Chain slap

My WR 450 seems to have an awful lot of chain slap and it doesn't seem to matter how I have the chain adjusted, or how sloppy lubed it is. One of the guys I ride with (on a KTM) says he can always tell when a Yamaha 4 Stroke is coming up behind him because he can hear the chain slapping before he sees the bike. Is this normal? or do I need a new chain and sprockets? Of course its been 2 months since I have ridden and that sound would be real welcome about now, actually between the sound of the GYT-R exhaust and the chain slap, I can't think of a prettier sound. :)


I don't know how normal it is, but I know mine does it too. I have checked my chain and it has right at 2 inches of travel and the manuel says 1.5-2 inches of travel. So I am hesitant to tighten it too much. I would like to know if it is normal too though.

Mine does the same thing too!

Seems it is hitting the bottom part of the guide/bushing on the swingarm . . . regardless of chain tension.

just went over 2000 miles this last weekend. Mine will do the same thing but usually just tightening it to spec and lubing it will take away the slap.

My 01WR426 used to slap a lot to. I cut and glued some old bicycle tubes under the chain slider then tightened the chain to about 1 3/4" of slack with the rear tire off the ground. No more and no less then 1 1/2" of slack. Works for me no more chain noise.

If it does start to make some noise it's not bad and I know it's time to check the slack.

This seems to be an on going problem with Yamaha 4 strokes since the YZF was introduced. I glued some thin rubber under the chain slider as shown in motoman393's tech article .

My swingarm was starting to show wear from the slider being pounded into it by the chain. Read the article. If left alone it looks like you could end up with a cracked swingarm.

:) Lowedog

I like to thank u guys I could not figure out what the hell that noise was on my 2002 wr 426 I kept hearing it riding at slow speed now I can fix it thanks again. :):D 2002 wr 426 w/b e-series lid off airbox put a switch on my grey wire 2 different ignition timings 170mj

Jim. You must have an aftermarket chain, probably Regina ?Check the inside of the aluminum subframe, bet it's all scratch up from the wider, beefier chain. My WR450 does it too, only at a steady throttle at speed. Get on the throttle, the chain tenses and the clatter goes away. My advice ? Stay on wide open throttle all the time . Wish the aftermarket made a roller chain guide for the top of the swing arm......

I made a slider out of white teflon ,new one is 90 dollars Canadian :). You should hear the noise it makes. I was thinking of glueing some rubber under it. Not sure if it will help.

Don't over tighten the chain to get rid the noise :D. You may ruin the counter shaft seal.

I've also noticed my WR sounds like the bottom end is rattling apart at low RPM, lugging it. Is this the sound from chain slap? It appears to be more noticeable on the left side.

PBWR450. I hear that too, happened on my 98WR400, 02WR426 and now, although less noticable, on the 03WR450. I have no idea what that sound is other than chain slap, cam slap or detonation ? I'm running a 50/50 mix of 108 race and 91 pump as always, so detonation is out. Must be the chain or the cams ?

I initially thought it was detonation too because I have'nt made any jetting mods yet, running 91-93 octane pump gas. I heard a YZF 450 at a track once from the sideline that appeared to have the same sound when coming out of a corner and setting up for a jump down low. Thats the only other WR/YZF I have heard run.

I've also noticed my WR sounds like the bottom end is rattling apart at low RPM, lugging it. Is this the sound from chain slap?


your chain is beating your chain slider into the swingarm, which in turn will wear the swingarm. we've seen some cases with extreme wear right at the swingarm weld line, so much so that a crack is starting.

this is what your slider is doing to your swingarm as a result of the chain slap and the gap under the slider:


basically, sand and dirt get trapped under the slider and then the chain pounds the slider (and dirt) into the swingarm. YOU CAN NOT FIX THIS BY INCREASING CHAIN TENSION -- you will just accelerate wear on your sprockets and transmission if you increase the tension.

read the 250F FAQ link which i posted above, ok i'll give it to you again -- -- and glue some kind of buffer material under the slider (i.e. USE SOLUTION #2 in the FAQ link, see pics 4, 5, and 6). the chain slider fix takes all of 10 minutes, only requires taking 2 screws out, and once completed will dramatically quiet your drivetrain. no more chain slap noise, no more wear on your swingarm. two birds, one stone, all done in 10 minutes.

jim aka the wrooster

'01 wr250f

Thanks for the help. :)

do the inner tube/rubber trick. it almost feels like the bike runs better. i know that doesn't sound right, but the chain slap is so distracting.

It does sound like all of the people above are describing chain slap noise, it does sound like it's coming from the motor's bottom end while you are riding.

Trust in us O followers of the TT... Take the screw loose on the top half of your chain slider, lift the slider up, clean under there real good, then just stick something soft to the swingarm under the slider. I used 3M two sided tape, it's like 1/16" thick or so, and it did the trick. MUCH quieter, and SO EASY it's ridiculous.


Jim, I try not to let my chain have too much slack in it, it keeps the wear to a low on the slider. As far as any sound it makes, I don't think the WR/YZ bike makes any more or less noise than other bikes.


As far as any sound it makes, I don't think the WR/YZ bike makes any more or less noise than other bikes.


dan, that's 'cause you always have your bike rev'd up so high, you can't hear it... :):D :D

the rest of us are going slower and we can hear every bolt rattle.


jim aka the wrooster

'01 wr250f

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