32mm to 40 mm

Discussion in 'Airheads' started by centdukesfan, Jul 22, 2013.

  1. centdukesfan

    centdukesfan Adventurer

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    #1
  2. blaine.hale

    blaine.hale Long timer

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  3. centdukesfan

    centdukesfan Adventurer

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    do they work well with the high heat from the engine?
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  4. disston

    disston ShadeTreeExpert

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    Those intake runners are made for that application. I would assume they work with the heat from the engine.

    What doesn't seem too clear from your original post. Is this bike running a pair of 32mm carbs but one cylinder has a 40mm intake?

    There are disadvantages of mixing some of these parts but riders have been able to run 40mm Bings on 32mm heads. It's not recommended because there is a relationship between the carb and the way it feeds gas into the cylinder. The big carbs don't flow well at slow rpms. And if running 32mm Bings into heads with the 40mm runners you will have a mismatched set up also.

    But the worst set up would be a 40mm head on one side and a 32mm head on the other. I don't think you'd be happy with how that runs.

    It sounds like you are trying to do something like this maybe?
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  5. centdukesfan

    centdukesfan Adventurer

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    Ive got 32mm carbs from an r80 that are running into an r100 engine with a 40mm inlet.

    Does that make sense?
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  6. disston

    disston ShadeTreeExpert

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    OK. So both carbs are the 32mm variety and the engine has 40mm intakes on both sides. At least you have a balanced situation. It may run fine right away when you finish with new hoses because these should stop any intake leaks. Intake leaks make for poor idle and performance.

    You may have to play with the jets some but I won't try to predict what you will have. Good Luck with it.
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  7. centdukesfan

    centdukesfan Adventurer

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    my mechanic said i should be good on the carb situation, the complicated thing is getting the 40-32 reducer that is made for high heat.
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  8. disston

    disston ShadeTreeExpert

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    Those reducers are made for this application. Should be no problem.
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  9. airsmith

    airsmith airhead wrench?

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    what about getting some R80 or late model R100 head spigots and swapping out the ones on your heads to get the correct fit?
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  10. centdukesfan

    centdukesfan Adventurer

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    cant find anyone to source me a 32mm head spigot. Willing to listen if anyone has em!
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  11. robtg

    robtg Been here awhile

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    Why would you want to put 32mm carbs on big port heads?
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  12. centdukesfan

    centdukesfan Adventurer

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    swapped an engine when mine seized, plus the old r100 ran 32mms anyhow. Not too concerned about it.
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  13. AntonLargiader

    AntonLargiader Long timer

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    From the ad:

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  14. blaine.hale

    blaine.hale Long timer

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    I think he was talking about the ones I linked. They are most definitely compatible.
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  15. Airhead Wrangler

    Airhead Wrangler Long timer

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    I think that means you're not supposed to use it as fuel or oil lines. Silicone elbows and reducers are very commonly used on turbo and supercharged intakes where they're exposed to heat and fuel mist. You might want to clarify what the maker is actually saying there. eg: http://www.siliconeintakes.com/
    #15
  16. disston

    disston ShadeTreeExpert

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    I have to admit I didn't read all the way to the bottom of the ad. It does say not compatible with fuel and oil but earlier it says suitable for intake components. I'm at a loss to explain what they mean.
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  17. supershaft

    supershaft because I can

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    Most of the time it seems like everyone jumps on someone for not mentioning what model when it doesn't matter and then no asks the question when it does. Small port heads have carb spigots for both 32 and 40mm carbs. Last time I checked they were cheap. Big port heads don't have spigots for 32mm carbs. What heads does the OP have?
    #17
  18. robtg

    robtg Been here awhile

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    I think he is trying to put 32mm carbs on big port heads for whatever reason.
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  19. supershaft

    supershaft because I can

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    For wrongever reason? I have no advise for that. :D
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  20. Plaka

    Plaka Brevis illi vita est

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    All intake components upstream of the carb don't take fuel. Most don't take oil either although on the airhead the crank windage is just upstream of the carb.
    #20