New 14-48 Sprocket causing chain to bounce

Hey guys! New to the WRR, but really liking her so far. I replaced the chain and sprockets with a new DID Chain and SunStar Sprockets (14-48) The problem I have ran into is now the front sprocket now makes a bit of a metallic grinding noise and the chain is bouncing quite a bit on the top run when going down the road slow or fast. Thanks for all the help

gnarlynate wrote:

I replaced the chain and sprockets with a new DID Chain and SunStar Sprockets (14-48) The problem I have ran into is now the front sprocket now makes a bit of a metallic grinding noise and the chain is bouncing quite a bit on the top run when going down the road slow or fast.

Sounds like a frozen link in the chain; did you use a link connector or a rivet one?

Put the bike on a center stand, engine off, neutral gear, slowly rotate the rear wheel observing the chain as it goes over the sprocket: do you observe any kinks in the chain?

Is the chain slack correctly adjusted?

I used a clip style master link. I have always had really good luck with them on my bigger bikes.

I put this beast on the stand and did just that. The chain rolls and bends perfectly. No binding or pinching, but when I turn the bike on and drop her into first gear even at idle the chain bounces on the top section. Going down the road it does it as well but at a higher frequency.

I put on the new chain and sprockets then adjusted the chain. After I rode the bike for about 150 miles I readjusted the chain to what the service bulletin showed. 13mm from the swing arm. Never seen a chain bounce like this before

Check the alignment of the sprockets with an alignment tool like this one:

https://www.revzilla.com/product/motion-pro-chain-alignment-tool

The marks on the adjusters aren't always perfect and an out of alignment rear wheel could cause this.

gnarlynate wrote:

After I rode the bike for about 150 miles I readjusted the chain to what the service bulletin showed. 13mm from the swing arm.

Where did you get this number? User Manual (Page 6-30) states that chain slack should be between 38 to 48 mm.

I think you are talking two different ways of measuring slack. The owners manual says to measure down from the swing arm at the midpoint to the top of the chain while pushing the chain up with 50 N of force. That measurement should be between 8-13mm. Personally I would go closer to 8 (looser) than 13 (tighter)...

I think you are referring to the delta between up and down of the chain at the midpoint, which is the more typical way of measuring slack, but not how the owners manual says to do it...

johnkol is right. There are 2 different methods. I went with what was in the manual which is 8-13mm from the swingarm. I'm at around 10mm. I figured I'd shoot for the midpoint just to be on the safe side. Even with more slack it still bounces about the same.

BillMoore I moved the rear wheel position a bit to the left and a bit to the right while I was idling in first gear on the stand with the alignment bolts. No change in the chain bounce. I used a laser level to see how the sprocket aligned with the chain, and it looks dead on forward to aft.

Apparently the chain slack adjustment method must have changed for later model years; mine is a 2008.

In any case, when you had the bike at the center stand and the chain was jumping, was it jumping at the rate of the front or the rear sprocket? Or was there no correlation with the sprockets?

I just noticed the part about the "metallic grinding noise"... Did you by any chance try to mount the front sprocket cover? Or are you using an aftermarket case protector? I know the stock cover won't fit with a 14 tooth sprocket (you can make it work by just using the outer cover and the metal spacers from the inner piece, but this gives you zero case protection). I'd try to figure out what is making contact with the chain to produce that grinding noise.

johnkol: Mine is a 2008 as well. From what I saw in my online manual you can use either method, but the 8-13mm supersedes what was in the manual. 6 in one half a dozen in the other is my thought process. The method measuring from the swingarm to the chain is just easier to measure to me. The other method is what I have done on my other dirt bikes.

No correlation between the sprockets was apparent. More speed of the engine... When accelerating the chain smoothed out but when at a constant speed it would start to bounce again :(


BillMoore: You are right. I had to use the outer cover and the metal spacers from the inner piece. I didn't realize the stock parts wouldn't accommodate the larger front sprocket. I have a chain guard-case protector ordered but she is still in the mail. I dont see anything right off that the chain looks to be grinding on... I only hear what sounds like metal scraping when riding... Maybe that noise is from not having the sprocket inclosed fully like before? Any thoughts?!

