Fox + Son Jetmax
Rotax jetting calculator
Only for iPhone
Free · In‑App Purchases · Designed for iPhone. Not verified for macOS.
iPhone
Precision jetting made easy — This app helps you calculate jetting for Rotax engines based on weather and altitude. 7-day FREE trial. Try it now!
Precision jetting made easy — This app helps you calculate jetting for Rotax engines based on weather and altitude.
Now every Rotax racer has access to the same jetting Fox + Son has used to power our engines to countless Rotax National wins and Grand Finals tickets. After many months of development and testing, we have successfully brought the same jetting algorithms we use on our dyno to a quick, easy-to-use app. We have also included all of our popular Rotax tuning tips that are found on our website, along with a handy interactive gear chart for your convenience. As we do with our website, we will continually update the app as we discover new tuning information. Anytime a new cylinder or part is introduced, all of the testing we do at the shop will flow directly to Jetmax.
Jetmax will also calculate the relative horsepower for that atmospheric condition. The relative horsepower percentage is helpful information to have when selecting your gear ratio. In certain situations you can benefit from increasing your gear ratio when HP is low & decreasing your gear ratio when HP is high.
Whether you're competing at the track or fine-tuning your kart for practice, Jetmax gives you accurate, reliable recommendations so you can focus on performance.
Features:
- Jetting calculator for Rotax engines
- Calculates relative horsepower
- Includes an interactive gearing chart
Engineered by racers, for racers — Fox + Son Jetmax App delivers the tools you need to stay competitive on race day.
*You must have a valid subscription in order to use this app.
-Added "US Spec Micro" engine type
-Optimized jetting for longer tracks
The developer, Trophy Inc., indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Linked to You
The following data may be collected but it is not linked to your identity:
- Purchases
- Location
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Trophy Inc.
- Size
- 16.3 MB
- Category
- Sports
- Compatibility
Requires iOS 15.1 or later.
- iPhone
Requires iOS 15.1 or later. - iPod touch
Requires iOS 15.1 or later. - Mac
Requires macOS 12.0 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 1.0 or later.
- iPhone
- Languages
- English
- Age Rating
4+
- 4+
- In-App Purchases
Yes
- Premium Yearly $7.99
- Copyright
- © 2025 Trophy Inc.