'01 426 rattling underneath

At idle and pretty much throughout the RPM range, I have a rattle or "chuchuchuchuchu' (If I had to spell a sound). I do not live near railroad tracks nor have Thomas the Tank Engine soundtrack playing. Are we talking rod bearing/crank bearing/time for a new crank assy? I know the 426 is a mechanical sounding motor and the skid plates reflect engine sounds, but I believe it's been growing noticeably louder

regular oil changes and yes, fine metal particles in the filter but never excessive amounts IMO. To do a crank replacement, what else should I do while it's split? cam chain is still tighter than a nun and the marks are spot on.

Have you had the case covers off? On a 2000 426, the counterbalancer drive gear is mated to the crankshaft with a key instead of splines. That key gets bent and the drive gear clacks around - probably not your issue if you have a 2001.

On the other side of the motor, I had a pressed-on interference fit oversized flywheel weight come loose once, and it made a hell of a clatter.

I also once had a clutch spring bolt work loose, and it contacted the clutch cover when the clutch was disengaged. That was a fairly awful clatter too.

Are the valve clearances in spec? That can make some noise.

I know from experience that a rod bearing doesn't make a lot of noise before it lets go - the bike loses power gradually for a while, and then it just locks up dead one day. That's not so much fun.

I hope you find the source of your noise, and I hope it's one of the easier, cheaper things to fix.

The covers are coming off this week. I figured I would be finding more shavings in the oil if it was bearings too. Working too damn much to spend time in the garage. Good thing about working too much to play, is that i'm not spending money on any of the toys.

I'm not opposed to a tear down and rebuild actually. I've never had it all apart before. And as far as a rod bearing not making noise before it goes, i'm sure it varies from situation to situation. For example, but not specifically, my Tacoma makes a lot of valve noise, but they are all in spec.

Probably a bit obvious, but the nut on my front sprocket managed to get loose once and that would rattle on the overrun in particular, or when idling.

Like I say, probably a bit obvious, but take a quick look anyway!

On a YZF, a loose front sprocket will cause a huge oil leak. The transmission is pressure fed.

On a YZF, a loose front sprocket will cause a huge oil leak. The transmission is pressure fed.

Hmmm. Didn't on mine :)

I does have to loosen up about 3/4 turn on the nut in order to leak, but not much more than that. Possibly the lock washer kept it from going that far.

The front sprocket is tight. Do I NEED to buy a case splitter? Or does patience and a little time work too?

You can split the case by hand, and take it to a shop to have the crank pulled. Hopefully you'll find the problem before it gets to that.

I does have to loosen up about 3/4 turn on the nut in order to leak, but not much more than that. Possibly the lock washer kept it from going that far.

Yeah, I think that was the case. The lock washer had let the nut slip a bit, but not that much. It didn't need much looseness to rattle, though!

I pulled the covers today, Stator/flywheel side, everything was clean and tight. Although there was slight in and out movement of the assy, how much is acceptable? The clutch side is a little different. Definite wear and wonder where a piece of the lock washer went. Possibly ground up and that's what I was seeing in the filter after the last change, this filter was clean. It looks like it was filed down once before. Slight in and out movement of the splined shaft.

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So should I replace it all? Plates and rings look good yet. The aluminum parts are really the only thing worn, and the broken lock washer tab. Could all this be the sourse of my noise?

I'm also guessing the blackening is from oil over the years.

I put a new clutch in mine and noticed my hub was the same way. I also had the lock washer with a tang missing. I got another hub off of ebay and ordered another washer when I did the new clutch and now all is good. I would recommend replacing it. Mine had alot of play where the splined shaft goes through. The inner part of the hub is a pressed in piece of steel with the splined teeth made into it. Mine was so loose the whole clutch hub and pressure plate assembly had alot of play. I got a hub and pressure plate off of ebay for $40 shipped.

I have found a couple complete clutches on ebay. But I am waiting for more pics of the wear surfaces before I buy. I cannot justify spending the money for a Barrnett, Hinson, MSR or even a Wiseco for how often I get to ride anymore. There is alot of play in the clutch on the splines as well. There is also about 1/8" or so of play between the primary and the basket itself, the springs seem to have compressed/shortened.

As far as in/out movement of the splined shaft and flywheel shaft, how much is accceptable? There is a little, but everything spins smooth with no vertical or side to side movement.

So maybe I titled this thread wrong. Either way, can someone chime in on the in and out play of the splined shaft?

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