Jump to content
Sign in to follow this  

yz250f rebuild help

Recommended Posts

So the other day I pulled the old 2004 YZ250F out after moving to Colorado from Hawaii so...


the 1st problem started with ALTITUDE over a 6000 ft difference. I knew i needed jets so i went to the local shop here and they hooked me up.


the 2nd problem after i got it all together, and rode around seemed flat at the top end and i started to get cherry pipes. 



so my dad said valves, you should check to see if its getting enough air. 

so i pulled it apart myself and start getting my gaps for re-shimming it.


the 3rd problem comes along all the valves need adjustment. 


left exhaust was 0.15mm 

right exhaust was 0.15mm


left intake was 0.00mm        (could not get a 0.04mm is smallest feeler gauge i have)

center intake was 0.00mm

right intake was 0.09


specifications for the maintenance manual

exhaust is 0.17mm to 0.22mm

intake spec is 0.10mm to 0.15mm 



so i pull the center intake shim to see what size i need to put in and its 120mm, the smallest shim


so im guessing i need new valves??? 




????????do i need to get all new valve assembly ( valve, seals, seats, springs, and retainers?)

or just some parts 


???????what kind of head work does this need before i install new valves??? (valve seat cutting) 

what shop is good?


????????steel vs titanium?


??????? will any valve work for a yz250f or do i need to get a measurement?


since I am going to rebuild the valve train, im going to toss a new ring and piston in also. 


?????? brands should i use for ring and piston ?


should i send my cylinder off also?



thanks for the help in advanceimage (1).jpegimage (2).jpegimage (3).jpegimage (4).jpegimage (5).jpegimage.jpegphoto (1).JPG

image (1).jpeg

image (2).jpeg

image (3).jpeg

image (4).jpeg

image (5).jpeg


photo (1).JPG


Share this post

Link to post
Share on other sites

I prefer OEM for all internal parts. You should be able to get away with just valves and the correct shims to bring them into spec. Only you can tell if the valve stem seals need replacing, but if your going to the trouble of rebuilding the complete top end, just throw them in there to be safe. Don't forget a new cam chain while your at it.

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