Jetting for Rotax Max EVO Kart

Main jet, needle and spark plug for your Rotax EVO, a mix calculator and a logbook that learns from your engine. Micro, Mini, Junior, Senior and DD2. Proven in racing.

This app recommends main jet, needle position and spark plug for karts with a Rotax Max EVO engine — Micro MAX, Mini MAX, Junior, Senior, DD2 and Supermax — from the weather conditions and your engine setup. The Senior MAX Masters and DD2 Masters categories run the same engine as Senior and DD2, so they are set up in exactly the same way.

The conditions can be pulled from the nearest public weather station using location, or typed in by hand: with no coverage the app works exactly the same.

FOUR SCREENS

• Results: the recommended jet in large type, with the exact calculated value and the two jets it falls between, in green when the choice is clear and in amber when it sits halfway. Also needle position, spark plug, air density, density altitude and relative horsepower. Fine tuning works in steps of 0.5 and tells you what each step achieves.
• Conditions: temperature, pressure, altitude and humidity, each with its own unit. When you pull them from the station you see which one answered, how far away it is and how long ago the reading was taken, with a warning if it is more than 30 minutes old.
• Engine: class, model year, spark plug brand, float height, airbox, oil percentage and oil type, and track type. For Micro MAX and Mini MAX you pick the specification instead of the year, because the MY20 kit can be retrofitted and the year of manufacture does not tell you which engine it is.
• Track logbook: every session with the circuit — picked from a catalogue of 112, with its altitude —, the conditions, what the app recommended against what you actually fitted, how it ran at the bottom, middle and top, the laps and the best time. Exports to CSV.

MORE

• Mix calculator: how much oil that fuel takes, or what ratio you ended up with if you have already poured it. Fuel and oil each have their own unit — litres, millilitres, US or imperial gallons and ounces — and one button leaves the ratio set in the calculation.
• Auto calibration: once the logbook has enough sessions, the app spots whether your engine systematically asks for more or less than the recommendation, and offers to set it as your default fine tuning.
• Share the setup as an image, to send it to the team group.
• Dark mode, system text size, VoiceOver, rotation and iPad.

UNITS

ºC and ºF; metres and feet; mb, hPa, mmHg and inHg; kg/m³, lb/ft³ and lb/gal.

UP TO DATE WITH THE REGULATION

The app follows the Global RMC Technical Regulation, which keeps the Dell'Orto VHSB 34 XS carburettor, the K57 needle, the 4.0 gr floats and the DP267 needle jet. The whole 125 MAX EVO range has been CIK-FIA approved since the 2024 season.

PRIVACY

The app uses no trackers and collects no personal data. If you use location, your coordinates are sent only to look up the nearest weather station.

Available in Catalan, Danish, Dutch, English, French, German, Italian, Norwegian, Portuguese, Russian, Spanish, Swedish and Traditional Chinese.

The app is NOT VALID for Rotax Max engines before 2015. For those engines you should install Jetting Max Kart.