Well here it is.... the engine that everybody has been waiting for, Ideal for all hard pilots, easy to tune, heaps of power..A real must

The Ys 50St Engine Features the Patented YS regulated fuel system for positive flow during all types of flight conditions

Bore : 22mm
Stroke : 21.5mm
Displacement : 8.17cc
Weight:  398g
Practical Rpm:  2000-20000rpm