WR426 Engine Rattle?

This is a guess-

There is a loud knock or rattle at low speeds that is of no concern. The chain slaps on the top of the chain guide by the swingarm pivot and can be very loud at times. This is usually at light throttle positions when the chain goes slack and then snaps back tight.

A softer guide pad will be less loud but will wear out much faster. After a while you just quit noticing it.

Hope thats all it is.


[This message has been edited by James Dean (edited 02-03-2001).]

As I said in an earlier post the bike is awesome! One thing though. What is that terible engine rattle at low RPM's? My buddy and I both bought one last week. We both have the rattle in the engine! Mine is twice as bad as his. We tried each others bikes and verified it wasn't the riding styles, but we both have the noise. Another friend just bought a WR426. He had a 00 WR400 prior to this (and yes HE is rich!), and he says the 400 didn't have that rattle. His new 426 does. I haven't ridden his, nor him mine, but I am concerned that this is or will be a problem! And why is mine so much worse? The dealer says he doesn't have any clue about the noise, but since the bikes only have a 30 day warentee, I need relief fast.



My friend and I also purchased two new 2001 WR's. with the same slap/knock from the motor. My dealer indicated all of the yz426's also did this.. looks like a feature

Originally posted by AhamayWR426:

My friend and I also purchased two new 2001 WR's. with the same slap/knock from the motor. My dealer indicated all of the yz426's also did this.. looks like a feature

Oh no, must of been made by Microsoft! Another undocumented feature!

i'VE BEEN PULLING MY HAIR OUT OVER THIS VERY SAME THING FOR THE PAST FOUR MONTHS ON MY 00 400. I've described this sound as almost sounding like a 2-stroke knocking and pinging, but it seems to have gotten worse as the chain stretched. Do others have similar sounds from 400's?


When you hear it, hit the throttle, if it goes away your ok. Mine does the same thing when she gets bogged down. The only thing you dont want to do is bog it to the point it sounds like it is missing. When you hear it down shift or nail the throttle. It should go away. If you find the speed you ride is almost between gears,making you bog down a bit, a gearing change my help.

Keep the revs up a little.

I have had a similar rattle on my '00 WR400 - check the nearside frame down tube - the noise on mine was the chain rubbing on the tube - it still does and no matter what I do i cant stop it ( See earler posting )



Is this your first bike?

When my 01wr did the chain slap rattle it reminded me of my old Husaberg, Ktm, Husky...

Lugging it definetly makes more noise but it didn't come from the engine.

Forgive my condecending note, I thought all bikes did this when you are tired, hanging on, just trying to get up that next hill without grabbing a gear.

BTW, guys behind me said hey man your bikes rattling...

Ty Davis sells different chain buffer plastic, maybe this is why...

Not sure if your problem is the same as mine, but I took delivery of an '01 WR426 in December. On it's maiden ride I nopticed what sounded like detonation knocking when I got on it a little hard at speed. I backed off, afraid of breaking my new machine, or at least doing something that would come back to haunt me in later (bike) life. The manual says it eats 95 or better octane, and 92 is the best they sell around here as premium at the pump. This seems to be a state by state setting, what octane is legally called premium. Then I found a place that sells 100 octane Sunoco racing gas at $2.30 a gallon. Hey, it's only money, right? Anyway, that did the trick on the detonation, knocking sound is gone. Still only have 28 miles on it, waiting for the snow to melt...


Bill in Colo: '01 WR426F, '98 KLX300R, '01 TTR125L, '78 DR370, '74 DT360A. (My wife is a saint!)

My 01 WR426 does this also. I tried higher octane fuel and then road a buddies' 01 YZ 426 and it did it also.The sound is just chain slap.

I have a 2000 and hear a light constant nack nack nacking when I hit 60 mph and over, with a 15/50 ratio....??? anybody?


[This message has been edited by joecallan (edited 02-25-2001).]

The sound is definetly coming from the engine. My 01'WR426 makes the same sound at low rev's. As soon as I give it a blast of throttle I dont hear it. It sounds like a slight knocking, so Im going to try higher octane gas and see if that helps.

I have a new wr250f and I have noticed the same thing at higher speeds, in 4th or 5th gear. it had me a little worried, but I have a feeling its chain slap. haven't ridden the bike enough yet figure it out for sure though. it doesn't happen when I rev the motor at idle.

Anyway, I only notice it when the exhuast is corked; I just uncorked the bike and now I can't hear it or anything else.....


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