Rotax 125 Senior Max Engine Kit

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  • $3,599.00
  • Regular price $3,999.00
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Rotax Max Senior and Master racing engine. This micro max engine is designed to be a true performance karting engine for all experienced drivers, ages 16+. This engine kit is a complete Senior Max engine kit, with all items necessary to install the engine onto a racing kart aside from a motor mount and exhaust supports, covered below.


The Rotax Senior Max is designed to produce a progressive power band and adaptable power for experienced and sportsman racers alike. Producing approximately 30 hp at peak performance, the Senior Max can propel a full-size kart to approximately 85 mph on large tracks.

The water-cooled, single-piston engine has been engineered over decades of refinement from Rotax BRP Polaris to be easy to run, easy to tune, and easy to maintain.

Peak torque with the Senior Max occurs at about 11,500 RPM, but these engines can routinely rev to 15,000 RPM or more with no issues. Just keep the fuel and oil mixed, water in the radiator, and stay on top of maintenance and the Senior Max hums along!

At approximately 9,000 RPM, the power-valve RAVE system electronically actuates, further improving the timing and performance of the engine at higher RPM levels to keep producing effective power.

The bare engine weighs just about 26.0 lbs, with complete package weighing right at 48 lbs.

At the Senior max level, the engine features the 'senior' exhaust manifold (28mm in size), Max Evo exhaust and radiator.

A battery box, relay harness, start / on / off switch, and all associated hardware to make the engine run (ECU, battery harness charger, etc) is also included in the kit.

The engine also comes sealed with the 2023 cylinder, and with a passport, which is very important in the case that you want to utilize this engine in competitions. Take the engine to your nearest (or favorite) authorized Rotax service center in the USA for inspection, maintenance, and any items that are beyond your purview. This keeps the playing field level with the engine, further enhancing the experience with the Senior Max.

What Else will I Need to Bolt this Engine on a Kart and Run It?

If you are without any other accessories to put this engine on your kart, you will need:

  • 1 Yuasa YT7BS 12v, 9 Amp Kart battery. This comes un-filled, but has a pack to fill the battery with the acid for use.
  • A 5 Degree angled motor mount (we recommend the Odenthal 5-Degree)
  • Rotax Exhaust support clamps (unless your kart already has them)
  • Distilled Water (1 gallon) for the radiator
  • 1 (5) gallon pale of racing fuel (leaded or unleaded depending on your regulations)
  • 1 (liter) bottle of Rotax XPS kart racing oil.