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NEW TOP END 07 KX250F

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Might be the same as an Rmz 250.Im not sure what year they were the same but 07 rings a bell.I think I'd start out fresh with a bb kit.

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I am looking to freshen up the top end of my 07 kx250f, can i buy an OEM piston and cylinder from kawasaki and put it together with new valves etc. OR does the cylinder have to be machined to fit the piston?

appreciate any comments...

If u have an oem piston in there now. It should fit again. But it's important to mic. Your cylinder. To see if it's out of round.

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The bike is completely stock, so if i were to go to rocky mountain MC and buy a new oem piston with cylinder it would work? I'm switching out the piston and figured id just buy a new cylinder instead of machining the one i have now.

 

^Jdrost


no problem Bforte

Edited by KXRIDER159

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A new OEM piston/cyl will work just fine.Reason I suggested a big bore kit is you'd have a bigger piston/cyl bore=more power verse stock power.The only thing is you won't know what shape your crank is without inspecting it.Out of true,sloppy and or shot bearings.Do you know how many hours is on bike?Flying over the handle bars isn't any fun when Conrad snaps/locks motor up.

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If you are going to do the topend, send the head off to have seats cut and the head cleaned up and the valves lapped if they are in good shape. Your local shop is going to be able to hone your old cylinder which will save you money to have your head redone. Having your head cleaned up is probably one of the best things to do to your 4 stroke when you are rebuilding it, it gives it that fresh snappy feel again. Good luck

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If you are going to do the topend, send the head off to have seats cut and the head cleaned up and the valves lapped if they are in good shape. Your local shop is going to be able to hone your old cylinder which will save you money to have your head redone. Having your head cleaned up is probably one of the best things to do to your 4 stroke when you are rebuilding it, it gives it that fresh snappy feel again. Good luck

 

You cant lap valves as it will destroy the coating, you can only have the seats cut to fit the new valves.

 

You can not hone the old cylinder as they are nicasil coated so can only be cleaned up, if the nicasil is still good and the cylinder is still in spec then you can just fit a new piston   

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You cant lap valves as it will destroy the coating, you can only have the seats cut to fit the new valves.

You can not hone the old cylinder as they are nicasil coated so can only be cleaned up, if the nicasil is still good and the cylinder is still in spec then you can just fit a new piston

U can run a deglazer real fast

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You are right about lapping the valves, sorry been watching a lot of videos on diesel rebuilds and thats a common thing to do to those. However, your cylinder can be cleaned up and yes you do 'hone' it because you use hone to clean it up and give it new cross hatch. They do have over sized pistons so order accordingly, however they are usually never needed because nikasil is so strong. Good luck on your rebuild. BTW FYI Kibblewhite valves are very good and are priced in the right range for most people.

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