04 250x Power Upgrade
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    chippy
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    04 250x Power Upgrade

    by chippy » Sat Aug 02, 2014 11:12 am

    I am looking to turn up the power on my 250x. My bike is stock with the exception of a JE hi comp piston and KW stainless intake valves. Airbox mods, pink wire and exhaust diffuser mods. Carb has been jetted with AP mod. It runs good, no bog or hesitation. Smooth power delivery, just a little boring for my taste.

    What do you folks suggest?
    R-head and cam? (05?)
    Aftermarket exhaust?
    Porting the stock X-head?

    I ride alot of mountain single track mixed with some high speed desert/trails at medium altitudes. (3000-6000ft.)
    Any thoughts from the experts?
  • hall_philip
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    by hall_philip » Thu Aug 14, 2014 5:45 pm

    I am currently running an 08 R head with 08 R cam, KW steel valves, vertex R piston, open airbox, power core 4 silencer, and power bomb head pipe. next rebuild will include a big bore to get some bottom end power back, I find myself beating up my clutch, as that will also be getting changed out for a rekluse core exp 3.0 unit. As she sits now, good power on the top end, lacks in the bottom. still a fast bike, if your really looking for that much more power get a 450. I ride similar conditions and for me the 250 is the way to go.
    also your better off porting the R head than the x head.
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    chippy
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    by chippy » Thu Aug 14, 2014 6:11 pm

    Thanks for the input.
    I should really just leave it alone! The power is smooth with no bogs or hiccups and this works well on mountain single track. I just wish it had a little more "hit" in the mid-range. She's a little boring when you drop down on the Forest Service roads. It will be time to do a new piston this winter and while it's apart.... ;)

    A 450 is a better solution, but is just too much bike for this type of riding. Honestly, a trials bike would be better suited for most of our trails!
  • hall_philip
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    by hall_philip » Sun Aug 17, 2014 1:06 pm

    I see you eye to eye on the trials bike, I have been wanting to get one for some time, but they really lack in the top end power department. lol would be a blast in a play park though. I love throwing my 250 around and showing off for my buddies.
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    crfsonly
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    by crfsonly » Fri Aug 22, 2014 2:46 pm

    a great "tweener" bike between the 250X and the 450X is the 280X:

    * Athena 280cc big bore kit
    * 2007 CRF250R head with KW stainless valves
    * '08 R cam or equivalent
    * Pink wire mod

    We've been putting this "kit" for years and the results are outstanding. You can read some posts in our forums on the results. Great power everywhere while still in the 250X package.

    Ken
    OEM Parts for Honda - Yamaha - Suzuki - Kawasaki: http://yeltrik.com
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    chippy
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    by chippy » Wed Aug 27, 2014 12:18 pm

    Thank you Ken.

    2 questions:
    Do you have to machine the cases to install the kit? (I recall hearing the 04 required machining?)

    Do you sell these parts as a complete kit?

    Thanks again,
    Chip
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    crfsonly
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    by crfsonly » Wed Aug 27, 2014 12:20 pm

    No, the Athena is a drop in product. No case machining necessary.

    We don't sell it as one kit but if you need links to the individual parts let me know.

    Ken
    OEM Parts for Honda - Yamaha - Suzuki - Kawasaki: http://yeltrik.com
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  • taylorcraft
    Posts: 48
    Joined: Tue Jan 21, 2014 5:51 pm

    by taylorcraft » Thu Aug 28, 2014 11:47 am

    Here's my 2 cents worth: I have a 04 X that needed a valve job. Got a 09 R head with KW exhausts and Del West intakes alloy seats, 08 R cam, 13.5 JE Piston, FMF Power Bomb header and Powercore silencer, CCC mods.
    The bike absolutely rips, easily picks up the front in the first four gears, chugs along in 2nd and 3rd in single track, no bog. Everyone who rides it thinks it is a big bore.
    I run gearing from 13/51 to 14/45 and it handles everything. Not cheap but I would do it again. CRF Only sells all the parts.
    I know longer fear the color orange!
  • Big Freedom
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    Joined: Wed Nov 26, 2014 1:07 pm

    by Big Freedom » Wed Nov 26, 2014 1:21 pm

    [quote="crfsonly"]a great "tweener" bike between the 250X and the 450X is the 280X:

    * Athena 280cc big bore kit
    * 2007 CRF250R head with KW stainless valves
    * '08 R cam or equivalent
    * Pink wire mod

    We've been putting this "kit" for years and the results are outstanding. You can read some posts in our forums on the results. Great power everywhere while still in the 250X package.

    Ken[/quote]
  • User avatar
    chippy
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    by chippy » Sun Nov 30, 2014 2:10 pm

    So what exhaust do you run with this set up?
    Can you expect decent performance with the stock system?
  • rroeckel
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    by rroeckel » Wed Dec 24, 2014 2:12 pm

    What do these big bore kits to the longevity of the bikes? I've heard/read the extra power over stresses the crank/lower bearings, this is a concern to me.

    In my mind, it's only a couple of hp, so it shouldn't make THAT big of a difference but I'm no expert.
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    crfsonly
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    by crfsonly » Thu Jan 08, 2015 1:14 pm

    Those stories of bottom end issues are not true. We've been doing this for years with hardcore riders and not a single bottom end, or top end, issue.

    Ken
    OEM Parts for Honda - Yamaha - Suzuki - Kawasaki: http://yeltrik.com
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