250X BigBore & "R" Head

Last year I picked up a new '09 250X and immediately put the Athena 280cc big bore on it and added a Hot Cams Stage II cam.  I also took off the emissions apparatus, did all the CC mods including the pink wire, and drilled a hole in the silencer baffle to let it breath a bit better.  I really like the bike.  It has good low end chug which allows me to pull just about any hill without the wheel spin issues that my 450 would have.  When I go full throttle, I can feel the additional pull the cam provides.  In all, it is just about perfect, but I think I would like a little more.  So... I am considering putting on an '07 "R" head I have to give it a bit more snap and overrev, and here is my question.  Do I go with Stainless Steel intake valves, or change the seats to BeCu and use Titanium valves.  I understand the Ti setup will definitely rev quicker and give more rpm, but will it be that noticeable?  There is about a $300 cost differential that could sway me to the SS valves if there isn't that much difference.


I am an experienced rider who has won a few district enduro and one state motorcross titles in my day, but I am now an old fart who is slowing down.  I still like to go fast and enjoy the rush of the bike when it pulls hard, and for technical trail riding this is going to be my go to ride.  Any experiences or knowledgeable expertise is most welcome.



Wouldn't spend money on the 07r head, the 09 head is good.  The setup you have now is held back by the muffler, drilling the end plate helped but not enough. If you had an earlier version X you could pull the baffle out and prove it to yourself. I don't like loud, but it really woke up the 280 I ran. 

There are trains of thought on the aftermarket exhaust question.  I believe there's more evidence that shows a more open exhaust moves the power from bottom to mid/topend moreso than adding power.  I bought my 07 with the baffle removed, but put it back in for sound concerns.  Immediately picked up enough bottom end to make it a whiz to wheelie.


Depends on what you want.  Here in Maine on our slow, steep, rocky terrain I'll take bottom all day.  I see the OP is in AZ, so removing the baffle or going aftermarket may be just the ticket.  I just weighed the stock muffler (baffle in) at 7.2 pounds.  I also have an FMF Powercore4 which tags out at 4.7 pounds.  I'd love to have the sound control and bottom end of the stocker but weighing 2.5 pounds less.  Doubt that's gonna happen.  


I've heard that the 07+ X heads are very similar to the R heads, so prolly not a lot to gain there.


Sorry, can't chime in on the valve issue - no experience.  Good luck.

Edited by dukesilver

I haven't had to do my top end as yet but I'll be going SS valves once I do. 08 "R" head and 08 "R" cam. I'll be going to the 280 kit at the same time.


I have an FMF Ti Mega Bomb system. It's pretty quite. I expected it to be a lot louder.


PS, mine's a new 04 model, hence the 08 "R" top end. There's some great Info here. "Disco" has been ridding 250X's for a long time and has tried many different cam options etc. Well worth a look IMO. "Spock"  is sponsored by the Australian factory Honda team so knows his stuff also.



Edited by AddictedToBling

07 r head popular because it had more meat for porting. later years only got better and more refined.  Early X heads had bigger ports and may even work better for big bores?  I went from a big port 06 head to a smaller port 07 head and truthfully couldn't feel any advantage, running both a 49 state X cam and 07 R cam. 250cc and 280cc.  My point, if your early head is good no reason to switch. The OEM replacement casting for a early year X is a 07 R casting.

Edited by highmarker

Create an account or sign in to comment

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

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now