Weeeeeell fellas I talked with our Yamaha shop here in OKC and they said going to bigger sprocket on the front and rear will make the chain sound different as well as bounce a bit more. Makes sense since the angle of the dangle has changed. One mechanic rides a WRR and said his did something very similar on the top run, but only under heavier acceleration which is opposite than me. Mine bounces when at a steady speed... Anyone else ever have the same experience? Much thanks amigos!!!!!

I'm running 14-50, and I didn't notice any change in sound, definitely not any grinding sounds, and I don't have any bounce...

It really sounds like youre lugging the engine too much, try same gear with more speed, or test by going a gear lower.

Weeeeeeeell Jens Eskildsen its true we have to rev these lil guys pretty hard. I mean they will take it no problem but this issue seems like a constant bounce not just every now and again.

Question... Would a rear 48 tooth sprocket for a YZ250F Fit the WRR? I'm looking to troubleshoot to see if the sprocket I got is bad. A buddy said I could use one of his from his YZ for a test run. Looks like the same sprocket

gnarlynate wrote:

I had to use the outer cover and the metal spacers from the inner piece. I didn't realize the stock parts wouldn't accommodate the larger front sprocket. I have a chain guard-case protector ordered but she is still in the mail. I dont see anything right off that the chain looks to be grinding on... I only hear what sounds like metal scraping when riding... Maybe that noise is from not having the sprocket inclosed fully like before? Any thoughts?!

I have the exact same gearing, 14-48. I have the Zeta case guard, and the clearance between it and the chain is 2mm at most; the chain does not contact the guard when I rotate the wheel by hand, nor does it contact it at any other instance. So if you don't see anything touching when examined closely at very low speed, then nothing should be touching at any other speed.

Idiot check: the chain is a 520, right?

johnkol This gearing is pretty close to stock and supposedly it stops the chain slider from being worn out to quickly. I also like the idea of tossing a 13 tooth front sprocket on for some real dirt work. I dont see the chain touching the spacers or anything else when I spin the wheel by hand. I dont see the chain bouncing when I rotate the wheel by hand either... Only when I turn the bike on and drop it into gear does the chain bounce. Any ideas on that?

Good call on the idot check man! I double checked and the box says 520 and so does the part number. That was my first thought lol

gnarlynate wrote:

I put this beast on the stand and did just that. The chain rolls and bends perfectly. No binding or pinching, but when I turn the bike on and drop her into first gear even at idle the chain bounces on the top section.

How about posting a video of that?

jotis how can I Post a video on here? Forgive the ignorance... This is my first forum Is there an app for that? Seems a forum is a little less user friendly than Facebook or other social media platforms. The video would definitely be a great way for me to show you guys whats happening

How does it look at the lower rear chain guard? Any contact there?

BillMoore No contact on there. Doesn't touch top bottom or side. I looked on youtube and saw a few other people had similar problems when their chain was new on different bikes like V-Strom 650's and Bandits. Some people had success when they loosened the chain quite a bit. I think tomorrow I will loosen this bad boy to its max limit and see if that helps. Thanks for all the help guys!

PS Im trying to load a video on youtube now about the chain... Its about a minute long but is taking foooorever to load :(

That noise coming from the front sprocket is the chain rollers contacting the sprocket.
Normal noise.
If you have ever seen the original Yamaha front sprocket, you saw rubber dampers stuck to each side of the front sprocket.
They are there to help silence that noise.
Those rollers make noise because they are not sealed by any O-ring or X-ring and merely bounce around.
Lubing the chain will immediately reduce the noise because the lube gets on top of and under the roller and cushions the metal-to-metal contact.

Chain motion looks normal to me.
That will happen without a load being put on the chain (I highly doubt that happens when you are on the throttle and climbing a hill).

I have found out the hard way that if you intend on keeping the chain slack near the minimum specification shown in the Owner's Manual, you will be making constant chain adjustments.

Yup, seems perfectly normal.