Engine Rotax FR125 Max


History has shown that the sport of karting experiences strong growth when a user-friendly product is introduced, and this was obviously the case with the Yamaha engine. The Rotax FR125 Max is the next step forward, and features:

  • High performance – 28bhp provides reed type performance
  • Reliability And Low Maintenance – The highly detailed instruction manual quotes 50 hours between engine rebuilds
  • Environmentally Friendly – Rotax water cooled design and special muffler is some 5-9db quieter than a Clubman type engine
  • Guaranteed – A new word to Australian karters – 6 month guarantee

Bombardier-Rotax is a world leader in development and production of high performance 2 and 4 stroke engines, and the FR125 Max offers controlled costs, simple setup and tuning, low noise and push button starting. It is the future of performance karting in Australia, and Formula Rotax is already a successful and popular class in Austria, Belgium, England and France.

The FR125 Max was designed to overcome existing engine/class drawbacks, and fill the void that exists in many countries, including Australia, between entry level karting and the high performance formula classes. Because no easy path existed for the progression beyond recreational and competition karting, many newcomers found karting to be less attractive than some other forms of motorsport.

Designed for both hobby and competetition racing, it can be easily mounted on almost any kart chassis using a simple kit, giving any karter the opportunity to experience the power and reliability that this engine is renowned for.

Engines Rotax FR125 Max schematic

Engines Rotax FR125 Max schematic

Engine Designation FR 125 MAX
Description Single cylinder, two-stroke, reed valve engine. Oil-in-fuel lubrication, balance shaft, digital battery ignition, liquid-cooled with integrated water pump, pneumatic controlled Rotax power valve exhaust system, integrated electric starter, dry centrifugal clutch. Right side drive.
Bore/Stroke 54.0mm x 54.5mm
Displacement 124.8cc
Power 21kW max @ 11,500rpm
Torque 21Nm max @ 8,750rpm
Max Allowed RPM Ignition cut-off at 13,800rpm (built-in rev limiter)
Piston Aluminium cast with one rectangular piston ring
Cylinder Light alloy with GILNISIL plating
Ignition Unit DENSO digital battery ignition
Ignition Timing No adjustment possible
Fuel Pump Mikuni diaphragm pump
Fuel Premium unleaded
Carburettor DellOrto VHSB34
Lubrication 1:50 ratio super 2-stroke oil in fuel
Cooling Mixture of water and anti-freeze (suitable for aluminium parts). Circulation by integrated pump. Capacity 22 litres.
Radiator Aluminium radiator, connected direct to engine. Pressure 0.9bar
Clutch Dry centrifugal type, engages at 4,000rpm approx
Direction Of Rotation Clockwise, viewed from pto side
Chain Dimension 219 pitch
Engine Sprockets Standard 13-teeth. 12 and 14 available
Intake Silencer Inlet silencer with integrated, washable air-cleaner
Exhaust System Exhaust pipe with after muffler. Catalytic converter available
Battery 12v battery, electric start
Weight 12kg dry weight, without intake silencer, carburettor, fuel pump, radiator, exhaust system and battery

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