how do i select a carb for a 1980 dr400?

Discussion in 'Old's Cool' started by meijer's trails, Jul 5, 2013.

  1. meijer's trails

    meijer's trails Been here awhile

    Joined:
    Jun 17, 2008
    Oddometer:
    497
    Location:
    S.E. Michigan
    i was wondering how does one select a carburettor for a 4 stroke engine?

    so my buddy has a dr400 1980 with no carb. im thinking of using a dr350 carb just because theyre plentiful.

    but what would the experts, you guys do?

    i remember seeing something about carb selection having to do with intake bore and displacement

    thanks
    jason
    #1
  2. qkenf4u

    qkenf4u Been here awhile

    Joined:
    Jul 25, 2009
    Oddometer:
    201
    Location:
    nice warm bike riding COTTONWOOD ARIZONA...
    find a carb that matches the bore size of a 1980 DR400 (32,34,36,38mm ??)
    then if youre really lucky it will be the same O.D. intake boot/airbox boot..

    you could try the 350 carb .. might have to play with jetting a little but maybe it will work perfect. def. worth a try..
    #2
  3. eric123

    eric123 Gott Mit Uns

    Joined:
    Mar 26, 2009
    Oddometer:
    1,504
    Location:
    Idaho
    Use a carb off a GN400, it is the same motor...
    #3
  4. Duck_Pilot

    Duck_Pilot Retired Roadracer

    Joined:
    Jun 13, 2007
    Oddometer:
    6,155
    Location:
    Denver 'Burbs, Colorado, USA.
    http://www.motorcyclespecs.co.za/model/suzu/suzuki_dr400s 80.htm

    This site says it's a 33 Mikuni, but does not specify type (slide-throttle/CV). The difference is a big one here. Since the DR was off-road only, I'd presume a slide-throttle - much better flow. Because both the GN and SP versions of that motor were street-legal, I'm certain they used the Mikuni CV, and in a bigger bore.


    http://www.suzukipartshouse.com/oemparts/a/suz/50d39782f8700229982f36ea/carburetor

    This site proves my suspicions...... it's a Mikuni slide-throttle. Here's the parts breakdown for ya. Junk-yard one, and jet to suit yer altitude.

    Yer welcome.
    #4
  5. meijer's trails

    meijer's trails Been here awhile

    Joined:
    Jun 17, 2008
    Oddometer:
    497
    Location:
    S.E. Michigan
    thanks duck!
    #5
  6. Duck_Pilot

    Duck_Pilot Retired Roadracer

    Joined:
    Jun 13, 2007
    Oddometer:
    6,155
    Location:
    Denver 'Burbs, Colorado, USA.
    Yer most welcome.

    Looks like OEM uses a twin cable push/pull setup with that bellcrank carb. If using the OEM airbox setup, you'll most likely need to copy that stuff. Using a 2-stroke type single-cable carb should work just fine, if the body is long enough to reach the airbox. That parts breakdown lists all the factory jetting, and at your altitude, that's gonna be the best place to start.

    Good luck.
    #6
  7. Andyvh1959

    Andyvh1959 Cheesehead Klompen

    Joined:
    Feb 16, 2012
    Oddometer:
    814
    Location:
    Da frozen tundra eh? 1.5 mile west of Lambeau
    A Mikuni VM36 has the same inlet and outlet spigots as the stock carb on the GN400. But you'd need a new throttle cable with the 90 degree noodle on the top to fit the VM36.

    But I think the VM36 may flow a bit too much air for the stock GN/SP/DR400 head. I am trying to jet a VM36 for my GN400 ice bike and it may just be too big of a carb. The SP400 used a VM33 carb as I think the DR400 did also.
    #7