Possibly a broken ring?

My brother rides an '01 YZ426 and was racing a hare scramble today and said that his bike popped and then the rear wheel locked up and it died. The motor will still turn over but I do not want to attempt to start it. When I do turn it over with the kickstarter, I can kind of hear a metal-to-metal noise so I'm thinking that a ring broke?? Any other thoughts? :thumbsup:

Pull the head off and look for a broken piston skirt, dropped valve or broken rod (pop! sound..)sorry for your loss.........

I guess me and my bro will have to take it apart sometime this week. :thumbsup:

Take a good look at the lower rod bearing. I had one go out on the same year bike, but mine just locked up solid. :thumbsup: Let us know what you find.

We're probably going to be taking everything apart this afternoon (at least the top end). Either myself or my brother will be sure to take pictures and post back. I really think it's a broken ring though...just a hunch. :thumbsup:

lower connecting rod bearing siezed... :thumbsup:

looks like time for a new crank and a new top end while were in there.

also, can you lap the valves on these heads? figured I might as well while it's apart

No, you cannot lap titanium valves, it will ruin them. You can cut the ti valves and there seats but it requires specialized equipment and from what I hear not many shops will do it.

Thanks for the information. :devil:

I priced parts tonight and I think it's going to be about ~$500 for a new crank, top end (including timing chain, piston, rings, gaskets, wrist pin, etc.) and a few other odds and ends that he needed. Not bad..coulda been worse, for sure! :thumbsup:

That's about what I spent in parts to do mine last spring. You might as well change out the Crank end bearings while your in there.

Bonzai :thumbsup:

Well, it looks as though the crank end bearings (#7 on the "Camshaft Piston" fiche) are on backorder. Do you think it would be just as good to go to a bearing shop and get a couple of them made?

So if no one says any different, I guess we are going to take the old crank end bearings out and get some new ones made at the local bearing shop... :thumbsup:

Big Negative Ghost Rider

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