Rotax Max 125 Junior 2026 Evo

The Rotax 125 Junior Max EVO is the latest in a long line of models since Rotax built its first kart engine over 40 years ago.

Rotax has always placed full focus on an exciting and affordable driving experience combined with excellent reliability.

Rotax is in fact the only manufacturer in the world that offers a factory warranty on its racing engines – proof of the high quality that these hand-built engines from Austria can deliver.

Technology:

With the Rotax 125 Junior Max Evo, you get everything you could ask for in a modern kart engine:

• Reliable electric start with long battery life
• Official apps that help you tune your engine perfectly
• Engine management (ignition and more) is handled entirely by the engine's ECU (Electronic Control Unit), giving you a perfect result every time.
• All parts are manufactured in-house at Rotax's state-of-the-art factory in Austria
• The engines have a very long service interval – up to 50 hours of running time, which is significantly longer than any comparable competitor.

Engine components:

Crankcase: The crankcase is manufactured from die-cast aluminium

At over 15 bar of pressure, molten aluminium is pressed into a mould. The high pressure guarantees a strong, solid casting with a perfect result.

After casting, the crankcase is machined by computer-controlled mills with extremely high precision, after which the entire crankcase is powder-coated with a durable surface finish.

Piston and cylinder: The cylinders are also cast in aluminium before being CNC-machined to achieve as even a result as possible.

The cylinder bore is Nicasil-treated, Nicasil is one of the hardest surface treatments available and has nearly unlimited durability.

Another major benefit of Nicasil is that you only need a 2% oil mix, which is good for the environment and good for your wallet.

The piston is made from forged aluminium and, after machining, coated with a Teflon surface; this increases service life and gives you the best possible performance through reduced friction.

Cooling: All Rotax engines have a closed water-cooling system that runs without external water pumps; the high flow rate and large aluminium radiator guarantee the correct operating temperature (50-60°C) even under hard driving.

Ignition: The ignition is digital and fully electronically controlled via the engine's computer box; with the help of a sensor at the crankshaft, you are guaranteed correct ignition every time. You also get a variable ignition curve that adapts to the engine RPM, all for the best possible performance.

Clutch: Via the clutch, made from hardened steel, the engine power is transferred to the drive chain and then to the rear axle.

The clutch normally lasts several years and is maintenance-free; your engine sprocket is mounted on the clutch drum, and by replacing this you can easily re-gear the engine in under 1 minute's work.

Carburettor & fuel: A powerful vacuum-driven fuel pump feeds the fuel to a 34mm Dellorto carburettor developed specifically for the Rotax engine.

The carburettor can be adjusted by changing the jet and adjusting the throttle needle; information on which jetting you should use is available via the Rotax App, which, based on your location, gives you optimal jetting based on temperature and air pressure.

Mounted on the carburettor is the engine's air intake; air is guided into the carburettor through a foam filter – guaranteed clean and with the correct flow.

Thanks to the airbox's smart design, there are no problems at all running the engine in heavy rain.

Specifications:

• Cylinder capacity: 125cc
• Power: 23hp at 8,500 rpm
• Torque: 19Nm at 8,500rpm
• Weight: 11.8kg (engine only) 23kg (complete engine package)
• Ignition: Electronic ignition
• Electrical system: 12V 7Ah
• Cooling: Water-cooled

You get everything you need to run and use your Rotax engine. This is included in the engine package:

• Complete engine
• Radiator and radiator hoses
• Exhaust pipe, silencer and exhaust mounts
• Fuel pump, carburettor and fuel filter
• Throttle cable
• Intake silencer / airbox with mount
• Complete electrical system (spark plug, ignition coil, wiring harness, starter motor, battery, control panel, ignition sensor)
• Frame mount for battery and electrical system
• Instruction manual and engine logbook