AirPro Jetting App Guide for Rotax Jetting | Prisma Electronics

AirPro Jetting is the app developed by Prisma Electronics to help drivers, mechanics and engine tuners interpret the data measured by the AirPro Densimeter and obtain a practical indication of the jet changes to apply according to atmospheric conditions.

AirPro APP Jetting and Prisma Electronics Densimeter

Optimizing Carburetion in Two-Stroke Engines with the AirPro Air Densimeter

Table of contents

• What AirPro Jetting does
• Why air density affects carburation
• Before you start: how to use the AirPro Densimeter correctly
• Main screen of AirPro Jetting
• The recommended jet screen
• Exporting sessions
• AirPro Jetting settings
• Best practices for using AirPro Jetting at the track
• AirPro APP Frequently Asked Questions

What AirPro Jetting does

In two-stroke engines, carburation can change significantly throughout the day depending on atmospheric conditions. Temperature, atmospheric pressure, humidity and air density influence engine behaviour and may require changes to the carburettor main jet.

AirPro Jetting uses a wireless connection to read data from your AirPro Densimeter: temperature, atmospheric pressure, humidity, relative altitude and air density. This data is used together with the selected Rotax engine model to recommend the most suitable carburettor main jet size for the measured conditions.

The app also allows you to save each measurement as a session, add notes, associate it with the track name and export the data in PDF or CSV format.

What you need to use AirPro Jetting

• An iPhone or iPad running iOS 26.2 or later.
• The AirPro Densimeter by Prisma Electronics.

AirPro Densimeter for Optimizing Combustion in Two-Stroke and Four-Stroke Engines.

Why air density affects carburation

The amount of oxygen available in the air changes according to temperature, atmospheric pressure, humidity and altitude. When air density changes, the air/fuel ratio required for correct combustion also changes.

For this reason, during a race weekend or a test day, carburation may require adjustments even from one session to the next. AirPro Jetting is designed to help you turn the atmospheric data measured by the AirPro Densimeter into a practical reference for choosing the carburettor main jet.

AirPro Jetting is a technical reference, not an absolute value

AirPro Jetting performs a calculation based on the atmospheric data measured by the AirPro Densimeter and the selected Rotax engine model.

However, ideal carburation also depends on variables that cannot be automatically measured by the app, such as:

• the driver’s driving style;
• the grip available on track during that session;
• the vehicle setup, which may change even after a few laps;
• the fuel being used;
• the condition of the engine and carburettor;
• the experience of the mechanic or technician supporting the driver.

For this reason, the app cannot take all these variables into account and must be used as a reference between sessions during a race weekend or free practice day. Its purpose is to help you understand how atmospheric conditions are changing air density and, as a result, affecting carburation. Correct carburation must always be checked and managed by experienced professionals.

The app is particularly useful for comparing sessions during a race weekend or test day, understanding how atmospheric conditions are changing and evaluating how these variations influence carburation.

Correct carburation must always be checked and managed by experienced personnel.

Before you start: how to use the AirPro Densimeter correctly

To obtain accurate data, it is essential to use the AirPro Densimeter correctly. The instrument must be left in ambient air so that it can thermally stabilise with the surrounding environment.

Holding the densimeter in your hand, keeping it in your pocket, placing it near heat sources or exposing it to direct sunlight may distort the measurements and lead to values that do not accurately represent the real air conditions.

The ideal condition is to place the AirPro Densimeter in a shaded position, exposed to natural air circulation, away from hot surfaces, running engines or direct heat sources.

Main screen of AirPro Jetting

The main screen of AirPro Jetting includes all the fields needed to download data from the densimeter, select the engine, set any corrections and calculate the recommended jet.

Main screen of the AirPro Jetting app with data from the AirPro Densimeter.

Select your Engine

From this section, you can select your Rotax engine model. Engine selection is required because the jet calculation is adapted to the selected configuration.

Track Location

The location function allows you to associate sessions with the circuit where you are working. This helps you organise your measurement history and quickly find the saved sessions for each track.

Data from the AirPro Densimeter

Once the connection with the densimeter has been established, the app fields are automatically filled with the values from the last session stored in the instrument.

The data used by the app includes temperature, atmospheric pressure, humidity, relative altitude and air density.

Carburation Adjustment

Carburation Adjustment allows you to adapt the app calculation to your real track experience.

If, after a test, you find that the ideal jet is slightly richer or leaner than the one suggested by the app, you can correct the calculation behaviour using this parameter.

The setting remains stored and is considered in the following calculations, helping you build a reference over time that is more aligned with your engine, the fuel used, the driver’s style and your working method.

