Specification:
- Displacement(c.c. / cu.in.): 14.78 c.c. / .902 cu.in.  
- Bore(mm / in.): 28.0 mm / 1.102 in. 
- Stroke(mm / in.): 24.0 mm / 0.945 in. 
- Practical R.P.M.(R.P.M.): 2,000 ~ 16,000 rpm 
- Output(BHP/RPM): 2.75 BHP / 15,000 RPM 
- Weight(g/oz): 575 g / 20.28 oz 

The PRO series helicopter ring-type engines are equipped with dual ball-bearings, Schnuerle porting, one ring-type piston / cylinder assembly and two-needles automatic mixture control carburetor. The PRO-Heli series are manufactured by automated computer-controlled machinery, resulting in a product that looks and performs better. The PRO-90H provides the smooth hovering and on-demand power and acceleration required by FAI pilots as well "hot dog" and "3-D" aerobatic fliers. Precision air bleed carburetor makes adjustments simple, and efficient mufflers keep things quiet at the field.