Chain Rattle

[07wr250]

Both of our WR's chains rattle when we're hill climbing. Both chains have the proper amount of slack, and are kept clean and maintained, and one chain is less than 3 months old. The sprockets are also in good shape. It just seems that there is a lot of rattling/slapping noise when the engine is chugging. Any suggestions? Or is this common? Thanks guys

[dgcars]

If you are only riding trails, keep the chain slack between 45-50mm. This helps.

[07wr250]

That's a bit tighter than the manual recommends. Will it causes issues with binding?

[dgcars]

I think the manual calls for a minimum of 1.9 inches. For me, thats 3 fingers at the rear bolt on the chain slider.

[moto_ridah]

It's a pretty common occurrence depending on how tight you run chain. Easiest thing would be to down shift.

[yamahakid88]

if you were going uphill you would thing that would put more tension on the chain O_o not less, try tightening it a bit more

[fluffdad]

I had a lot of noise coming from that area on my 07 YZ250F, even my co-riders could hear it while riding on their bikes. I replace the Chain slider and I noticed the difference immediately. no more noise.

[William1]

Yup, chain slider and rollers are the cause (as well as a worn out chain) in most cases. Also running extreme sprocket combos (12/60-Yikes!!!) will do it too.

Chain should be correctly tensioned. To see what is truly correct, you need to move the suspension to the extremes of travel and ensure the chain is not tight and has some up and down left. But nearly no one does this. Three fingers at the end of the slider is good enough for most. You also shold rotate the wheel and check as you go to find the tightest spot and set for that.

[07wr250]

Yup, chain slider and rollers are the cause (as well as a worn out chain) in most cases. Also running extreme sprocket combos (12/60-Yikes!!!) will do it too.

Chain should be correctly tensioned. To see what is truly correct, you need to move the suspension to the extremes of travel and ensure the chain is not tight and has some up and down left. But nearly no one does this. Three fingers at the end of the slider is good enough for most. You also shold rotate the wheel and check as you go to find the tightest spot and set for that.

Both chains are between 1.9-2.4 inches of slack, as the manual says. One bike has a 51 tooth in the rear, the other is stock. I'll look into replacing the sliders and rollers. Thanks guys ?

[Mark6299]

If you want to go through chains and sprockets fast, tighten the chain up. I you don't then leave it alone. I am just kidding of course. All my bikes do the same thing as far as the noise issue goes. I just don’t let it bother me. I had them tighter on a few of my bikes before and they were quieter but they didn't last very long at all. The chain NEEDS to be a certain amount loose when the suspension is bottomed out at the point where the front sprocket, the swing arm pivot and the rear sprocket are exactly in line with each other. If the chain is too tight, it will be under a huge amount of tension and WILL make it's self loose to the point that it's happy. When that happens, the pitch of the chain is changed. In other words, the distance between link pins is increased. What happens next is the chain, with a different pitch, tries to engage the sprockets, which still have the original pitch. It doesn’t take long, at that point, for the chain to convince the sprockets to share the same pitch. When they do, it is about the time that you need to PITCH the chain and sprockets into the trash. Pun intended. So now you could keep buying chains and sprockets very often, or set it up properly, as you have done, and enjoy worry free chain and sprocket life for a very long time. I learned the hard way. I am now on the same set for over a year, without any stretch or wear at all, but, I do hear the slap. Oh well. I will look into the chain guide as mentioned by a poster. I thought mine were in good shape but it's worth a look, especially when someone stated it made a difference. I hope I didn’t bore you too much or didn’t insult your intelligence. I was just trying to help. Good luck and keep us posted with your results.

[YZEtc]

I agree with the above:

Run enough slack to prevent the chain from running out of free play when the front sprocket shaft, swingarm pivot shaft, and rear axle are aligned (which will be the case a whole lot while riding the bike, so you may as well get it right before you ride it).

The reason why the slapping noise it loud is because the chain slider is not screwed down tightly against the swingarm, but instead, the mounting bolts have spacer collars built into them to prevent the slider from being tightly screwed in place.

So, it is free to wiggle around a bit around it's mounting holes, which allows the area between the mounting holes to raise up away from the swingarm a little bit.

When the chain gets tugged on by the front sprocket, it slaps the raised part of the chain slider down against the swingarm.

You can reduce this by removing the chain slider (and buy a new one if it's worn out or about to be), clean the inside of the slider and the swingarm, apply silicone sealant to the slider on the area between the two upper mounting bolt holes, and put the slider back on.

This helps to cushion the slap of slider against the swingarm.

[barns19]

drop it down a gear and see if that helps. mine rattles at low low rpms

[53fireman]

+1 on the silicone under the chain slider

[jcbikes]

What YZetc said about the silicon but I use instead, a cut to length between the two upper bolts, Mt. Bike inner tube and it helps a lot.