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Thread: XR250R Mod thread

  1. #41
    Join Date
    Apr 2007
    Location
    Sasazuka, Tokyo
    Posts
    922

    Default XR250R Mod thread

    Best carb available IMHO. Will be interesting to see the gains.

  2. #42
    Join Date
    Feb 2014
    Location
    Tokyo
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    1,592

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    Quote Originally Posted by Jav View Post
    Picked up an FCR33 so will fit that next week and start the tuning process.
    You should find this visual tuning guide handy :-)


  3. #43
    Join Date
    Apr 2014
    Location
    Meguro-ku , Tokyo
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    101

    Default

    Engines like the XR are restricted by design inside the engine you can get some increases from Carb and exhaust but is the vales and ports are restrictively small then physically the enging cannot pass anymore fuel gas etc etc. I had my KTM 400 ported by a well known engine tuner in Gotanda. Cost me 120,000 for engine overhaul carb set up etc etc The difference it made was mind boggling and this was on a competition engine that already had an open engine design. We went from a 170 Main to a 230 it pulls like a gorilla now opening up a restricted engine with the carb and exhaust in place magical things will happen

  4. #44

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    Quote Originally Posted by Neilb View Post
    I had my KTM 400 ported by a well known engine tuner in Gotanda.
    Details?
    KTM 690 E; DoD#1458

  5. #45
    Join Date
    Sep 2002
    Location
    Down by the river
    Posts
    17,155

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    Quote Originally Posted by Jav View Post
    Picked up an FCR33 so will fit that next week and start the tuning process.
    Where'd you get the carby?

  6. #46
    Join Date
    Apr 2014
    Location
    Meguro-ku , Tokyo
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    Guys what I meant from my last post was Carby + Exhaust + Engine porting would make a monster (Not taking away from Johns great services)

  7. #47

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    So reality check, an XR250R with the following makes 24hp

    2000 Honda XR250R modifications:
    XRs Only Mikuni Flatslide Carburettor 34mm Kit
    Uni Filter Dirt Bike Air Filter with High Flow Cage
    XRs Only Piston Kit ? 78mm / 10.5:1 / 284cc (Ceramic Coated JE Pistons piston)
    Ferrea one-piece stainless steel valves
    Kibble White Titanium Valve Springs
    Cometic Top End Gasket Kit
    Rick?s Motorsport Electrics 15-603 Hot Shot Series High Performance CDI Box (ignitor)
    XRs Only Crankcase Ventilation Kit (K&N filter)
    XRs Only Competition Exhaust Header
    FMF Powercore 4 exhaust pipe with spark arrestor removed due to a blockage



    My little beastie without big bore is unlikely going to see that much at the rear wheel.
    Still it can be better than it was, and in fact it is. Quite a bit better IMHO, in terms of response.

    You can see the power comes on faster and the bike has picked up approx 8% or 1.6hp. There is a restriction
    i need to sort out killing things from 8500rpm. Still looking at that.
    ( Chart temporarily removed )

    Torque is likewise slightly improved.
    ( Chart temporarily removed )

    Looking forward to the FCR and seeing what it can do. Hoping the 8500rpm issue is cured with some
    porting on the inlet manifold and the addition of the FCR.

    On the dyno, the bike feels much more responsive ie the suspension compresses more when power is
    applies and removed, than when stock. Still have to try it on the street.
    Last edited by Jav; 03-06-14 at 01:00 AM.
    Apexmoto Inc - Dyno tuning, engine/chassis/suspension upgrades, repairs, shaken, tires & changing with balancing, graphics printing, stickers, media blasting, painting & powder coating.

  8. #48
    Join Date
    Sep 2002
    Location
    Down by the river
    Posts
    17,155

    Default

    Sounds good, looking forward to seeing it on a ride.

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