Carby CNS High Performance Carb

Discussion in '2-Stroke Engines' started by bradfords, Jul 21, 2016.

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  1. bradfords

    bradfords Guest

    I purchased this carb. It is running rich. I know the stock jet is .72mm. I live in michigan and was wondering what size jet I should by to run leaner. Thanks

  2. Frankenstein

    Frankenstein Well-Known Member

    Leaner is smaller, try 70, even try 65, some eBay sellers have sets that include 65-70, you can use those to lean and rich the carb out during different parts of the year
  3. Steve Best

    Steve Best Well-Known Member

    Mine was quite rich. Overall, I like the CNS, works well. My jet was not marked for size and I leaned it with the fine wire method. I recommend getting a selection of jets if you can buy them that way. You will want to jet for extreme temperature changes.

  4. jaguar

    jaguar Well-Known Member

    Steve, did you change the needle position to also be leaner?
  5. Steve Best

    Steve Best Well-Known Member

    No I didn't Jag, not yet anyway. I installed it, started and worked fine, ran it.
    Plug was black and engine started with no choke ever, sign of too rich. Power was OK.
    Dropped the float level 2mm, power and top speed improved. Another 2mm, improved again. Plug just showing colour.
    Float raised to stock, fine wire put in jet (no jets available) bike ran great. Plug runs dark tan.
    Dropped float 2mm, no power improvement, Plug still dark tan, slight bog in mid-throttle.
    That is where I am now. Putting float back up tonight (to stay on safe side) and see if bog is still there.

    Dropping the float is like a half jet change (75 to 72.5) but it often creates a bog trying to pick up the fuel.
    The wire in the jet is a dangerous trick. Easy to over lean it or have jetting change as the wire moves. Not recommended.