From the experience of Thor 200 engine project, whose production started last year, now Polini presents in preview the new THOR 250. The brand new Polini THOR 250 features a liquid cooling system, that grants an extraordinary steady power output and better performance at every rpm. The die cast light-alloy aluminium 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. The advanced technology and the great performance of the new THOR 250 gives a better feeling when driving making the flight even more performing, dynamic, reactive, beside granting more stability. As its 200cc precursor, the THOR 250 too is provided with a balancing countershaft ; this feature cancels the vibrations and guarantees such a driving comfort never felt during a flight and a better engine lasting. Polini Motori deeply directed its attention to the security matter. The THOR 250 is 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. The hand starter is easier thanks to the flash starter device, which speeds up and simplify the movements. The THOR 250 engine distinguishes itself for many other advanced solutions, as, for example, the comfortable closed circuit system for the fuel recovery during transportation and the 12V way for any eventual electrical use. A version with electric starter is also available as optional. The engine has already confirmed its extraordinary performance features during the tests made on the test benches by the engineers of Polini Motori, in spite of the fact that the project is still in a development stage. The new THOR 250 engine adapts itself to various application types, as two-seat trikes, powered hang gliders, one-seat small three-axis, ULM motor-gliders.