Carby Delorto 14.12 "...and god said, let there be jets"

Discussion in '2-Stroke Engines' started by Waxxumus, Aug 19, 2015.

  1. Waxxumus

    Waxxumus Member

    Well, in the long process of tuning this carb at about 500 ft above sea level @ about 95-102 F degrees ambient temp.
    I have had to switch back and forth between a 70, a 65, and a 68. The 65 Gives me great power and response, but has quite a hard time starting without choke. It also gets VERY hot. likely above 500.
    The 70 seems less powerful, but the engine never gets above 400F even at wot all day. Actually, the last reading was about 395 right after stopping from a one mile wot up a steep hill. And it starts much easier. Right after the initial revolution.

    So I believe my engine breathes better than some, or has an air leak lolol. But its hard to tell which to choose. Ill go out in the morning and it will be 70F with 10% humidity.
    On the way home its 102F with 80% humidity.

    TEXAS. no good for 2 strokes :( need some consistent weather to base this. Might just run with the 70 so i can keep pooting around at 22~23 mph.
    Ill miss going 26~27 with the 65 though :( was great for short travels. Just seems way too lean.

  2. jaguar

    jaguar Well-Known Member

    this is from my page on the Dellorto:
    "Eventually I figured out that having the perfect size main jet for top rpm running left it a bit too lean at low rpm's and so with a micro drill bit I added another hole at the bottom of the orifice column after making a flat spot there with my rotary tool." That extra hole allowed me to use the small main jet and still get enough gas at low rpm and starting.
  3. Waxxumus

    Waxxumus Member

    So in theory, this extra hole will pull extra gas through the jet while at lower rpms? Or will the smaller hole lose a lot of flow when the throttle opens up allowing the 2 bigger holes above it to enrichen the higher rpms?
  4. jaguar

    jaguar Well-Known Member

    it will enriched running at low rpm. it might also affect the right size needed for top rpm, but probably not.
  5. Fabian

    Fabian Well-Known Member

    In my location of lower south eastern Australia, and using higher octane fuel, equivalent to 93 octane American, my engines have always zoned in on an average jet size of a Delorto No 76, but i have had one engine run well on a No 86, and another engine run well on a No 70, but for the most part they like a jet size around No 76.