts? I would have thought that the OEM bolts should be good enough but that may not be the case. Of course I would have thought the OEM chain was at least somewhat good, it turns out that it sucks.

This is my first new dirt bike and I'm getting a little gun-shy.


Yeah, I think you bent the pins in your chain. I have done this before but I didn’t consider a too tight chain to be the culprit. I surmised that the narrowed and hooked rear sprocket focused the force on a smaller section of the roller and pin thus bending the pin. But an overly tight chain could have also played a part.

I’m sure you’ve heard this before, but I always replace, at the very least, the rear sprocket and the chain (and often the countershaft sprocket as well) at the same time. A good o-ring (Regina is my personal favorite) mated up to that stainless sprocket should last a long time.

I have an assortment of different sized aluminum sprockets (Renthals) and one stainless Sidewinder. It fits perfectly. Personally, for the kind of money a stainless sprocket costs I wouldn’t put up with one that didn’t fit snug against my hub. The rim on the hub that mates to the ID of the sprocket may provide important additional support. A few on this forum have already ruined some hubs when the sprocket ripped the bolts out. IMO you should raise some hell and get your $$ back from Krause for their ill-fitting sprocket.

As for chain tension I just use the three finger rule (three fingers between top of swingarm at rear of arm/chain guard and chain), and have only had one chain go “bad” on me, and that was after several days with a 10 paddle tire at Glamis with a bottom of the line DID non-roller chain on a worn and hooked sprocket. I know o-ring chains are expensive but I think they are worth it. I don’t know how or why exactly but in my experience they outlast normal chains at least two to one.

If your gonna shell out big bucks for a stainless sprocket then:

1) you should demand that it fits perfectly

2) you should splurge for a good o-ring chain

Then you will have one less thing to worry about…

Hope this helps!


Get to the cause. Working around a problem will not solve it.

As for the chain tension, don't risk it. Run it at 45 mm or up to 50mm. Or at least take the time to measure the tension when the swing arm is at it's full length.

And I'm suprised by how many people out there are not running chain lube simply because they don't think o-rings chains need it.

Lastly, double check to make sure the chain you're using is rated for your bike. Don't assume that the parts guys are always right.

Good luck.


Thanks guys!

I talked to krause and they assured me that the fitting tightly does not give any additional support or stability. Without sounding like a salesman........the stainless sprocket has to be much stronger than the aluminum one. This thing is a monster compared to the stocker (sunstar)!!

He also talked me into the latest and greatest chain. Close to 14,000 lbs tensile strength. The side plates are stainless also. Not cheap by any means, but very beefy. I do think they are overpriced, but the DID (ert) I got less than 5 months ago is pretty beat. I probably should have gotten the o-ring now that I think about it, but I am sure this chain is much more than the one I have now. I will try to run the chain a little looser than normal. See what happens. Anybody have any horror stories about loose chain disasters?

Thanks again I will report my findings this weekend :)

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