This function is particularly useful because ideal carburation can be influenced by factors that cannot be automatically measured by the app, such as track grip, driving style, kart setup or specific engine characteristics.

Your notes

In this field, you can enter all notes related to the session. For example, you can record a specific configuration, the driver’s feedback, the fuel used, track conditions or any other information that may help you interpret the data more clearly in the future.

Notes are saved together with the session and become part of your working history.

Calculate Jet

After connecting the app to the densimeter, downloading the data and selecting the correct Rotax engine, press Calculate Jet to obtain the recommended jet.

Connect to Densimeter and Download Data

These commands allow you to connect the app to the AirPro Densimeter and download the data from the last session stored in the instrument.

To proceed, enable the wireless connection on the densimeter, connect it to the app and download the data from the last session.

By pressing Calculate Jet, the app processes the AirPro Densimeter data and displays the recommended jet.

How to download the session to the app

1. Enable the wireless connection on the densimeter.
2. Open AirPro Jetting on your iPhone or iPad.
3. Download the data from the last session.
4. Select the Rotax engine model being used.
5. Locate yourself on the circuit using the map.
6. Add notes, if required.
7. Check the Carburation Adjustment value.
8. Press Calculate Jet.
9. Analyse the recommended jet and compare it with previous sessions to understand whether there have been any variations.

The recommended jet screen

Once you press Calculate Jet, the app opens a window showing the data from the AirPro Densimeter and the recommended jet.

The same screen also shows the Carburation Adjustment value, so you can understand whether the result has been modified according to the correction set by the user on the main screen.

Result screen with the measured data and the jet recommended by the app.

Saving sessions

By pressing the Save Session button, you can save the current session on your device.

Stored sessions are organised using filters such as Favorites, Today and This Week. You can also search sessions by circuit, making it easier to compare different tests on the same track.

Saved sessions can be filtered and reviewed by time period or track.

Favorite sessions

When reviewing saved sessions, you can mark the most important ones as favorites.

For example, if you find a session where carburation was particularly effective, you can press the star icon in the top right corner and save it among your favorite sessions. This allows you to use it as a reference for comparing future atmospheric conditions and carburation choices.

The most significant sessions can be saved as favorites for faster comparison.

Exporting sessions

Each session can be exported in PDF or CSV format.

The PDF is useful for quickly sharing a readable report with drivers, mechanics or technicians. The CSV file can be opened with software such as Excel or other analysis tools, allowing deeper processing of the collected data.

Example of a PDF export from an AirPro Jetting session.

AirPro Jetting settings

AirPro Jetting allows you to change the units of measurement used in the app.

By pressing the gear icon in the top right corner of the main screen, you can access the settings menu and set the units of measurement for:

• temperature in °C/°F
• relative altitude in m/ft
• air density in kg/m3 or lb/ft3

Settings menu for the units of measurement in the AirPro Jetting app.

Fast Download

A very useful function of AirPro Jetting is Fast Download.

This function allows you to set the AirPro Densimeter you are using as the paired device for quick download. In this way, to download sessions from the densimeter to the app, you only need to enable the wireless connection on the instrument and bring it close to the iOS device.

Sessions are downloaded automatically, making the workflow faster during a day at the track.

You can also store two or more instruments on one device. This allows the team to centralise data downloads on a single device, keeping all sessions from different drivers and/or engines stored in one place.

The Fast Download function allows sessions to be quickly downloaded from the AirPro Densimeter to the app.

Renaming the device

From the settings menu, you can rename the paired device. This function is especially useful when using multiple instruments or when several drivers and mechanics work in the same pit box.

Assigning a clear name to the densimeter helps you quickly identify the correct device and avoid confusion during download operations.

Best practices for using AirPro Jetting at the track

As mentioned above, it is essential to use the AirPro Densimeter correctly. To get the most from AirPro Jetting, the app should be used as part of a consistent and repeatable working method.

• Always let the AirPro Densimeter stabilise before downloading the data.
• Avoid taking measurements with the instrument exposed to direct sunlight or close to heat sources.
• Save each session with clear notes and track references.
• Use favorite sessions as a reference when you find an effective carburation setup.
• Compare air density variations from one session to another.
• Use the Carburation Adjustment value only after verifying the real engine behaviour on track.
• Always have carburation checked by experienced personnel.

Conclusion

AirPro Jetting is designed to help drivers, mechanics and engine tuners work with a more structured method during a race weekend or test day.

By correctly measuring air conditions with the AirPro Densimeter and saving each session in the app, you can build a useful history to understand how carburation changes as air density varies.

The result is a more precise, repeatable and professional approach to choosing the carburettor main jet.

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