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Thread: What carburetor for modified clone build?

  1. #1

    What carburetor for modified clone build?

    Currently in the middle of building a modified clone, starting out with a 2.815 block, dyno cam cheater crank, .020 longer arc rod, arc fixed timing flywheel, 356 cam. Head has been re worked with 28.5 intake valve and seat and 25mm exhaust, shaved .075 off the head, and am also using the champion 1:1 rocker arm set up. With this set up what would be a good carb to go with, was thinking about trying the gx390 but would like input on trying a slide carb, anyone recommend a certain one? No rules or restrictions on the carb either.

  2. #2
    4 Cycle Advanced User
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    What kind of track do u run? And what fuel are u going to use?

  3. #3
    Track is a real short, big bank dirt track not sure of overall length. Running methanol

  4. #4
    4 Cycle Advanced User
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    We use a flat side 28mm mikuni. Works very well...

  5. #5
    Thanks Jncyall

  6. #6
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    Mike Clements Racing sells a real nice blueprinted 28mm flatslide carb that is blueprinted and set up for your engine when you buy one, and his are the best out there when it comes to flatslide carbs in my opinion. He includes extra jets for the carb if you ask. Check out his website, they are around $175 ready to go. I know you can buy a 28mm flatslide carb on eBay or wherever for about half that price or less, but they do not work nearly as well out of the box and they need alot more work to convert them to alky

  7. #7
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    Running alky I would run a young engines 390 or a tilly carb from Dustin Stephenson

  8. #8
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    run the barry young carb

  9. #9
    Is there a certain linkage you have to get with these carbs for the throttle cable?

  10. #10
    4 Cycle Advanced User
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    The 390 should use pretty standard stuff.
    A mikuni uses a end like a motorcycle a slim barrel shape.
    Tilly needs a bracket and cable .
    Airtight Garage Est 1982
    Waller Racing
    Phantom Chassis

  11. #11
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    The 390 carb needs a longer throttle rod from the top plate to the carb, and it pulls the throttle open instead pushing it open like on stock clone carbs. You will need a gx200 to gx390 intake adapter, the 390 carb, and 390 air filter adapter, you can make your own throttle rod out of coat hanger, to make a longer one. Pretty simple to do

  12. #12
    I think there's a better choice of cam for the track and head choice..jmo

  13. #13
    Thanks for all the input guys, I know the 356 cam is way to much for this track, was given to me for free so was just gonna use it

  14. #14
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    .356 is a great short track cam, I have one in a stroker animal that I run in RWYB and it kills the big blocks and MX engines on the bullrings and short tracks here. You need a good flowing, well built head and a carburetor to match for that cam to work best. I suggest using a billet cam so you can advance or retard cam timing easily to suit your needs, and an adjustable flywheel so you can also tweak ignition timing easily as well, but the adjustable flywheel is not a must.

  15. #15
    Thanks W5R, just curious what's the benefit of advancing and retarding the cam timing?

  16. #16
    4 Cycle Advanced User
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    each degree moves the power band up or down approximately 100 rpm.
    Airtight Garage Est 1982
    Waller Racing
    Phantom Chassis

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