New motors from O.S.

Ripmax have news of two O.S. motors that have just arrived in the UK. First up is the O.S. FSa-56 four-stroke. Sporting the new blue head design, this is the first engine in a completely new series of advanced four-stroke motors known as the Alpha series. This new ’54 has increased capacity compared to the old FS-52 Surpass so giving more power and torque.

The new carb’ provides more throttle control across the entire RPM range and has a constant velocity tube to prevent fuel from spitting out when accelerating under load.
There are new features like incorporating the breather/oil recirculation system into the crankcase to dispense with external nipples and drain tubes.


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  • Name – O.S. FSa-56
  • Displacement – 9.32cc/0.569
  • Bore – 24mm/0.945 in
  • Stroke – 20.6mm/0.811 in
  • Weight – 16.26oz with silencer
  • RRP – £184.99

    The new O.S.Max 75AX is the fourth engine in the new AX range of two-stroke engines and fills the gap between the 61FX and 91FX. The lower crankcase dimensions are the same as the 61AX, so it will fit in all models designed for a ‘sixty’ size motor. It is supplied with the new and, from this writers own experience, very effective P-Box silencer.


  • Name – O.S. 75AX
  • Displacement – 12.29cc/0.75
  • Bore 25.8mm/1.02 in
  • Stroke – 23.5mm / 0.93 in
  • Output – 2.4ps/15000rpm
  • RPM range – 2000 – 16000rpm
  • Weight – 578g/20.4oz
  • RRP – £134.99

    See the Ripmax website for more information.

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