Jetting advice Athena 280 kit

Hi, i'm busy fitting an Athena 280 kit on my X, anyone got any advice on base jetting for this build. It got a flowed head, 07 R cam


There's a lot of varibles to just tell you a baseline. Your climate,elevation,mods you have done,CCC's,pipe,etc.Generally you go down 2 sizes on the main with a BB.But if your still running stock jetting with your new cam and ported head you'll probably want to go up a few sizes.160-165 main 42pj.

I had a similar set up last year, 48 pilot a 07r needle on the 4th clip from top and a 160 main,it ran well with no problems,on the dyno it showed rich on the air/fuel ratio at both the bottom and top,i would probably go with a 42 pilot same needle and a 152 main.

i've just finished this years bike but have not had chance to test it yet,i should know the figures in a couple of weeks time,pm me if your interested and i will let you know the results

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

  • Similar Content

    • By Connor Wright
      Hey I have a crf250x 2005 I was riding today in top gear flat out and when I slowed down blue smoke just poured out the exsaughst then I happened to open the air box lid and saw it has what looked like engine oil in it then took out air filter and noticed that there was splatters of engine oil on the inside and that and the channel that goes to the carby had engine oil all over it.
      Also bike got a top end rebuild 15 hours ago
      The engine still runs good and sounds normal
      why would this be happening on a resonabley fresh engine
    • By mikemcbride
      Hey everybody. Quick question for y'all. I recently went riding and about halfway through my ride my motor seized on my '07 CRF250X. I haven't investigated it much but I checked the oil when I got home and there basically was none so I'm assuming that was the culprit. There weren't any metal shavings in the filter or on the plug either. At this point I'm trying to decide to rebuild the motor or just sell the bike as is and let the next buyer deal with it (they would know the deal obviously.) I feel that I'm pretty mechanically inclined but rebuilding a CRF engine is a bit out of my league and I assume paying a shop to do it would put me out more money than the bike is worth. So, I have this question to ask; what would be a fair price for a pretty dang nice shape 07 CRF250X, with a seized motor with an unknown extent of internal damage?
    • By ThomasM.
      selling Hot Cams Valve Shim Kit that i bought for my 2005 crf250x, will also fit crf250r.
      used 1x 1.30 and 2x 1.55 shims. the rest is still there.
      $60usd shipped in the usa or canada
      please contact me for pictures or if you are not sure if it will fit your bike
    • By TerryA
      I have two rides in on my new Rekluse auto clutch and I have to say I'm very pleased. The install wasn't hard, but was pretty much a all afternoon sort of project. I also installed a left hand rear brake kit and a two finger cluth over-ride with the adjuster on the perch (which I rarely seem to need). It has all worked great right from the beginning. After struggling to get up a tricky hill in first gear, I tried it in second and the autoclutch helped me clean the hill easily. Not having to worry about clutch action in techinical sessions has also eased fatigue and just made it more fun all the way around. I ride mountain bikes alot, and having both brakes up on the bars has also been nice as it makes for a set-up just like the bicycle - in fact I like that as much as not having to worry about clutch manipulation. The brake on the bar is especially nice on tricky downhill sections where you need to paddle, such as nasty rock/rut stuff. So first impressions are that it was worth the investment -making the ride more enjoyable and easier at the same time!
    • By Mikey560
      I was driving the bike for 15min or so and all of the sudden the bike stalled. I tried starting it again with no luck. I took the spark plug out to see if there is spark so i ground the spark plug to the frame and there is no spark. I even put a new spark plug in the bike and still nothing. Any ideas what i should check??