Jump to content
Sign in to follow this  

2004 KX250F cylinder and valve replacement?

Recommended Posts

Has anyone ever done an athena 290 big bore cylinder and piston replacement themselves also valves. Just found out my bike was bored to a 270 instead of a big bore kit being put on and i have an athena 290 kit ordered with a kibblewhite valves and spring kit. The local kawasaki shops will not do aftermarket parts replacement, so i am thinking of doing it myself. Is this a major task?

Share this post


Link to post
Share on other sites

have u done any top end jobs b4....if u understand how the bike works...and the diff parts, and how they work...u can pretty much follow a service manual...the first time i did it was on a 05 yz250f.....now i can pretty much do all my stuff...

Share this post


Link to post
Share on other sites

have done valve and head work on auto engines many years ago in vocational school, but never on a bike. i have never done any real engine work on a bike.

Share this post


Link to post
Share on other sites

ok so u understand basically how it works...i would suggest doing it urself....u can get a service manual online by downloading it..i got one for free on the internet....also u can do a search....it will be just like installing an OEM valve train and Cyliner/piston.... if u want me to find some info for u...just pm me

Share this post


Link to post
Share on other sites

Boys How Are We? My 04' Kx250f Is Due For Top End Rebuild, And I Thought While It's Been Pulled Down I Might Invest In A Little Engine Work, I'd Love For It To Be More Pokey. Are These Big Bore Kits Safe? Already Spent Big $ On This Bike Last Thing I Want Is To Blow Her Up. IS IT POSSIBLE TO FIT 450 VALVES IN DA 250 HEAD HAS THIS EVER BEEN DONE? If Ya Can Help Us Out Beuty Please E-mail Me Cheers!

Share this post


Link to post
Share on other sites

With the Big bore kits, the pistons and cranks/rods tend to last not as long (depends how big you go, the max I would do is a 262)... If it were me I would want to just mod out the regular sized motor, you'll be surprised w/ what you can do.

What I would do

-High compression piston (13.5:1 or even 14:1)

-Race head, RHC if I may suggest, his porting, valves, springs and cam

-Pipe, something like the procircuit Ti-4

-Zip-ty race carbourator modification

Depending on what you do, you should be able to get 43-44 HP out of a 250f, so thats 10 ponies more than they came stock with a few years ago!

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×