Rotax Junior Max Engine

  • Sale
  • Regular price $3,822.50
Shipping calculated at checkout.

Rotax Max Junior racing engine. This Junior max engine is designed to be a more advanced engine for racers, aged 12-16. This engine kit is a complete Junior Max engine kit, with all items necessary to install the engine onto a racing kart aside from a motor mount and exhaust supports, outlined below.


The Rotax Junior Max is designed to produce a progressive power band and adaptable power for more advanced junior racers. Producing approximately 23 hp at peak performance, the Junior Max can propel a full-size kart to approximately 75-80 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 Junior Max occurs at about 8,500 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 Junior Max hums along!

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

At the Junior max level, the engine features the 'Junior' exhaust manifold (28mm in size), full-size Rotax Evo exhaust, and radiator. The Junior does not have the power valve, however.

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, 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 Junior 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.