New sprocket, old chain

[CraigD426]

Ok, so I have about 8500 miles on the original chain and sprockets, I was wanting to do the 14t front. Is it a bad idea to put a new sprocket on a chain with that many miles?

[Mr Earl]

I did pretty much the same thing, and there were no problems.  If your chain is in good shape and you maintain it with cleanings and lube, IMHO there's no reason not to do what you suggest.

In fact, 5000 miles after the 14-tooth sprocekt went on, I got a new chain (a few sticking links) and didn't replace either sprocket! 

[corndog67]

I always, always, always put a new, top of the line DID chain on with new sprockets.   I've used used chains before that looked fine, and when they broke, took out the engine cases.   I've also had problems with Tsubaki, and RK chains, neither of which would back their products.   Soooooo, I use nothing but DID ERV chains.   

Don't put old chains on new sprockets.   You could get lucky 5 times in a row, but is it worth tearing everything down, have the cases replaced or welded, and putting it back together to save $100?   It's not worth it to me. 

[Desmo Demon]

Do as you want, because you'll get all types of advice and opinions.

For my personal experience with what you want to do....

I went the first 11k miles with the OEM chain and sprockets on my ST2, then installed only a 14-tooth front sprocket. At 18k miles, I replaced only the chain. Replaced all of them at 36k miles. This means that the original rear sprocket saw 36k miles with two chains. 

On a slightly different note, we bought our M900ie with only 10,500 miles on it. I'm guessing the stock 520 chain and sprockets wore as quickly as my 748's did (OEM set was absolute trash in 11k miles). I prefer to run 525 chain and sprockets for longevity. I converted my 748 to a 525 and wish I could with the Monster, but it looks like the '01 M900ie sprockets only come in the 520 size.

So.....if you are running a 525 setup, you may be fine, but if you are running a 520 setup, you may have some fairly well worn chain and sprockets and putting a new 14-tooth sprocket on the bike may result in only a few thousand miles before you need to trash the whole setup. I prefer 525 and 530 chains over a 520 for street use, any day of the week.

[the_Journeyman]

I left my original front sprocket when I change the rear sprocket & chain on my M750.  It had 27,000 miles on it.  I'd say unless there's noticeable "hooking" of the teeth of the sprocket you're not changing you're just fine ~

JM

[ScottRNelson]

I put a new 14-tooth front sprocket on the old chain on my ST2.  I figured that it wasn't a problem, but it started breaking rollers on a chain that otherwise still looked good.  Once you lose a roller it's going to put uneven stress on the sprocket teeth and pretty soon you'll start having other things break.

I replaced it all with a new chain and two new sprockets.  But at least I then knew the optimal gearing for that bike.

I was ready to discount the opinions of those who say to replace everything together, but they might very well be right.

I used the "old" rear sprocket with a new chain on that bike last time, since it didn't have that many miles on it when the chain started to stretch unevenly.  Now I'm hoping I don't have an early demise of chain and sprockets from doing that.