Now it's easy to setup a Rotax MAX FR125 kart engine.

KartMAX Jetting Software is a tool designed for use with the Rotax MAX FR125 Sr kart engine.

The purpose of this tool is to recommend a jet, needle position and spark reference, taking in consideration the weather conditions on the racetrack.


With this utility, engine-tuning headaches ended. Just enter weather conditions and KartMAX proposes theoretical values for the best engine performance.

In addition, the fine-tuning allows correcting small differences with some engines.


To design this software, data has been taken for more than seven years at racetracks all over the world in order to develop the best possible algorithm.

This data acquisition has allowed designing a very accurate but really easy to handle software, so it can be used by beginners and expert drivers. Also data and comments for users from all over the world have been taken into consideration.

KartMAX only supports MAX Senior engines.

MicroMax, MiniMax, Junior and DD2 aren't supported in this version.

KartMAX is designed be used in with Dell'Orto Carb standard settings:

8.5 or 12.5 Venturi inserts
K98 needle
3.6 floats - #60 idle jet - #60 inner idle jet
5.2 floats - #30 idle jet - #30 inner idle jet
2:100 oil/fuel ratio

If you have any problem using this software, please, contact us. We are always trying to improve it.

Weather data

KartMAX new version allows to obtain meteorological data through geolocation if you have internet access, which avoids having to carry a weather station to the racetrack.


Location data are completely anonymous, shared with the World Weather Online server to get weather data and recorded on our servers for statistical purposes. This information is anonymous and is not used for any other purpose.

Location rights of the App can be modified at any time in Settings -> Privacy -> Location

In the event that the server data were not precise enough, we recommend using a first-class weather station. If weather station incorporates altitude/pressure correction, please introduce altitude "0" in KartMAX.

Carb-Ice Warning

KartMAX now incorporates a warning sign of ice formation in the carburetor.

Carb-Ice is caused as the carburettor vaporizes fuel. It cools the intake air. If the air temperature drops below dew point, moisture in the air condenses into water droplets. Ice forms near the carb slide and venturi when water touch carb walls that are cold.

In severe cases (high humidity, low temp), ice can block jets, resulting in an unexplained progressive lost of engine power even at temperatures above 25ºC (77ºK). The effect is temporary, so it can not be diagnosed in boxes.

KartMAX includes a warning sign with three levels of risk:

Low risk
Medium risk
High risk

To reduce the risk of carb-ice is recommended to use a quality fuel, avoiding any water contamination, and take the air filter clean and oiled.

For more information, WikiPedia.org

Lap chronograph

Record all your circuits, sessions, drivers and times.

Professional chronograph. Get times up to four drivers at the same time.


Get best times for circuits, sessions, personal times, lap differences, etc.

Share your best results over Twitter or Facebook

Colors meaning:

1'35"93 Best Circuit time

1'41"12 Best Session time

1'53"47 Personal best time in this session


Customer reviews

Spain Muy buena!!! star star star star star

Fantástica aplicación, te ayuda a la hora de carburar un motor para karting en condiciones!!

United States No engine option. star star star

Do not have option for Sr. Jr. Mini. Micro

Italy Da migliorare star star star star

La carburazione consigliata, non da le migliori prestazioni (di solito la carburazione ottimale e' molto più ''magra'' di quella consigliata) e poi mancano dati importanti come la regolazione della vite dell'aria.

Spain Esta muy bien star star star

Pero haría falta saber para que combinación de boyas, chicles de bajas y aguja, esta calculada esta aplicación, ya que depende la combinación que lleves hace falta un chicle mas grande o pequeño.

United States Program works as listed star star star star

Used the app this weekend for the first time and it worked good

United States Great experience star star star star star

The customer service from this company was outstanding. Very knowledgable about Karting and has created a wonderful app that can assist in setting up the jetting for the Rotax Max Jr. karts. I am waiting anxiously for the Rotax Micro Max app to come out soon. Thanks for the app, the service, and your true sense of caring about helping the customer.

United Kindom Great experience star star star star star

Started using this and got lap record and won races.

Other translations

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Weather services