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Thread: 300ex carb on a 250sx

  1. #1
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    300ex carb on a 250sx

    The topic came up when I suggested looking into doing this in another thread. The carbs look pretty close and I'm wondering how hard this may be. More importanly, will it help?

    Q#1
    What size is the 250sx carb?

    Q#2
    What size is the 300ex carb?

    Q#3
    Will a trike like the SX benifit from an accelerator pump?

    There's more Q's then that but it's a start. I'm checking but I think the 300ex carb is a 32mm.
    '02 Honda 416ex - A seasoned blend of 11 herbs and spices
    '04 Honda Recon - The yard machine and snow plow
    '88 Honda CR250R - Another chapter in my torrid all terrain affair

  2. #2
    conig is offline At The Back Of The Pack Arm chair racerAt the back of the pack
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    31 mm 350x accourding to this site., but the carb fits in the stock boot, so the bell at the fron't may be the only thing larger.

    300ex Carburetion 32mm piston-valve with accelerator pump

    250es has a 22mm carb and I remeber reading that 22 or 28mm was used for the big red but could not find anything to substantiate it. Hopefully some one with a service manual can tell us something here.

    the question is weither or not the slide is bigger on the 350x or not. some of the larger keighn and mikuni carbs have the same body and slide and have larger bells or air horns.

    350x on 250sx
    http://3wheelerworldforums.com/showthread.php?t=20416

    http://3wheelerworldforums.com/showthread.php?t=2792

    http://www.3wheelerworldforums.com/s...ight=250x+carb

    http://www.3wheelerworldforums.com/s...ighlight=300ex

    theres some info in the above links.
    1983 honda 70atc, als,ot done, need throttle cable and assembly. PM me if you have this.

    1985 honda es 250 big red.
    85 percent restore. 10x10 douglas 190's 22-11-10 at 489's. 12x7 itp c series 24-8-12 swamp fox. some accent painting. snorkel everything and a custom PCV system. moose air filter. cobra utility exhaust. 2.5 um wheel spacers.
    A trike to show up the modern utilitys


    2002 scrambler 400 2x4 uni pod filter, lots of weight shaving, v force reeds, HPD race pipe, 39mm pwk or 34mm, 12-1 head, trail porting, custom clutching, hole shots on t-9s +1 all around. works shocks . trail bike with drag tweeks.

  3. #3
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    the sx is 27 so the big red should be about the same size.

    Awesome according to some of the guys I can just take my SX jets and put them in the 350x carb
    Last edited by Tri-ZNate; 08-19-2005 at 01:39 PM.
    Nate

    The Myth, The MAN, The Legend
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    Quote Originally Posted by honda250sx View Post
    Fact: Dr. Death is Bob from Enzyte.

  4. #4
    conig is offline At The Back Of The Pack Arm chair racerAt the back of the pack
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    ok so 350x slide is 4 mm larger, but the external carb dimensions are pretty similiar, suposedly the 300es accelerator pump makes cold starting easier. Thats not as huge a problem down here in the south.
    1983 honda 70atc, als,ot done, need throttle cable and assembly. PM me if you have this.

    1985 honda es 250 big red.
    85 percent restore. 10x10 douglas 190's 22-11-10 at 489's. 12x7 itp c series 24-8-12 swamp fox. some accent painting. snorkel everything and a custom PCV system. moose air filter. cobra utility exhaust. 2.5 um wheel spacers.
    A trike to show up the modern utilitys


    2002 scrambler 400 2x4 uni pod filter, lots of weight shaving, v force reeds, HPD race pipe, 39mm pwk or 34mm, 12-1 head, trail porting, custom clutching, hole shots on t-9s +1 all around. works shocks . trail bike with drag tweeks.

  5. #5
    Join Date
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    Ok cool, I see some searching could have yielded some good info but this is good. I'm shocked that the 350x carb is smaller then the 250x/300ex carb. If I had a 350x I'd be tossing the 31mm and installing the 32mm with the accelerator pump. The accelerator pump can help on start up but it's mainly there to help out when you pin the throttle, it gives it a little more go. As for the SX 27mm to 31mm is a heathly jump but not near as much as I thought. IDK why, but I thought the 350x had a 34mm.
    '02 Honda 416ex - A seasoned blend of 11 herbs and spices
    '04 Honda Recon - The yard machine and snow plow
    '88 Honda CR250R - Another chapter in my torrid all terrain affair

  6. #6
    conig is offline At The Back Of The Pack Arm chair racerAt the back of the pack
    Join Date
    Aug 2004
    Location
    tallahassee FL
    --
    392
    whats weird is how many times I searched this website for the info I just posted. I start searching the same things on google and I get 3wheelerworld.com posts Ive never seen before.....Gottas love google.

    Im still thinking 300ex carb not becuase its bigger but they are cheaper and more plentiful, Id hate to rig something up on my red resto mod that someone else coyuld use for a 100% OEM resto. ya know?
    1983 honda 70atc, als,ot done, need throttle cable and assembly. PM me if you have this.

    1985 honda es 250 big red.
    85 percent restore. 10x10 douglas 190's 22-11-10 at 489's. 12x7 itp c series 24-8-12 swamp fox. some accent painting. snorkel everything and a custom PCV system. moose air filter. cobra utility exhaust. 2.5 um wheel spacers.
    A trike to show up the modern utilitys


    2002 scrambler 400 2x4 uni pod filter, lots of weight shaving, v force reeds, HPD race pipe, 39mm pwk or 34mm, 12-1 head, trail porting, custom clutching, hole shots on t-9s +1 all around. works shocks . trail bike with drag tweeks.

  7. #7
    Join Date
    May 2002
    Location
    Southeastern Wisconsin
    --
    3,658
    Quote Originally Posted by conig
    whats weird is how many times I searched this website for the info I just posted. I start searching the same things on google and I get 3wheelerworld.com posts Ive never seen before.....Gottas love google.

    Im still thinking 300ex carb not becuase its bigger but they are cheaper and more plentiful, Id hate to rig something up on my red resto mod that someone else coyuld use for a 100% OEM resto. ya know?
    Great point!!! I'd think that accel pump would be nice too.
    '02 Honda 416ex - A seasoned blend of 11 herbs and spices
    '04 Honda Recon - The yard machine and snow plow
    '88 Honda CR250R - Another chapter in my torrid all terrain affair

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