Thor 250


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THOR 250 have new BLACK crank-case and the well-known features of reduced and compact dimensions match perfectly with the unique weigh/power ration with improved performance.

Polini Thor 250-Thor 250 DS
The main novelties are about reduced consumption, improved maximum power and torque out-put. Thanks to the new cylinder optimized admission transfers, the head has been modified with the optimization of the combustion chamber and squish, while the fuel system has been redesigned with new carburetor setting and new air-intake that improve the gas-petrol flows, making them more stable.

Thanks to this restyling, THOR 250 and THOR 250 DS are equipped with the latest version of the well-known flash starter system, improved in all its parts, with a new ergonomic handle that helps in the ignition phase and increases its safety with a better grip. These technical novelties by the R&D Polini staff make THOR 250 and THOR 250DS new, powerful and reliable engines.

Polini THOR 250 and THOR 250 DS engine feature a liquid cooled system, that grants an extraordinary steady power output and better performance at every rpm.

The die cast light-alloy aluminum cylinder grants a better thermal stability. The liner with Nickel-Siliceous coating improves the piston sliding, its resistance to wear and abrasion. The piston, gravity cast at high silicon content light alloy, reduces thermal expansion and the coupling slack. The piston top design is specific to optimize the compression ratio and to increase the flame propagation speed.

The advanced technology and the great performance of the new THOR 250 and THOR 250 DS give a better feeling when driving making the flight even more performing, dynamic, reactive, beside granting more stability.

THOR 250 and THOR 250 DS are provided with a balancing countershaft; this feature cancels the vibrations and guarantees such a driving comfort never felt during a flight and engines will last much longer.

Polini Motori has focused its attention to the security matter too. THOR 250 and THOR 250 DS are in fact provided with a centrifugal clutch entirely in oil bath, with a mechanical gear with helical teeth. The counter revolving rollers considerably decrease the upsetting torque-steer for a further flight comfort.

THOR 250 and THOR 250DS distinguish themselves for many other advanced solutions, as, for example, the comfortable closed-circuit system for the fuel recovery during transportation and the 12V output for any eventual electrical use.

THOR 250 engine adapts itself to various applications, as two-seat trikes, powered hang gliders, one-seat small three-axis, ULM motor-gliders, ULM and it is available with electric starter, that maintains the manual-starter too.

THOR 250 DS combines the safety of two electronic ignitions, two coils and two spark- plugs with redundant circuits each one independent. These features confirm it as the best engine for the following applications: one-seat three-axis, one-seat trike, light two-seat trikes and many others.


Polini Engine 2 stroke monocylinder
Cooling Liquid cooled
Bore for stroke 72 x 60
Displacement 244 cm3
Power 36 HP
*Max trust 105 Kg with Ø 150 cm propeller
R.P.M. max 8.000
Cylinder Aluminum with Gilnisil coating
Compression ratio 11,5:1
Piston Two chromium plated rings mm 1
Intake Reed valve in the crankcase
Carburetor Polini Ø28 float
Air filter Air box
Ignition Electronic with battery charger possible
Battery charger prearrangement Output power 80 W at 5500 RPM
Spark plug hood 5k Ω resistance
**Fuel type E5 petrol or LL AV GAS-al with 2,5% synthetic oil 100%
*Consumption 2,9 Lh 30 Kg of static trust
Gear reduction unit Helical teeth in oil bath with 2,8 reduction ratio
Starter Flash Starter – (Electric starter -optional)
Clutch Centrifugal in oil bath
Muffler Expansion with oval silencer
Engine weight From 18 Kg (without radiator)
Propeller rotation Clockwise


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