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Thread: KX250 conversion guys please help me out.

  1. #1
    old honda dealr is offline At The Back Of The Pack Arm chair racerFirst time rider
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    Jan 2005
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    215

    KX250 conversion guys please help me out.

    I bought a 98 KX250 motor off of ebay for my 86 Tecate T3. I got the electrical harness with it as well. Now what I am wondering is what kind of sprocket setups are you guys using. This bike is gonna be my sand racing bike and will probably be using 20 inch haulers. Any comments for sprocket combo's? Also any additional info on what I will need to outrun a buddies 05 Yfz450 would be nice.


    MOds so far are as follows:

    40mm carb
    DG pipe
    uni filter and 20 inch haulers

  2. #2
    Join Date
    Jun 2004
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    potsdam ny
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    1,227
    ummm, a 98 kx250 motor should be able to outrun a stock yfz no problem....start running a 1:3 sprocket combo...that would be like 11T front 33T back or anything like that...then work from there, i dont know how wide or narrow that trannies gear set is gonna be but im guessing narrow, so you might want to run a little lower final drive like 1:2.8 or something....i think www.sidewindersprockets.com has a chart...
    1985 Honda ATC250R drag trike with s/t kit and full drag CR hybrid motor and drag chassis...
    1986 Honda ATC250R daily rider fully modded engine, +4 swinger,etc...
    1997 Polaris Storm 800 triple, boyesen reeds, dg individual silencers, 240 studs, 123mph on radar...

  3. #3
    Join Date
    Nov 2004
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    Waterloo IL
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    2,701
    I would just get a nice carb, pipe, mill the head and have the cylinder ported you should be good to go then. I personally don't think you have a chance if you leave the motor stock. My buddy has a 98 YZ250 it has Pro- Circuit exhaust, air filter, jetted, Pro-Lite piston, milled head (has to run on 110 octane). We are neck and neck but I can beat him every time with my 450R. Another friend has a 2000 CR250 with the same mods and he can beat me by inches, it's almost dead even. If either of those motors were in an ATV I wouldn't have a problem dusting them.
    08 Outlaw 525s
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  4. #4
    Join Date
    Dec 2002
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    749
    I never had a problem and liked running 14/37 gearing when I had a 95 KX250 motor in my Tecate. It was perty damn fast for running a 34mm Tecate Carb lol. It put a whooping on several LTZ 400s. The only modifications done were carbon fiber reeds which Id reccomend. Now the KX Tecate vs the Tri-Z 426 I made there is no comparison. The KX Tecate would be left in the dust. But Im sure you could make the KX Tecate run scary fast with ease. Is the DG pipe for the KX motor?
    3WheelsForever / Virgil
    TrikeFest 03, 04, 05, 06, 07

    1985 Honda ATC350X - TF2015 Project
    YZ426 Hybrid Trike - On the back burner

  5. #5
    Join Date
    Nov 2004
    Location
    Waterloo IL
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    2,701
    Quote Originally Posted by 3WheelsForever
    I never had a problem and liked running 14/37 gearing when I had a 95 KX250 motor in my Tecate. It was perty damn fast for running a 34mm Tecate Carb lol. It put a whooping on several LTZ 400s. The only modifications done were carbon fiber reeds which Id reccomend. Now the KX Tecate vs the Tri-Z 426 I made there is no comparison. The KX Tecate would be left in the dust. But Im sure you could make the KX Tecate run scary fast with ease. Is the DG pipe for the KX motor?
    I gotta see this Tri-Z 426 post some pics. Start a new thread if you like. That thing has to be totally badass. How does it stack up to an ATC500R?
    Last edited by Blown 331; 07-12-2005 at 10:28 AM.
    08 Outlaw 525s
    07 CRF70
    04 Harley FLHRCI
    04 TRX90
    03 XR650R
    03 400EX- XR650R engine
    02 XR100R

    01 Banshee
    00 XR50R
    00 XR70R

    99 PW50
    99 JR50
    96,95 Sportsman 400
    95 Xplorer 400
    94 Indy XLT
    87 Trail Boss
    86,86,86,86,86 Scrambler

    86 TRX70 x2
    85 ATC350X
    85,84 ATC250R

    85 Red Tecate
    85 LT50 x2
    84 XR500R
    84,84,84,84,83,82,80,79 ATC70
    82,79 XL500R

    83 ALT50
    79,78,77,77,76 XT/TT500
    76,75,74 XL70
    72,71,71,71 SL70

    72 Harley FX
    72,71,70,70,70,70,70 CT70H
    72 SL100
    70,69 Z50

  6. #6
    old honda dealr is offline At The Back Of The Pack Arm chair racerFirst time rider
    Join Date
    Jan 2005
    Location
    texas
    --
    215
    No the dg pipe was for the tecate motor. I know it will need to be redone or I will have to buy a pipe for the kx250. 3wheelsforever, When you had your motor was it faster then the yfz450's?

  7. #7
    Join Date
    Dec 2002
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    749
    Didnt have any 450s around here then so I couldnt tell ya. Blown I couldnt tell you how it steps up with the ATC500rs never got a chance to race them at TF05. Ill have new pics of it up as soon as I get the new rear end on it.
    3WheelsForever / Virgil
    TrikeFest 03, 04, 05, 06, 07

    1985 Honda ATC350X - TF2015 Project
    YZ426 Hybrid Trike - On the back burner

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