🔧 Rotax 125 MAX Senior EVO (2024+) – Main Jet Size Chart with Tuning Tips

Jetting is one of the most important factors in getting peak performance and reliability from your Rotax MAX engine. The 2024+ EVO engines come with a revised cylinder head and are delivered with a stock #130 main jet. Below is a complete chart to help you tune your kart based on weather, altitude, and performance feedback.

🧠 Jetting Symptoms & Adjustments

When tuning your Rotax engine, your kart will tell you what it needs. Use these symptoms to decide whether to go richer or leaner.

✅ Tips for Trackside Jetting

• Always jet for the worst-case scenario — it’s safer to be slightly rich than too lean.

• Use a temperature gun or your MyChron water temp sensor to monitor optimal temps (~140–150°F).

• Perform plug chops after full-throttle runs to confirm your jetting is in range.

• Keep a full jet case with sizes 124 to 136 to adapt to any weather conditions.