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Calcimator

Carburetor Jet Sizing

Calculate carburetor jet size corrections for altitude and temperature.

Inputs

ft
°F
%

Results

Corrected Jet Size

130

Jet Change7.2%
Correction Factor0.928
Density Altitude9,056 ft
Needle Clip Position3
How to Use This Calculator
  1. Enter Base Main Jet Size, Riding Altitude, and Air Temperature.
  2. Set Humidity.
  3. Review the Corrected Jet Size result.
  4. Use Jet Change (%) and Correction Factor to inform your decision.

How the result changes with Base Main Jet Size

Base Main Jet SizeCorrected Jet Size
7065
120111
180167
230213

What each input means

Base Main Jet Size
Stock main jet size number for sea-level tuning.
Riding Altitude
Elevation above sea level in feet.
Air Temperature
Ambient air temperature in Fahrenheit.
Humidity
Relative humidity percentage.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Base Main Jet Size = 140, Riding Altitude = 5000, Air Temperature = 75, Humidity = 30 = 4 input(s) provided
  2. Calculate Corrected Jet Size
    Corrected Jet Size
    130 = 130
  3. Calculate Jet Change
    Jet Change
    7.2 = 7.2
  4. Calculate Correction Factor
    Correction Factor
    0.928 = 0.928

Engine last updated . Checked against 3 independently-derived tests — how we verify calculators.

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