Cooling head:The cooling heads of the ROMA.21 engines are made lighter by making aditional holes in the cooling fins. This reduces the overall mass of the engine.
Rear ball bearing:The outer diameter of 25.80 mm has been adopted in order to avoid ring distorsions and to increase fatigue resistance.
Carburetor:This carburettor is made from plastic and have a sliding throttle valve. (reverse type)
Sleeve: The sleeve has 7 transfer ports and an exhaust with booster ports. The special shape and positioning of the ports, covered by a patent, improve the internal fluid-dynamics to obtain the maximum possible performance.
Crankshaft:The Turbo SG crankshaft is made from high quality steel.
Gasket: The inner shape of the gasket has a new shape, and with that more material. Together with a change in material these gaskets are more resistant to high temperatures.
Glowplug: The glowplug of engine is a Turbo type glowplug. Turbo glowplugs have a different shape than Standard glowplugs and therefor are not interchange able with engines that are using Standard glowplugs!