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2003 yz250

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Hey what's up guys I picked up a mint 03 yz 250 that had a really bad knock today for dirt cheep. Bike was sold to the person for 2k last week and they seemed to blow it up by not mixing the oil in the gas lol. Any how I pulled the top end and found the rod main bearing has up and down play like 3/8 of an inch :(. . Any how it was not seized but I'm sure there needle bearings ground up in crank case . I'm pretty sure the metal won't go into gear box. I just ordered a hot rods bottom end kit for it. The cyl looks good still but who knows . Still has plating.

Any tips you guys can give me? ImageUploadedByThumper Talk1408487509.176572.jpg

Edited by Jd267

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The cyl looks good but I'm going to have it looked at by machine shop to check for out of round etc. paid $450 I did not do a compression check but it had a lot of compression but if they ran it with no premix the cyl could have got cooked also. Piston shown a burn mark on exhaust side but no scoring etc.

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There is no chips in plating either . Bottom end bearing have no play either but changing them any way. Bike looks like it was cared for and not beat on till recently

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While you have the motor out of it, pull the swing arm and linkage, clean and re-grease (but most likely replace) all the bearings. That's the most over looked area on any bike it seems.

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ImageUploadedByThumper Talk1408500438.636521.jpgImageUploadedByThumper Talk1408500449.187302.jpg

Looks like there are no needle bearings left !

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While the cases are split for the bottom end double check everything. New crank bearings and seals to go with the new hotrods and I would also check all linkage and swingarm bushes and bearings and replace if necessary as previously mentioned.

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Tore down the bike today everything looks good . Bearings in trans are a little ruff I tried cleaning them but they don't roll smooth so I ordered new ones. Do any of you guys know where I can get a free service manual? 03 yz250

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So this bike I think is still on the factory top end bore. It's a B cyl and std piston. The plating is not chipped or anything . Should I have it redone or have a machine shop check it with bore gage to spec? I'll post up some pics of it.

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Check out the burnt bearings and brown in the crank case lol. Kit really smoked this top and bottom end . Must have ran it with no pre mix or not enough . The clutch has NO marks on it and the wrest of the engine looks to be in really really good condition . Must have been a low hour bike and well taken care of .

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I would advise you have the bore measured for roundness and size while its all apart. If it checks out and there is still hone hatching you will be fine

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I don't see any cross hatch in the Cyl. Looks tired to me I'm prob just going to send it out for a exchange.

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Have any of you guys worked with Millennium Technologies ? Seems like a good price after I send them mine.

What other company's have you guys used?

I send mine to pro seal or power seal I forget which name it is. Oops lol but they do fantastic work for a better price. They can repair and replate cylinders. My local dealership uses them for every rebuild they do. Highly recommended from me.

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Power seal. Just looked $185! That's cheep! I'll give them a call

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They fixed and replated my Yz cyl. It was in pretty bad shape too and it is perfect. Just follow their process and it will work out great for you. And it's cheaper to send your own new piston btw.

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