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Thread: air horns for my 75 stinger

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    Default air horns for my 75 stinger

    howdy,

    my dad (joe mccauley) has already extensively posted pictures of our allison and stinger, ill cut straight to the point


    i want to tune the stinger, and ive already made one air horn for the carbs. how many sizes up should i go with the high speed jets and is there some formula for calculating that, you know, taking into account the length of the air horn etc etc...

    know i need to rich it up, and i understand the principle of it all, i just want to be careful and not have a nice little rattling sound of the rod clanking around in the crankcase..







    Why would anybody want a Yamaha when there's an E-Tec?

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    Sam Cullis Mark75H's Avatar
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    From what I understand about reed valved 2 strokes, reeds pretty well dampen out any significant intake tuning.

    I don't know of any formulae or rule of thumb that gives any working results.

    I suggest you try your set up and see for yourself.


    What formula did you use to arrive at the length you produced?
    Since 1925, about 150 different racing outboards have been made.


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    john calley told me about air horns and gave me the idea originally, he told me i can also put in grooves at the bottom of the horn to channel the air even more.

    i just kind of eye balled it ( *grin) i started out with one and a half inches of material and down sized it some more. its got more than enough room under the calling, i checked.

    i just looked on google for some pictures of air horns and used them as a model. then it was calipers and a small tolerance...
    Why would anybody want a Yamaha when there's an E-Tec?

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    true one doesnt have a lot of room for tuning, but the factory leaves sharp edges everywhere. smoothen them out and you have more power. you can also play with the reed boxes on an e tech and put a wall between every leaf, sort of make an enclosed triangle everywhere.
    Why would anybody want a Yamaha when there's an E-Tec?

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    Sam Cullis Mark75H's Avatar
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    Bell or Jennings if you want some science on the length, but I think there is no way to guess what jetting will be needed if it works.
    Since 1925, about 150 different racing outboards have been made.


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    I guess itll be one or two thousands bigger of jets and rich plugs
    Why would anybody want a Yamaha when there's an E-Tec?

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    You'll find quite a lot more intake science in The High-Performance Two-Stroke Engine by Dr. John C. Dixon. isbn 1 84425 045 8

    As it was first published in 2005 it's a generation newer than Jennings & Bell it fits nicely between Jennings, Bell & Blair on the upward mathamatical path.

    A very worthwhile third purchase.

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    Ill look into that, im readig bell right now so thanks a lot!
    Why would anybody want a Yamaha when there's an E-Tec?

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    Team Member ima75man's Avatar
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    had carb stacks made for my 76-75 johnson,didn't see any gain, we went up two jet sizes. they looked cool,just wasn't legal for apba back in the day...didn't help on my 3-2 bbl, 56 inch omc. maybe i didn't spend enough time on set-up......the little blue bottle woke it up..
    out front again

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    Default Velocity stacks - OMC

    Jim Kinsler designed velocity stacks installed on 1BBL OMC's eliminated reversion and smoothed transitions for my 45SS, 49.9 and 56.6's. Jetting did not change.

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