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YZ250F overbore???

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05 yz250f

Piston is pretty messed up bottom skirts are broken. It scratched the bore pretty good.

I will rip apart the entire engine to make sure the big pieces of aluminum didn't damage anything.

I was thinking about getting it bored and putting in a bigger piston.

if it did would I get it re-plated with nikasil or put in a sleeve? Do not want to buy a bigbore kit because of the cost.

So have you guys overbored your yz250f? tips? suggestions?

Thanks in advance

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Cylinders for your bike are a pretty reasonable price. You should be abe to pick up a new big-bore cylinder for about $250. A new stock bore cylinder will set you back around $200. You will easily spend $200-$250 to bore and replate your stock cylinder. Installing an iron sleeve won't save you any cash either and you will have the added hassle of trying to find piston rings suitable for use in an iron cylinder (you CAN NOT use piston rings for a plated cylinder in a iron liner cylinder).

Check the condition of the rod bearing and main bearings closely before putting the crank back in service.

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Thank you for the response I did not know about the rings being incompatible.

Can you recommend a brand?

All I need is a bore and piston? obviously gaskets...Will everything else be compatible? The kits I have seen are around $800.??

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Check your local dealer. They should be able to get you a Cylinder Works big-bore kit for about $550. You can also check ebay or Rockymountainatvmc.com

The Athens kits are a little more spendy, the $700 range like you've seen, but they are a little more displacement (290cc vs. 269cc). Most kits available are quality parts. I really haven't heard of anything to avoid.

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Luke's racing has really great prices on big bore kits and stock sizes as well. I agree with grim. You can find a nice big bore kit (290) for around $500 on ebay.

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I got my Cylinder Works 269 kit for $400 and I just did a google search and quickly found several for the same price.

So far, I have put 150hrs on my BB and it has performed flawlessly. I highly recommend the product.:bonk:

Edited by indy rider

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