Kawasaki KLR Forum banner

Rear Sprocket Wear - Outside Only

10K views 15 replies 6 participants last post by  Chris350 
#1 · (Edited by Moderator)
Hi Guys, lurker for a few months. Question for you guys.

I have a 2015.

About 7000 kms (4400 miles) ago I changed the front and rear sprockets and put on a new chain. Aligned and tensioned it the best I could and took off on a trip. During my trip I started to notice wear on the outside of the rear sprocket just below the teeth all the way around. There is a little groove now where the chain lands below the teeth. The other side of the rear sprocket is fine. And both sides of the front sprocket are fine.

Alignment of the rear sprocket appears to be correct. I know that over tightening the chain is a common KLR error so I'm careful to not over tighten. If anything it is too loose. Uncomfortably loose for my liking anyways which I assumed was probably correct.

Picture 1 and 2: Showing the wear on the rear sprocket I'm concerned about.
Picture 3: Chain tension with rear tire lifted completely off the ground.
Picture 4: You can see that the teeth are not landing in the center of the rollers. The chain is too close to the bike or the rear sprocket is too far out. When I rotate the rear tire through full 360 its the same picture all the way around.









So my question is what do you think is causing this? Is my alignment wrong? I've read that certain non-stock front sprockets can sit closer to the bike (Not as thick) and that sometimes a spacer is required to align it with the rear sprocket. Any truth in that? That is my gut feeling as to what is wrong. The front sprocket is closer to the bike therefore my front and rear sprockets are not aligned. And no amount of my messing with the rear alignment angle is going to fix this problem, or it will just the move the wear to another surface. I'm a little surprised that the inside of the front sprocket wouldn't have wearing though, maybe because the diameter is smaller therefore less of a force to cause wear?

So what does a guy do here? I'm thinking to remove the front sprocket, measure thickness, compare to stock, and make up the difference with a spacer. (if in fact the stock is thicker).

I checked my stock rear sprocket that I took off the bike (had about 22000 km 13500 miles) and it looks great with no wearing whatsoever but that was run completely with the stock 15 tooth front.

Front: Sunstar 520 Steel Front Countershaft Sprocket 16T
Rear: Sunstar 520 Steel Rear Sprocket 43T
Chain: DID 520 VX2 PRO-Street X-Ring Chain 106 link

Appreciate the comments. Thanks.
 
See less See more
4
#3 · (Edited)
You could have the front sprocket on wrong-side-out, and flipping it would fix things.

It also may be that the wheel is cocked in the swing arm. Don't trust the marks on the swing arm for alignment. That the chain is so obviously off center on the rear sprocket makes me lean toward misalignment.

Either measure from the swing arm pivot on both sides to get the wheel aligned or sight down the chain, adjusting the wheel until the top chain run looks straight. I do the latter, as it is easy to see misalignment in the chain run.

Chain tension looks correct. If in doubt, pull the lower linkage pivot bolt and lower the bike until the center of the counter shaft, the swing arm pivot, and the rear axle are all lined up, then adjust for just a wee bit of slack at the tightest point (which you find by rotating the rear wheel). You'll need an ATV-type lift to do that. Spinning the tire on smooth pavement to find the tightest spot is pretty easy.

Were it my chain I would measure the length of as much of the taut bottom run as I could accurately do and calculate the wear. If the chain has been run flexing sideways it may have more wear in it than the 7000 km would normally cause. Given proper maintenance you should be at about 25% of the recommended wear limit.

Normally one would remove the chain and stretch it out on a bench to measure 100 links to make the math easy, but you have the stock chain with a riveted master link. If you were to remove the chain I'd say just go ahead and replace it, given the trouble you'd go to. We'll do it another way.

You should be able to measure a span of 27 links on the bottom run (the bottom run must be taut! Jam the rear brake on and roll the bike forward to take all of the slack out of the chain, then lock the front brake on. Or, ask the significant other for help. They love to help with this.), but if you have that chain guard stuff on it will have to come off. Each link 15.875mm long, measured pin-to-pin. As the chain wears it is the pins and bushings that wear, so the pin-to-pin dimension gets longer. The acceptable limit is 1% wear, or 16.03mm.

A new chain would be 15.875mm X 27 =428.625mm for that 27 link span.

A fully worn chain would be 16.03mm X 27 = 432.81mm for that 27 link span.

Restated in proper units (hey! there are 300 million of us; how can we be wrong?):

A new chain would be .625" X 27 =16.875" for that 27 link span.

A fully worn chain would be 0.631" X 27 = 17.04" for that 27 link span.

Even though 1% wear doesn't sound like much, when you multiply it over a bunch of links it becomes measurable with a measuring tape.

You can measure your lower chain run and see when it looks like you'll need a new chain.

I only jest about the "proper units", we Americans are converting to the metric system, inch by inch...
 
#8 ·
Update

So a little update. I got around to pulling off the 16 tooth to see what was wrong.

I installed the sprocket backwards. That being said.... when I compare the stock 15 with the sunstar 16 (correct direction) the teeth are not exactly at the same distance but a lot closer now while sitting on the bench. Unless the rubber on the stock 15 sprocket is designed to deform against the case a little? That I don't know. I didn't measure the distance while installed.

If doing it again, I'd probably buy a thin shim to install on case side to bring the teeth out ever so slightly. I've kind of ruined this rear sprocket now so I might install another one over the winter. Until then I'll ride it like this until the snow flies. I might even just install the original rear sprocket as it looks like in good shape.

Correct:


Wrong:
 
#9 ·
Chris350,
Your Steel rear sprocket is fine as is. It will still out-last the chain that is on it. You should have seen the aluminum rear from my KX500 which had a bent lower chain guide.

As to shims, I thing that K#92022-159 is the proper ID. 25mm? These measure .020 inch thick.
 
  • Like
Reactions: Chris350
#11 ·
Thanks pdwestman for the sprocket recommendation, I'll keep as is and just monitor. And thanks for the part number, I believe I read in another post that the ID is 25mm yes.

Chris; thanks for the update...that all makes sense. I agree with Paul that you rear sprocket isn't ruined. The link to the shims that Eaglemike sells is in my first post if you want to make it perfect.

Cheers,
Dave
Thanks Dave, thanks for that link, I did look at that, EM doesn't specify what is included in the shim kit, is it just a few shims of varying thickness? With the Canadian dollar finally reasonable against the USD, ordering from the US isn't nearly as painful these days. It might finally be a good time to order a few things from EM that I've had my eye on.

Do you always run it with the chain that dry? Your chain should not have rust on it

Sent from my SM-G930V using Tapatalk
Is it that dry? I've seen much worse than that! Might be a little, that was after a long trip where maintenance was stretched a little.
 
#15 ·
OK; I was thinking if you were close, you could peruse through my shims.....though all my stuff in in storage pending our move.

I have a friend and fellow KLR owner in Calgary; we just did the Horizons Unlimited Mountain Madness together this year in Nakusp.

Cheers,
Dave
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top