The OS Speed B2105 RC engine has evolved into the fifth generation of the B21 series. It is designed to secure power that gives an advantage in harsh off-road racing scenes and pursues a driving feel that steadily demonstrates performance in any situation. 
By re-designing the cylinder liner and crankshaft, we have achieved smooth and linear power delivery. Furthermore, the effect of a lighter outer head successfully improves drivability in any situation.
Displacement: 3.49 cc / 0.213cu.in.
Bore: 16.27mm / 0.641 in.
Stroke: 16.80mm / 0.661 in.
Output: 2.68 ps / 2.64 hp / 34,000 r.p.m.
Practical rpm range: 4,000-42,000 r.p.m.
Engine Weight: 348g / 12.28 oz.