2010 kx250f Full Motor Rebuild!

Aright,  so I'm doing a Full rebuild on my 2010 kx250f. Top, bottom, valves, the whole works. I have 100 hours on the bike with the stock bottom end. I have replaced the piston twice in that time. I would like to get some input on what's good and what I should stay away from. I am also looking for some extra kick like cams and high compression piston. Any other little mods worth doing instead of that?  All input is appreciated!!


I'm going with the Hot Rods bottom end kit but not really sure what I should be going with in the top end...


- Better valves to be going with? OEM titanium, Wiseco, Kibblewhite, steel?

- Vertex VS Wiseco

- High Compression VS standard

- Thoughts on Hot Cams? stage 1, stage 2?


What are all you guys running in your 09, 10, 12, and 13, kxf's?? Thanks!!



2010 kx250f.jpg

If you do valves, you have two sensible options. Take the less performance oriented approach (and it sounds like you want more if your talking cams ect) and put stainless valves in and proper springs. Or do the Right thing and put copper valve seats in with new TI valves. You can shop around and get OEM TI valves for about 55-60 bucks a piece so it is quite a bit cheaper than 100 a piece from del west.

Buy a moose piston, its a rebranded Carillo, which is one of the best in the game.

If you're not absolutely dead set on the hot rods kit, and are willing to spend a bit more money, get a moose rod (again a rebranded carillo) and put it on your stock crank. Otherwise the hot rods is fine, just DO NOT buy a wiseco bottom end. They subbed their cranks out to china and are no good.

High comp piston will give the bike more low end and depending how high you may need race fuel to bring the octane up so it wont detonate.

I've got a set of hot cams for that bike that have minimal time on them that i'll sell dirt cheap. PM me if interested.

Thanks! Appreciate the response. I would go with the Carrillo piston and rod but I don't have a way of getting through the support that I have...just wiseco and vertex.

Weisco is a good piston but I heard their cranks are junk.

use oem valves , very good stuff.

get the valve seats conditioned ( regrind )

new springs, retainers and collets.

Spend the money and get a crank... A discount price on a wiseco crank still ends you with a blown crank and possibly waisted cases and top end 5 hours down the road. Not something id skimp on.

If your spending the money to stick with TI valves, do the copper seats. Having the junk stock ones re cut is like lighting 300$ in valves on fire and watching it burn.

Never heard that before. ???

Never heard that before. ???


The TI valves are a way softer material than the Hardened steel alloy valve seats that are in the head frmo the factory. Not only will the heat be dissipated way better through the copper seats, you wont be beating the valves on a much harder material.  This is why everybody thinks the "fix" is stainless valves, because then the material properties are closer to the same hardness. 

Edited by dmm698

I like SS valves because they are cheaper and won't disintegrate in a blink as Ti valves will if their coating wears off.  And because we aren't exactly racing for money.  That said, it does make sense to pair Ti valves with copper seats.  Probably last a lot longer . . . unless air filter maintenance is slack and you ride in sand, in which case the copper seats won't help.  That is my current position on the issue.  I think if we were competitive, it would be Ti valves and copper/beryllium all the way.  

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