The new Polini Thor 202 stands out for its extraordinary weight reduction. Compared to the Thor 200 HF it is actually 1.6 kg lighter although with a liquid cooling system and is more powerful than 4 horsepower, with an optimized torque curve especially at low revs, which guarantees lower fuel consumption and greater flight comfort. in addition to exceptional thermal stability.
Great attention has been paid to the aesthetic and aerodynamic aspect, designing and building a completely new airbox with a modern and small size design. The same goes for the cylinder, totally redesigned and highly performing to ensure maximum performance.
An exclusive, reliable, long-lasting product with exciting performance to allow a longevity of the engine and a TBO (time between overhaul) of 400 hours.
The heart of the engine is the thermal unit specially designed and built with the latest generation devices. The actual displacement stands at 205 cubic centimeters with a bore of 66mm and a stroke of 60mm. The cylinder is equipped with 5 inlet ports to ensure precise performance and a fast delivery capable of offering over 90 kg of static thrust with a 130 cm propeller.
The 2-stroke engines are in the Polini DNA. Thanks to the experience gained by the company over years of studies and design, it has been possible to create an unprecedented exhaust system.
It is characterized by a totally new expansion concept, which makes it more compact and lighter. Thanks to a long test work it was possible to find the perfect combination between expansion and gas flows: the result is a muffler that ensures stable and progressive delivery at all speeds, with fixing to the engine guaranteed by the suspension system that ensures freedom of movement by dampening all vibrations.
A further improvement is given by the revision of the joint, positioned one third of the muffler itself, and composed of a ball joint that allows complete freedom of movement, further guaranteeing the duration of the exhaust.
The new Polini THOR 202 is equipped with the Orto carburettor.
The 28MM Dell’Orto VHST carburetor has allowed to refine the carburetion setting, ensuring smooth performance.
The main features are the very low consumption due to a very effective Venturi system: consumption is 2.4 Lt per hour at 5000 RPM, which corresponds to about 30 kg of static thrust, average level flight value with a 130 propeller. cm (data collected on standard settings at sea level and which can be improved in competition).
The particular design makes it much less sensitive to environmental changes in atmospheric pressure, humidity and air pressure, ensuring greater stability to changes in latitude / longitude and altitude and minimizing any setting interventions. This carburetor can also be equipped with the Polini starter control to be able to operate the choke even when harnessed.
Thanks to all these advantages, combined with various setting possibilities, the Orto carburetor will be able to perfectly meet the needs of all pilots, thanks to the very high precision, fluidity and power delivery, combined with very low fuel consumption. .
The new air filter is the result of an in-depth fluid-dynamic study which aims to optimize the speed of the air inside it to ensure the ideal pressure to feed the carburetor at every rotation speed. By reproducing an S-shaped circuit that stabilizes turbulence, the new filter allows a linear, smooth and constant delivery. Completely openable and inspectable, inside there is a support frame for the new 30 PPI (pores per inch) open cell polyurethane foam filter mat: this support frame is designed to have a fastening able to prevent over time the mat to move or collapse on itself. Furthermore, the filter box can be opened in two halves with only two screws, making it easy to replace during routine maintenance.
The new filter boasts a modern design and is more compact than previous versions: this means that it is located closer to the engine by 45 mm: this decreases the aerodynamic drag during flight.
Cooling system and water pump
Cooling is guaranteed by a compact 16-element radiator measuring just 300 x 170 mm and has been designed so that an expansion tank is not necessary.
The cap is equipped with a 1.4 bar valve that allows the system to self-regulate the expansion of the liquid inside it without burdening the other components. The exclusion of the vessel and its components contributes to aerodynamics and the reduction of the overall weight.
With a view to greater attention to design, pre-shaped blue silicone tubes have been chosen which, in addition to making the engine colorful and attractive, guarantee a longer life of the tubes over time.
valve The engine is equipped with a reed valve with direct entry into the crankcase. The reed valve pack, expressly designed by the Polini R&D department, is designed to maximize performance. This result is obtained thanks to the use of 6 carbon fiber blades with calibrated elasticity to react uniformly to all rotation speeds.
casing The Thor 202 casings are made of die-cast aluminum with a high silicon content: thanks to this alloy and to the production process controlled during all phases (starting from the foundry, passing through the painting and then to the mechanical processing on sophisticated CNC machines), stable and long-lasting mechanical performance combined with low weight is achieved.
The crankcase design has been optimized to be essential and reinforced in the points of greatest stress, extending to a full 400 hours of TBO.
The choice of the best steels and heat treatments, combined with perfect centering, eliminates parasitic vibrations due to imbalances which over time could lead to premature wear or failures.
Thanks to the use of numerical control machines and latest generation measuring instruments, the sizing is maintained within predetermined tolerances with maximum perfection. The whole is completed by high quality bearings positioned on the connecting rod and in the crankcase.
Countershaft, reduction gear and clutch
In the front crankcase half there are the housing of the centrifugal clutch system, the mechanical reduction and the balancing countershaft, all in an oil bath.
The centrifugal clutch allows the propeller to remain immobile when the engine is at idle speed and to maximize safety for the pilot in the pre-flight phases.
The reduction is mechanical with helical teeth: this system reverses the direction of rotation of the propeller with respect to the rotation of the motor shaft, clearly damping the overturning torque.
The balancing shaft dampens the vibration deriving from the imbalance generated by the oscillation of the piston which, passing from the lower dead center to the upper one, moves its mass at each rotational cycle of the engine, thus ensuring maximum flight comfort.
Polini THOR 202 is equipped with an inductive electronic ignition: more compact and lighter than the version present in the Thor 200 HF, it reduces the overall overhang of the engine by 16 mm, making the engine more compact.
The Thor 202 is equipped with the most updated version of the renowned flash starter, a system that guarantees immediate and simplified starting of the engine.
In the latest version, critical points have been reinforced and centering has been improved, improving operation and ensuring longer life. In addition, an ergonomic handle allows a safer and more stable grip during the ignition phase.
Polini Motori has decided to keep the same fixing system on the whole range of Thor crash bars. A choice that benefits both manufacturers and drivers.
Manufacturers can produce a frame that can accommodate the entire range, significantly reducing both manufacturing costs and lead times.
Riders can change Thor models without having to replace or modify the frame.
Like the whole Thor range, the new 202 is sold complete with all its parts, completely assembled and ready to be installed on the frame with extreme simplicity.