02 yz426 seized, HELP

was just out rippin this afternoon and my 426 seized!!!! I thought before i started ripping into it, I'd ask everyone for there input on how theres seized and where, figured thered be a couple out there who had theres seize up and can tell me where to start, bike had oil in it btw.

I have the same problem with my 03 yz450f, I also have oil in mine. Anything I should do before I open it up? Any help would be great. Thanks

was just out rippin this afternoon and my 426 seized!!!! I thought before i started ripping into it, I'd ask everyone for there input on how theres seized and where, figured thered be a couple out there who had theres seize up and can tell me where to start, bike had oil in it btw.

Its not real common to hear about them seizing, but more and more older bikes seem to be locking the big end bearing up on the crank. Unfortunately 4 strokes typically don't seize the top end like a smoker does. Usually its the crank.

You need to start by pulling the motor out of the bike and start peeling parts off of it.

Yep, it's usually the rod.

Just happened on our '04 450. Lower rod bearing seized.

Parts list was as follows:

Crank Assembly

Crank Bearings

Crank Seals

Cylinder (When the rod siezed, it forced the piston into the cylinder wall)

Piston & Rings

Cam Chain

Cam Chain Guide

Gaskets

Parts total (no labor) was just a shade over $700 from Service Honda with shipping - and yes, they sell OEM Yamaha parts.

how deos this rod seize? not riding for long time??????????????

how deos this rod seize? not riding for long time??????????????

The bearing just gives out from use. Nothing lasts forever.

The bearing just gives out from use. Nothing lasts forever.

Even a Yamaha?

I haven't heard about too many YZ failures, though I know they're out there. I wonder how hard the ones that are failing have been pushed and how well they were maintained?

Even a Yamaha? ... I wonder how hard the ones that are failing have been pushed and how well they were maintained?
The newest 426 is now fully 6 years old, and most of them have never been apart in any major way for any reason. I don't think I've heard of this on anything other than a high hour bike, and not at all since they upgraded the rod bearing last in '04.
Even a Yamaha?

I haven't heard about too many YZ failures, though I know they're out there. I wonder how hard the ones that are failing have been pushed and how well they were maintained?

I haven't had one fail. But, I have replaced my crank just as good preventative maintenance. My bike gets rode almost every weekend and sometimes we travel 4-5 hours to ride, so failure isn't an option.

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