Why is there 1 carb per cylinder when a car has one carb for multiple cylinders?

Discussion in 'Motorbike Technical Discussion' started by markc, Jun 11, 2006.

  1. Absolutely not. Fess up, say "I goofed", move on. Well done.
    The Older Gentleman, Jun 17, 2006
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  2. markc

    peter Guest

    Gilera 'bialbero' Nordwest/RC singles use the same Teikei twin choke
    carb. Simplest tuning mod is therefore to junk it and replace with twin
    CR33 Keihin smoothbores. 3 or 4 BHP instant improvement when properly
    jetted. They even start better.

    I read somewhere that despite an effective choke area of 70mm it still
    works better than one 70mm choke carb (now that would be an awesome
    sight) - twin port head I suppose.

    Can make for a little inflexibility at low revs.In fact a little
    judicious fiddling allows you to put the slides just a tad out of synch
    so that one opens very slightly before the first but they are both wide
    open at full throttle.A more free flowing exhaust also seems to help.
    Standard Nordie (558) 45BHP ish. Nordie bored to 604, gas flowed head
    higher CR, twin CR33s and a 'race' exhaust = 55 BHP (dyno). With
    special cams you can get to 60+ but then the crankcases split between
    the main bearing and the balance shaft (whatever gear you rev it too
    hard for too long in).

    Sorry if this eventually get duplicated but Demon's news server is
    still down and the original post last night has not appeared yet.
    peter, Jun 17, 2006
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  3. markc

    deadmail Guest

    Here's your answer:

    They've all been hacked around with.
    deadmail, Jun 17, 2006
  4. markc

    sharkey Guest

    The SRX250 has one-and-a-half carbs ...

    sharkey, Jun 17, 2006
  5. markc

    sharkey Guest

    Damn! Beaten to it by a crustacean!

    [In case anyone is wondering: from memory, it's a four-valve single with
    two separate inlet tracts, and a very odd carb which looks like a slide
    carb and a CV carb next to each other and sharing various linkages and a
    float bowl. One feeds each inlet valve. I have no idea why.]

    sharkey, Jun 17, 2006
  6. They were ace bikes indeed - slightly gutless below 6k, but really,
    really solid. The XJ750 Seca that followed was a huge disappointment -
    some markets got an XJ750 which was identical to the 650 in all buit
    capacity, and it was a shame we never saw it.

    Not always. Like many Hondas they were susceptible to 'oil neglect', but
    if you changed the lube religiously they were great.

    Again, dodgy carburation was their downfall. They were jetted lean for
    the Yanks and then Honda had to stick accelerator pumps on to make up
    for the wet bottom end response. Mine was utterly stock, and ran
    appallingly weak at the top end. I went up two sizes on the main jets
    and it was perfect.

    They steered superbly, did 120, were very comfy, well braked and easy on
    fuel. I wouldn't mind another (sorted) one.
    The Older Gentleman, Jun 17, 2006
  7. Nope. Dual throat carbs have sometimes been used in cars because they
    give better mixing over a wider range of throttle and revs. The reason
    they're not used on bikes is that the carbs are often jammed for space
    and nobody cares much about mpg.
    Chris Malcolm, Jun 17, 2006
  8. [/QUOTE]
    Better mixing over a wider range of conditions, giving a smoother
    torque curve and either better mpg or more torque depending on taste.
    Chris Malcolm, Jun 17, 2006
  9. markc

    Bob Myers Guest

    The tricky thing, now, will be to design an engine with
    one-and-a-half cylinders to go with it....

    Bob M.
    Bob Myers, Jun 18, 2006
  10. markc

    Andy Bonwick Guest

    The pistons made it over here which made for very easy big bore kits
    for XS2 Yams. Liners were dirt cheap and the pistons were the same
    price as standard items.
    Andy Bonwick, Jun 18, 2006
  11. markc

    rhavindog Guest

    rhavindog, Jul 8, 2006
  12. markc

    platypus Guest

    You could power it from a wind turbine in the exhaust flow. The real
    problem would be getting the signal into the pipe.
    platypus, Jul 13, 2006
  13. markc

    ChrisDC Guest

    I'm sure an old book I read many years ago had a switched open/muffled
    exhaust in the hero's car. Might have been...

    The Saint?
    Bulldog Drummond?
    James Bond?
    ChrisDC, Jul 13, 2006
  14. markc

    kzjohnorr Guest

    kzjohnorr, Aug 23, 2014
  15. Fuckwit.
    The Older Gentleman, Aug 24, 2014
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