2009 YZ250F Cracked Case

Hey guys, i'm in process of a top end rebuild on my 2009 250f yam, and I found something along the way.

The clutch side crank case has a decent size crack in it, running across a couple spots where the bearings are seated.

Anyways, a buddy of mine told me I wasn't able to purchase only one half of the case, for it wouldn't fit exactly right with my existing side..

Since I have a lack of experience in splitting/replacing/anything to do with cases.. I figured I would come here and find out, since I didn't just want to venture off on only one opinion.

So, am I absolutely required to buy BOTH sides of the case if only one side is faulty?


Are you sure it is cracked and not just casting flash? Post a picture.

Yamaha cases are sold in pairs/sets.



Heres some.

Edited by Rox

That is a big crack, both sides with need to be replaced as a pair. Yamaha line bores the cases while they are bolted together, so if you were to mix and match cases the holes wont line up perfectly.

Yeah, that Def. looks like a crack. Did you have something catastrophic happen or did you just get it used?

New cases are called for.

Purchased the bike used, and yes something catastrophic happened.

Piston somehow turned vertical in the cylinder, shoving it into the valves and caving in the cooling jackets in the cylinder.

Needless to say, I have a few dollars wrapped up in it so far, I have all of the parts necessary to rebuild but I figured I would do a reassuring check of all components before reassembly..

And that is what I found. =\

So it looks like a new set of cases then for sure huh?


Yup, new cases. The split will increase and the costs to get it welded really is not worth it compared to the cost of cases.

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