Rotax Jetting App

The Rotax MAX Jetting App was first released in 2016 specifically designed for the Rotax 125 MAX evo engines. There is a new update available of the App providing you the perfect main jet set-up in any ambient conditions, assuring high end racing no matter the weather.




The Rotax MAX Jetting App calculates the recommended main jet size based on the ambient conditions and the engine type. The engine type can be chosen in the app from the Rotax 125 MAX Micro up to the DD2 categories. Ambient data can be defined either automatically via GPS or entered manually. The GPS is triggering the weather data from the next available weather station but as Android and iOS have access to different weather stations, there could be a slight difference comparing the datas.


The App assumes the entered air pressure to be at sea level (relative air pressure), therefore if using your own barometer please make sure that it is calibrated to the current altitude.


The calculation is based on fuel ROZ 95. Using fuel with higher ROZ might require a different main jet than recommended.

The Rotax Max Jetting App does not release the user from his own responsibility in choosing the correct main jet size.



  Needle clip position


The position of the needle clip will influence the air/fuel mixture mainly in the range from 1/4 to 3/4 throttle opening.

The standard clip position is 3.

A lower clip position (2 or 1) will result in a leaner air/fuel mixture.

A higher clip position (4 or 5) will result in a richer air/fuel mixture.



  Air adjustment screw


The air adjustment screw mainly influences the air/fuel mixture in the range from 0 to 1/4 throttle opening.

The standard position is 2 turns out from closed.

More turns out will result in a leaner air/fuel mixture. Less turns out

will result in a richer air/fuel mixture.




The calculation can be done either automatically using GPS and a functioning internet connection or manually by entering the ambient parameters.




Click on Use GPS position for weather data, select the desired engine type from the scroll menu and start the calculation tabbing the Calculate button.




Enter all ambient parameters, select the desired engine type from the scroll menu and start the calculation tabbing the Calculate button.

Important: Since the calculation is based on the "relative air pressure" (air pressure at 0m above sea level), your own barometer must be calibrated to the current altitude before you can actually use the value. Online weather services provide this value by default.


To toggle between Celsius and Fahrenheit, press °C/°F and to choose between meters and feet press m/ft next to the entry of the value.


To start a new calculation, click Reset.


The Rotax Jetting App is available for Android and Apple



Rotax Jetting App Android Rotax Jetting App iOS



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