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HI everyone,
CRF250R 2005 Stock

rebuilding by bike and as I bolted the engine back into the frame I thought i'd do a compression test, I understand the manual states it should be done warm and should be around 57 psi, but I've done it cold as its not yet ready to run. I got a reading of 25-30 psi whilst cold and i'm concerned the valve clearances are within tolerance. is the difference between warm and cold rearly 27psi? or have I got a bigger problem.

cheers

Need a bit more info on the "rebuild" , as your description is a little vague , were the valves done ?? , are you positive the timing is correct ?? , was the ring gap staggered and placed according to the manual ??? , did you check the compression using the procedure the manual said to do to check it ??

Rebuild may not have been the right word, break down and clean is what I did, replacing worn parts.

Anywho I decided to pull the head and found a leaky valve which would explain the low compression (hot or cold) just debating now weather to have the SS seats recut and wether I should get 4 new valves or have these refaced.

If you are not racing seriously , then Stainless is the way to go , its 1/10th the maintenance and gives you peace of mind that the valves are not going to go out in a season like Titanium sometimes do , I have 13 years on one set of Stainless Intakes without a valve adjustment needed on my 06 450X , and another Intake set I did in 2016 (with springs) that is still exactly where it was when I first set the lash at assembly on my 02 450R

I track ride that bike every weekend from usually Feb. till October and have done so without needing a adjustment yet ... the week before last I track rode Thursday,Friday,Saturday and Sunday , then rode again this Sat/Sun , like I do most every weekend as long as the ground is free of snow , I enjoy the fact that all I need to worry about is freshening up my suspension once a season and keeping the oil changed every 6-10 rides (Synthetic) , and spend the rest of my time riding instead of replacing engine parts or adjusting valves

To somewhat directly answer your question , it is basically up to you and your budget , if you can afford to do a complete valve job then do it (Ken *the owner of this site* does excellent work and also offers complete heads set up and ready to install) .... if the Exhaust are still in spec , then just do the intakes , as Exhaust will outlast Intakes (Titanium) by several seasons usually ....... I have only done Intakes on both my bikes and have not had to adjust the Exhaust since I have had each bike (the 06X I got new in 05 , and the R I got in 08 , and have not needed to shim the Exhaust on either yet ..... Either way , you can't go wrong .... , and you do not "resurface" the valves , they are a "wear part" and are only replaced , you resurface the valve Seats by either recutting them or replacing the seats with new/better ones ......