WR250f "Normal" Chain Noise?

Ok, after riding a CRF230 last year (I know, cottage bike) I got my own WR250f this year. Everything seems to be working fine, but I had the chance to ride it this past weekend and there is quite a bit of noise coming from the chain, something that I never heard on that Honda.

I have new front sprocket, almost new rear sprocket, chain is within the yamaha "still good" limits, cleaned and oiled in engine oil. The roller and rear chain guide are new, the one on the swing arm shows some wear.

What is considered "normal" noise coming from the chain? I have the 3 finger slack as per the manual (slightly more than 2", see pic).

Any tips and tricks aside from the silicon under the front chain guide? Does that actually do anything?

Any better way of finding the amount of slack needed?



If you mean the slapping noise coming from the chain slider (Yamaha parts catalogues call it a seal guard), that's what they do.

Some silicone sealant under the chain slider helps cushion the noise, but won't completely eliminate it.

Me, it doesn't bother me much.

It's pretty normal. The silicone will definitely help, put it on the top and bottom of the swingarm under the chain slider.

Thanks, I just ordered a new chain guide and I will use silicon under it.

Is the 3 finger method good enough? I read about removing the rear shock/ spring for the proper chain slack adjustment, is that really needed?

How do you know if the chain is too tight?

Compressing the rear suspension until the front sprocket shaft, swingarm pivot shaft, and rear wheel axle are all aligned is when the chain is at it's tightest.

If you don't want to remove the shock but still want to check this, sit on the seat well to the rear of it and then check the slack.

If there is none, your chain is too tight.

I dunno bout every bike, but least on mine i do believe it says 1.9-2.3" with the wheel suspended. Which would bring that number down under bike weight. Does your manual say on the ground, or on the stand for the "2 inches"?? Pic appears to be on the ground, why I figured id throw it out there.

I felt like I had mine too loose, because in whooped out areas where my wheel would unload entirely, i was hearing a ton of chain slap. When i checked it wheel suspended it, it was above 2.3". Tightened it up a little, and on my last ride I didnt notice it anymore.

Edited by J_WR2fitty

Good points. I will try to compress the suspension to that extent, not sure if I can do it with the shock on. Checked the manual and to remove the rear shock you have to take apart half of the bike. I understand you only do that once but...

Manual is not specific in whether the bike should be on the ground or stand, I assumed they talk about the bike on a stand. And if that is the case I should tighten it a bit. Manual sails 1.9 to 2.3 and on the ground I am close to 2.3

The spec shown for chain slack in the Yamaha Owner's Service Manual is with the rear wheel unweighted (bike up on a stand).

My experience over the years with chain slack:

Most people (including life-long motorcycle mechanics and techs) will tend to run chain slack too tight because less slack "looks right" or "looks safer" to them.

I believe it's to do with a fear of the chain derailing from the sprockets, a fear of too much slack causing a lot of noise from the chain slapping around, too much slack causing a sloppy delay on throttle response, or some other concern.

If somebody comes from a street bike background where the shorter-travel rear suspensions specify less slack than a dirt bike with 12 inches of rear suspension travel, it's even more so.

One recent example is when I sold one of my bikes to an experienced motorcyclist and ATV motocross ex-racer.

The very first time I saw him ride my ex-CRF-450X to work a few days later, the chain was adjusted so tightly you could probably play a tune by strumming it.

This is a guy who is experienced, not a rookie.

Myself, once the chain is adjusted to where it should be in order to allow some slack through the swingarm's arc, I leave it alone and rarely need to make an adjustment.

This means that it will tend to gain a bit of slack after the first ride after the afjustment, but after that and after it relaxes to it's "happy zone", it stabilizes and stays put.

For a long time.

I have found that if you intend on keeping the slack exactly within the specs in the manual, you will be constantly adjusting it and prematurely wear the chain out.

Believe it or not, many bikes I've owned list a chain slack spec that is probably OK in the clean environments of the street (or engineering laboratory back at the factory), but out in the dirt with dirt being caught up between chain and sprocket teeth on a regular basis, the listed slack spec can and does become too tight, and if you try to stay within even the loose side of that spec, you'll be constantly adjusting.

The exception is if you are using a non-sealed (non O- or X-ring) chain, as riding off-road in the dirt, water, and mud will wear these chains much more quickly, requiring more care and feeding by nature.

Edited by YZEtc

Myself, once the chain is adjusted to where it should be in order to allow some slack through the swingarm's arc, I leave it alone and rarely need to make an adjustment.

This means that it will tend to gain a bit of slack after the first ride after the afjustment, but after that and after it relaxes to it's "happy zone", it stabilizes and stays put.

For a long time.

I've found this true for the non-sealed chains as well. I have a O-ring ready to go on for the next chain, but running this one until it needs replaced. Many don't realize it is also important to rotate your wheel and check slack in multiple spots as sprockets do not necessarily wear evenly, and will usually have a spot tighter than the rest.

Thanks all, great info. I have bit the bullet and bought a new chain slider to start with, the old one was really worn out. As soon as I installed it it made the chain tighter.

Then I dropped the rear suspension by removing the botton shock bolt. Very easy to do and worth doing to figure out the initial adjustment.

I have pics of the new chain slider installedNew Chain Slide.JPG

Shock bolt removed SuspensionBOLT.JPG

And rear wheel dropped Wheel dropped.JPG

I will post more pics once I'm done.

My conclusion after all this exercise is that the 1.9-2" slack when on the stand is the appropriate chain tension. Once the chain slide starts to wear out, you will have more slack in the chain.

Here is the tightest spot Tightest.JPG

The slack at the tightest spot, I would say about an inch Tightest slack.JPG

When everything was said and done I got to this 1.9" slack Current Slack.JPG

I also found this interesting posting that pretty much sums up the method that I have used


Thank you all, this is an amazing forum

I use 3 fingers just like you showed in your first post...

Got to ride the bike a couple of times already, no more chain slap or chain noise in general. My conclusion is having good chain slide/ guide and proper chain adjustment, + using silicone under the slider=problem solved. :thumbsup:

Edited by meWR250f

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