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Discussion Starter #1
I picked up a 2520 that wasn't running for about $100 and torn the engine down to find that the crankshaft appears to be stuck to the crankcase on the flywheel side of the engine. I can't tell by the diagrams on the Kawasaki website, but is there a bearing in that opening that could have gone bad and locked down onto the shaft causing it not to release? Or possibly, there is just something stupid I'm overlooking here. Never seen anything like this in an engine before. All the parts diagram shows is a sleeve and a rubber collar (I have removed the collar) so I don't know what else could cause it to not release. The rest of the motor is in good shape, so if I'm unable to resolve this and have to spend the $1500 for a new motor, I will have a bunch of good engine components to get rid of if anyone is in need. Thanks in advance for any advice anyone might have.

CH
 

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It has been a while since I had one of these apart, but the case splits from one end. The biggest chunk of the case that includes the crankcase and cylinder boss has a main bearing and a seal, and the smallest side of the case has a built-in waste of time bearing that is not normally replaceable and an oil seal to the outside of that.

Nearly always the bearing on that small side or plate is the one that seizes to the crankshaft. Your best bet is to use a press and press out the crankshaft. Most machine shops that work on engines know exactly what to do and how to support the case side to keep it from cracking. Once the crank is out, they will machine the case and make a main bearing insert that fits in that side of the case. They will also resurface the crankshaft on that bearing. They also know how to index the oil holes.

If it is the other end that is frozen, they will use blocks of wood and press out the crank and then the bearing will usually come out with a tap of a hardwood dowel and a mallet.

The most common cause of bearing(s) seize-up is lack of oil or running dirty oil. When you pulled the cylinder assembly you will have seen evidence of scoring or bluing on the piston and cylinder if it has been run low on oil or with dirty oil.

Just do not try to pull the replaceable bearing without first removing the cylinder and splitting the case. If you attempt to replace the bearing with the engine case still assembled you will ruin the crankshaft by springing it out of true, and may as well just buy a fully rebuilt or new engine if that has been tried.

Sometimes it is necessary to use a great deal of top quality penetrating oil to get the cylinder assembly from the piston, but it will come off and also must be done before attempting to split the case and pull the crank.
 

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Discussion Starter #3
Thanks a lot for the information. The crank is stuck to the larger side of the case so I'll take it to the shop and see if they can press it out and see if its salvageable. When I first cracked into it, it didn't seem like nearly enough oil drained out, so I initially assumed that to be the problem and figured a piston had locked up in their from not getting enough oil. However, they came out pretty easily and didn't show any damage, really, to speak of, so I'm hoping that its just the bearing that has suffered from this guy's stupid moment and the crank and case can still be salvaged. Thanks again!
 

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If the case cannot be salvaged replacement parts are available from guys like Kawasaki Parts House for much less than OEM prices.

There are a couple things you should do if it was run without enough oil. Replace the original piston and rings, the old one will have the temper out of the rings and will now puke oil like a 2 stroke, and even with knurling the skirt the old piston will start knocking in just a few hours of use as the aluminum gets softened by the excessive heat from no oil. Mic your cylinder bore and make sure there is no taper from top to bottom and that there is no ridge on the top. If there is anything in top to bottom bore taper of over .002 of an inch, rebore it. Then do not use Kawasaki's crummy piston, rings, and wrist pin, but go to Wiseco and get a package from them. It will less expensive and ten times the quality - get it in the oversize you bore to if a rebore is necessary.

The next item is to replace both crank seals with new ones from Kaw, get their current upgraded version they are much better. Also, replace the oil pump with a new oil pump. five minutes of low or very dirty oil on the older pumps and they wear so badly that they will not hold adequate pressure. The new Kaw pump is an upgraded unit that corrects oiling problems from earlier versions.
 
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