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. markc

    ChrisDC Guest

    Yamaha SRX.

    1 cylinder, 2 carbs. And...

    Dreadful warm start performance.
    ChrisDC, Jun 15, 2006
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  2. markc

    Dr Zoidberg Guest

    It was more like one and a half
    Mine was ok , apart from when one of the rubber manifolds split
    Dr Zoidberg, Jun 15, 2006
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  3. markc

    ginge Guest

    butbutbut - didn't Honda build a big single with two carbs at some

    I don't know about honda, but the SZR660 in my garage has 2 carbs, 1
    cylinder, and 5 valves.
    ginge, Jun 15, 2006
  4. markc

    FB Guest

    If you play with your brain too much, you'll go insane.
    FB, Jun 15, 2006
  5. markc

    FB Guest

    I don't have time to teach you about acceleration loads, I have to go
    and help the happy campers at the lake. And, besides, it's already
    happy hour over there and your brain is probably already well-impaired.
    FB, Jun 15, 2006
  6. Honda thingy err,, something or other, had a dual-choke carb feeding a
    single cylinder. XL 500?
    Grimly Curmudgeon, Jun 15, 2006
  7. OK, enlighten me. A bike will accelerate faster in in first than in
    The Older Gentleman, Jun 15, 2006
  8. Can I have a guess?

    Is it because the back load on the gearbox sprocket (and thus rest of
    the drive chain) is at its highest, in relation to the power put through
    it, on the limit in second?

    If by a 1,000,000 to 1 chance I'm actually right the world as we know it
    will cease to exist in a puff of illogic, so let's pray I'm wrong as

    Interesting point. I dunno. I just can't believe that conrods are
    strengthened purely because of second gear. Sorry. Load is load.
    The Older Gentleman, Jun 15, 2006
  9. Someone in the 1970s made an exhaust with a baffle-onna-pivot and a
    cable control, so you could open or close it at will. More for noise
    than anything else. Wish I could remember who made it.
    The Older Gentleman, Jun 15, 2006
  10. butbutbut - didn't Honda build a big single with two carbs at some

    Yamaha big singles have had two carbs for years.
    The Older Gentleman, Jun 15, 2006
  11. markc

    platypus Guest

    Alistair Laurie, who used to produce gorgeous Trident specials, would fit a
    sort of butterfly valve in his exhausts.
    platypus, Jun 15, 2006
  12. Using the patented Mavis Beacon "Hunt&Peck" Technique, Bear
    I stand by my point.

    And I still want one.

    Wicked Uncle Nigel - Podium Placed Ducati Race Engineer

    SBS#39 OMF#6 Enfield 500 Curry House Racer "The Basmati Rice Burner",
    Honda GL1000K2 (On its hols) Kawasaki ZN1300 Voyager "Oh, Oh, It's so big"
    Suzuki TS250 "The Africa Single" Yamaha GTS1000 Honda ST1100 wiv trailer
    Wicked Uncle Nigel, Jun 15, 2006
  13. Could have been him. Didn't he also make amazing Laverda specials?
    Elizabeth's Taxi comes to mind.
    The Older Gentleman, Jun 15, 2006
  14. OK, granted. I remember my old SR too. My 400 Four, OTOH.......

    Not to mention a long series of Honda twins. My 1978 CB200 had twin air
    filters, one either sid eof the frame, and the filter boxes were
    integral with the filter elements - they were just plastic covers.
    The Older Gentleman, Jun 15, 2006
  15. markc

    Bob Myers Guest

    Fine. Go ahead and spoil a perfectly good joke. Would
    you have been happier had I said "three or four"?

    Bob M.
    Bob Myers, Jun 15, 2006
  16. markc

    Bob Myers Guest

    Y'see, this is precisely the problem with trying to inject any sort
    of humor into a technical group. The moment you do, SOMEONE
    is just bound to trot out the "well, yeah, but didn't Tappet Bros.
    Motors, in their 1927 Feeblevitzer model, have an engine which
    used a secondary Thelmann wire in the reverse-framistat

    Killjoys. Each 'n' every one o' ya.....

    :) :) ;-)

    Bob M.
    Bob Myers, Jun 15, 2006
  17. The velocity of the air over each needle in a (small) two carb set-up
    should, I think, be faster than the velocity of air over the needle in a
    (large) single carb, thus making a more responsive/efficient engine. Its a
    bit similar to why big twins (think 916 through 999, Tl-series and SP1/2
    plus others) use injection over carbs - to flow enough air at high revs in a
    large cylinder, the carbs have to be so big that, at low revs they're
    shit.... Use two small carbs and that makes up the carbs opening surface
    area at high revs whilst keeping the fast airflow of smaller carbs for low

    Or something

    WavyDavy\(Mobile\), Jun 15, 2006
  18. markc

    James Clark Guest

    Didn't the Rudge radial valve single have 2 carbs as well?
    James Clark, Jun 16, 2006
  19. IIRC Yamaha's excuse is that the CV carb works for nice fine adjustment
    lower down the rev range and the slide one is for banging in fuill chat
    higher up.

    Big singles are notoriously finicky things once you try and get any sort
    of power out of them - Yamaha actually had to delay the launch of the
    XT500 by a year because it was proving such a troublesome engine to
    develop, and everything but everything was breaking in testing.

    Mind you, it was only the second four-stroke lump they'd built, so they
    can be forgiven.
    The Older Gentleman, Jun 16, 2006
  20. markc

    Ace Guest

    On Fri, 16 Jun 2006 07:16:20 +0100,
    Eh? They'd made loads by then, shirley? I can think of three twins off
    the top of my head: XS1/650, XS/TX500, TX750 (not UK). And I'm not
    even sure that the XS750 triple didn't pre-date the XT motor, although
    release dates might have been different in different markets.

    ..'_/_|_\_'. Ace (brucedotrogers a.t rochedotcom)
    \`\ | /`/ GSX-R1000K3
    `\\ | //' BOTAFOT#3, SbS#2, UKRMMA#13, DFV#8, SKA#2, IBB#10
    Ace, Jun 16, 2006
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