A question about chains and sprockets

[.chris]

24,000km later my ktm needs a new chain.

Now I know its best to replace the chain/sprockets all at the same time.
But to my eyes my sprockets still look pretty good (both stock KTM steel sprockets).

On the other hand, the chain is rooted, there are a few tight links, and the links next to the tight ones are very loose.

Would it be worth just going with a new chain?

It is $180 for a new chain (520 Renthal/DID 520) vs $350ish for a new chain/sprocket set.

Thanks in advance for your enlightened advice.

[MSTRS:Me]

At that mileage, it would be a mistake to only replace the chain.

[NighthawkNZ:Me]

Its recommended to replace all at the same time...

If you just did the chain the old sprockets can wear out the new chain quicker...

[Drew]

I would get the chain, and then put it on the sprockets to check how much movement is in it. But I'm always broke.

If you have the money to do the lot, then do it.

[onearmedbandit]

Without a doubt, if you can afford both do it.

[pete376403]

Rear sprockets *usually* last about three times the life of front so you should replace the front at least.

Observation on chains - all manufacturers offer sealed chains be it O ring, X ring or some other profile. However when I replaced the chain on the KLR (and this was a first for me as I've had a shaft drive bike previously) the side plates were nice and tight, as befits the O ring, but the rollers were very loose on the pins, as there is no method of sealing the grease in the rollers. Does this imply the side plate seals are more of a marketing ploy than anything else?
Chain was lubricated every time the bike was ridden, often several times daily. Only lasted a little over 21000k

[MSTRS:Me]

Surprised your chain lasted that long, if sprocket/s not replaced.
Would you put old rings on a new piston? And why not?

[Taz]

Chris - If the sprockets look that good just replace the chain.

[bart]

I recently bought a new chain and rear sprocket (17000km). The front sprocket was virtually new so didn't bother with that. Anyway, once I compared the rear sprockets, I realised the original rear was hardly worn. I put on the new chain, and now have a brand new sprocket hanging in the shed for 17000kms time.

If it ain't worn, why change it. You might loose a couple of thou out of the new chain, but who cares.

[warewolf]

But to my eyes my sprockets still look pretty good (both stock KTM steel sprockets).

I would say your eyes deceive you. Unless you really know how to judge the wear - and it's subtle - there is just too much risk that the worn sprockets will kill the new chain in very short order. You either waste money replacing sprockets prematurely, or you waste money prematurely wearing a new chain on old sprockets. Your call.

You've had a bloody good run out of that set. Either you're very very gentle on the bike, or the 690 must be much less stressful on the drive train than my old clunker. To give you an indication, on my 640A I get 8-9000km per front sprocket, 20+ from a ChainGang rear, 12+ from a KTM steel rear, and about 15K from a good X-ring chain. My regime is roughly new front + rear + chain, then replace front at half-way. However the OEM set was steel front, good x-ring chain and alloy rear. That set lasted just over 6000km because the alloy sprocket wore way faster than I expected and took out the chain and front before I could replace it. It looked slightly worn when I left Wellington but everything was completely fcuked at the end of the day in Auckland.

If you're too tight to replace it all now, get a really cheap short-life chain to finish off the sprockets, then replace the whole lot later. Or put a whole new set on now, and keep your reasonable-condition sprockets for occasional use as alternate gearing.

[clint640]

My regime is roughly new front + rear + chain, then replace front at half-way.

That is what I do.

Chain gang rear sprockets are bloody good, I heard a rumour that they had started making them again? But if you got 24K outta the std one thats real good, I'd get another if the price isn't crazy.

Cheers
Clint

[MSTRS:Me]

I would say your eyes deceive you. Unless you really know how to judge the wear - and it's subtle - there is just too much risk that the worn sprockets will kill the new chain in very short order. You either waste money replacing sprockets prematurely, or you waste money prematurely wearing a new chain on old sprockets. Your call.

+1.
If all you are expecting out of chain or sprockets is <10,000kms, then no real harm in not replacing together. But to get maximum life from all 3 parts, they must bed in together. Potential longevity is destroyed by mixing new/worn. In the case of chains/sprockets, it takes very little mileage for wear to get to the point where changing one component leads to accelerated wear on all three, as each sprocket tries to get the chain to conform, and vice versa.

[.chris]

That is what I do.

Chain gang rear sprockets are bloody good, I heard a rumour that they had started making them again? But if you got 24K outta the std one thats real good, I'd get another if the price isn't crazy.

Cheers
Clint

The stock ones are pretty cheap, $100 for 45t rear, $40 for 15t front. much cheaper than any other options which must be a first for KTM power parts.

I was thinking of getting an ironman rear sprocket, but they are about $200 which seems rather expensive compared to the ktm ones.

I think it is the combo of the slipper clutch & the cush hub that has made my sprockets last so long, but I think because of them the wear might be pretty even, which makes it appear less worn.

Just ducked into my local shop, and they can get some generic sprockets to fit the 690, even cheaper than the ktm ones, and I don't have to wait 3+weeks.

So full set it is. They have recommended a EK 520MVXZ chain, which seems ok to me.

[clint640]

The stock ones are pretty cheap, $100 for 45t rear, $40 for 15t front. much cheaper than any other options which must be a first for KTM power parts.
.

That's not too bad, the chain gang rear sprocket I had was $170 delivered, I got 24K km out of that. I might try a KTM steel one next rather than another of the generic steel ones I have on at present.

Cheers
Clint

[warewolf]

Chain gang rear sprockets are bloody good, I heard a rumour that they had started making them again?

Yep, got their hands on some more high-grade steel. And there is now supposed to be an Auckland distributor.

The stock ones are pretty cheap, $100 for 45t rear, $40 for 15t front. much cheaper than any other options which must be a first for KTM power parts.

I was thinking of getting an ironman rear sprocket, but they are about $200 which seems rather expensive compared to the ktm ones.
...
Just ducked into my local shop, and they can get some generic sprockets to fit the 690, even cheaper than the ktm ones, and I don't have to wait 3+weeks.

So full set it is. They have recommended a EK 520MVXZ chain, which seems ok to me.

KTM sprockets are cheap because all the adult bikes (singles) use the same rear sprockets. The LC4 fronts are unique but the SX & EXC bikes use a common front.

Chain Gang rears are slightly more expensive to run than KTM steel, IME: cost slightly more than double but last slightly less than double. But they are bling! bling! KTM fronts are very good - last nearly as well as Chain Gang but cost about half. From memory the ironmans, stealths and chaingang all last roughly the same. Also Chain Gang's fronts are imported high-grade European stuff, not made by them.

Given that KTM OEM steel is reasonably priced and lasts well, I wouldn't buy anything cheaper, and certainly wouldn't run a good chain on cheapo sprockets. Not only do you have to match the initial wear of all 3 components, for maximum life you also should match the quality so they all wear consistently.

At the moment the aussies are saying the DID 520 x-ring ATV chain is the hot ticket. That'll be my next one, and soon, as I'm up for a new set now.

PS if you reckoned your sprockets were good enough for another chain, then you can wait 3 weeks for the next set to arrive...