426 Engine knock

I have a 2000 426 that has a knock in it that I can't seem to find. When it is at idle or chugging it sounds a little like a small marble bouncing around in the lower front of the motor. I am thinking that it might have something to do with the balancer shaft or water pump but both appear to be fine. Is the water pump shaft supposed to have any play in the balancer shaft? I can wiggle the water pump a little back and forth. I've gone through the motor and everything else checks out to be in clearances.

Any help or ideas would be greatly appreciated!

my 400 was making noise right before it blew up..I found that the bearings on the balance shaft seemed to be bad, along with the big-end bearing on the con-rod

have you checked your connecting rod for play?

On my 01 426, it was the primary drive gear rattling around on the crank. The nut had backed off about a quarter of a turn. If you haven't checked that, it's easy to see with the clutch cover off. See if the clutch basket moves when you hold the crank with a socket on the flywheel nut.

My 02 has always sounded like that when I lug it up a hill. Does it in all gears, I guess I just thought it was pretty normal. I have not had any problems so far.


I've checked the rod and crank and they are still well within limits.

I haven't checked that but that could be very possible. The noise just seems like a thinner metal object rattling around in there. All specs are ok but if anything the noise really seems to be coming from the bottom left side of the motor, but who knows maybe it's just resonating on that side for some reason. I think I'll re-check teh balancer bearing too. Th thing still pulls hard and there are no performance issues, but I really don't want to see pieces blow out of the case one of these days.

I FOUND IT :thumbsup::applause::applause:

The problem was a bad keyway that is on the gear that turns the counterbalance shaft. The key had slight wear marks on both sides which allowed the sprocket on to move back and forth quite a bit. The counter balance shaft magnified the sound of that sprocket through the lower front part of the motor. I chaged the key and the bike purrs like a kitten again.

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