The second engine in the latest O.S. GT series of petrol engines is designed for the new class of models that are emerging onto the market that are specifically targeted at this size and type of engine. Many of these models are sleek in design, so O.S. has chosen a rear mounted Walbro carburettor with reed valve induction.

The advantage of spark ignition petrol engines over regular glow engines is the optimised ignition timing across the rev range that will not change as load goes on and off.


Like its bigger brother, the GT-55, the GT-33 is a purpose designed model engine and is not based on an industrial unit and just modified. The GT-33 has been optimised in both internal and external shape to provide class leading power and torque in a compact, light package.


Supplied with an E-5030 'Pitts' style silencer as standard, you can be confident that the final installation will be both convenient and unobtrusive yet deliver effective silencing with minimal power loss.