Dual Carb System

Discussion in 'Performance Mods' started by DuctTapedGoat, Jan 25, 2011.

  1. DuctTapedGoat

    DuctTapedGoat Active Member

    Hey, I'm considering taking a dual brake setup and combining it with throttle setups. I want to do a dual carb! I know I'm looking at some VERY SERIOUS tuning, but this is something I want to do just to prove it can be done.

    I know boost bottles have been talked about a lot recently, and after some deliberation I've decided that the best way in my own personal opinion to get the concept itself working in all peak efficiancy, a second carb is the solution.

    Anyone have any advice, tips, opinions, questions?

  2. gothicguy64

    gothicguy64 Member


    i believe 16 to 19 mm is the go for 1

    so i guess a 9 mm carby is what ull need

    an a 9 mm is rc car size

  3. HeadSmess

    HeadSmess Well-Known Member

    um, yes, it will woooork...but why? i see absolutely no benefit on an engine like this...

    if it was fitted with a 32mm keihin then, yes, maybe two 18mms side by side could be better, but...

    if two carbs was better, it would be done on a constant basis! theres only one bike that did it and thats the honda XR! and it was silly! and it was returned to normal in later models!

    maybe a twin barrell style thing...but where to find one?

    oh well. your money, your bling. not my prob :D
  4. DuctTapedGoat

    DuctTapedGoat Active Member

    Lol, I'm not worrying about what it'll cost. I just want something fun to mess around with. Twin carbys are always tough to tune, I just haven't ever heard of it on a two stroke. Not that it NEEDS to be done, I'm just saying it'd be fun. And it ties in with a HUGE HUGE HUGE mod which I'm posting in product dev section.

    I've been thinking about doing it two ways, one by way of a T fitting and have one on the left one on the right, and the other way would be inline, just using a coupler.

    I've seen working boost bottles, and they weren't solidstate bottles, they were accordion style bottles on the end of the hose which actually breathed from pressure, not relying on a useless vacuum. That's how to emulate the twin barrel.

    This would just be a way to increase air intake, increase fuel intake and at the same time take advantage of a ported exhaust.

    There is benefits, and they will be running individually. Plus it's one of the parts to a grander scale of mod, which is in product development section.
  5. wheelbender6

    wheelbender6 Well-Known Member

    If you want two carbs; do it. You see plenty of things on the motors at car shows that are not practical but look awesome.
    Be advised that you will lose some bottom end power with a pair of jugs. You may be able to make up that loss with a reed valve.
    There is a post somewhere showing a China motor with a home made dual carb setup. I'll try to find it.
  6. motorpsycho

    motorpsycho Active Member

    I would do it just for the looks, because 2 carbs look cooler than one.
    You could use 2 n.t. carbs jetted down very lean.
    You would have to build a Y intake manifold and make a 1 into 2 throttle cable.
    It would not be that difficult to make all the parts, the jetting would be the hard part.
  7. DuctTapedGoat

    DuctTapedGoat Active Member

    I'm not sure which would be better - to run dual throttle, or to do independent throttles.

    Jetting is what it all comes down to here, unlike a 4stroke with dual carb, there's not any timing issues to worry about, only jetting. They'd have to jetted really lean! But, they're cheap enough to where getting them from SBP wouldn't be a problem at all - even messing around with independent throttles and different sized jets on each carb.

    This wouldn't serve much great a purpose, but I think it'd be fun, especially on a long ride having a lot finer tuning on the go with no tools. As well, I can just turn each carb on or off at will, so it's not like I'm stuck with two carbs at full throt.

    Definitely let us know if you find that link!
  8. a/c man

    a/c man Member

    Here's a couple of pics a forum member posted with his dual carbs.
    Clay is one of the best 2 stroke bike guys out there.
    I believe he goes by foureasy on the other forum.


    Scroll down the page to post #4

  9. kaino(Aus)

    kaino(Aus) New Member

    Holy s##t twin carbies. thats link is sweet. im makin one tomorrow.
  10. rustycase

    rustycase New Member


    It may not be too bad an idea, dtg...
    Try progressive linkage.
    One small tube will get you bottom end, and the pair wide open will give you superior top end.
    ...just might work!
    I looked at Clay's pics... he sold the first setup and went with longer runners for the second version. I like his pipe running under the frame...

    Good luck with carbs,
  11. hammer5312

    hammer5312 Member

    I wonder how hard it would be to set-up a dual carb system with progressive linkage?
    kind of like a Rochester 4 bbl carb.....or like the V-max or like the Taurus SHO....
  12. DuctTapedGoat

    DuctTapedGoat Active Member

    Technically it'd be easy - we're dealing with float bowls and barrels.

    Though, the more I think about it, it might be best to use two carbs inline, and have an air ram. That's the only purpose an air ram would really be necessary too.
  13. rustycase

    rustycase New Member

    I guess a Q-jet spreadbore is kinda along the idea I was thinking, Hammer...
    The Vmax is a twin cyl mcycle, right??? and probably twin carbs??? with a balance tube??
    Got this vfr out in the yard that is Vfour and 4 carbs... it's prob is electronic controlled ignition modules.
    AFAIK the Taurus SHO is efi... there's probably someone out there doing efi on a little micro motor, but I haven't seen it yet...

    Things dawn on me, from time to time... lol I got a buncha dumb stuff out there, including the yammie thumper that has a dual carb. Among the most complicated looking things I've seen that I haven't even taken it apart yet. lol

    Has anyone tried an outboard motor carb?
    They are already jetted for mix.
  14. tothebeach

    tothebeach New Member