New crankcase?

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You will likely need a wiring harness though as the PO cut it up a good bit to add various electronics - tboost, fan switch, etc...
 
Yea, you can see where the crank was binding into the block on the thrust surfaces. Case is toast (as will be the crank).
 
The crank itself looks pretty beat up to me, but I'm not seeing what you're talking about on the thrust surfaces. I'm wondering if I'm looking at the wrong spot, how can you tell?
 
I think Sean is referring to this post where the crank main w/the reliefs in the case for oil supply has a worn semi-circle around the case side. Look to the left of the right piston on the side of the block for the semi-circular wear area.
 

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Oh damn, I totally see that, now that you point it out. It's dug in pretty deep too. What causes the crank to do this?
 
Binding of the crankshaft when the rod bearings start to fail. Some manufacturers make that a bearing surface that can be replaced. Yamaha simply machines it into the aluminum of the block with no replaceable bearing. We have fixed that area before but the cost to do so is not worth the expense unless the block has a lot of other work (like big bore or chain drive) to make it worth the cost of repair.

Is your other block good? There are two surfaces machined like that (which I can't see the other one in your picture).
 
Sean, when you have repaired the thrust surface, do you add material and then machine it down? When the surface is a replaceable area, is it a screwed-on semicircle for each case half? is it a single thickness replacement, and is replaced once it wears, or like bearing shells, does it have to be measured and different size inserts are used? Apart from rod knock, or inspection after disassembly, what are symptoms that the thrust surface is wearing? Can free play be determined by exposing each end of the crankshaft and seeking excess lateral movement?
 
Link doesn't work. Balancer shafts are cheap and you may have a hard time selling it (if it's good). I was talking about the second complete engine cases you said you bought. Was just curious if that set was damage free in that area. All too many times when I see bare cases up for sale there is a problem with the case (either crash damage or had a crank failure which damaged the same area as yours).
 
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