Descrizione O.S. SPEED R21 EURO SPEC II This engine inherits the smooth and easy-to-use feeling of the predecessor, O.S. SPEED R21 EURO Spec., And by reviewing the counterbalance of the crankshaft, low and mid end power delivery has been improved. The smooth RPM drop and idling stability are also improved, and the optimum performance is demonstrated even in the long and harsh race scene. Succeeding the previous model, every part has been improved including the outer head with new design to improve the cooling performance. Features: 1/8 on-road racing engine New cooling-head design. New combustion chamber with o-ring New Crankshaft. New sleeve design with extra cooling-ports on the lower exhaust side. Specifications Content: 3.49 cc Bore: 16.08mm Stroke: 17.20mm HP: 2.8 ps / 2.76 hp at 33000 r.p.m. Practical range: 4000-45000 r.p.m. Weight: 340g