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O.S. SPEED B2104 Off-Road 3.5cc (.21)
O.S.SPEED B2104 Off-Road Racing Engine
O.S.SPEED's off-road racing engine has evolved further. The 4th generation of the B21 series, the "B2104" has improved low-speed response as a result of securing the power to gain an advantage in harsh off-road racing scenes and pursuing a driving feel that steadily demonstrates performance in any situation. Achieves smooth and torqueful performance at medium and low speeds. This has evolved into an off-road engine that perfectly synchronizes with the movement of the fingertips from idling to the highest rpm range. Condensing the know-how of OS SPEED on the whole body, we will continue to make the legend of the off-road racing scene again. It is a long-stroke engine, bore x stroke is 16.27 x 16.80mm. It has quicker response in low range and more torque in middle range with consistent idling.
New Piston/Liner Set
The new piston/liner is conventional 3-port type enabling more torque over the power range.
New DLC Coated Crankshaft
The new crankshaft has DLC coating as we always do for OS SPEED engines. The two tungsten counterweights are embedded in the crankshaft contributing consistent idling and quick rpm down according to throttle move.
New Case Cover Plate
The thrust plate with surface treatment embedded in the cover plate reduces friction against a connecting rod to extend its life.
The boost port and the exhaust port of the crankcase are redesigned for optimum air flow.
The carburetor is trustable 22E type, which we have been using for B2103 Type R.
The cooling head is conventional round-shape type with standard height.
- Displacement: 3.49cc
- Bore: 16.27mm
- Stroke: 16.80mm
- Output: 2.64 hp @ 34.000r.p.m.
- Practical rpm range: 4.000-42.000
- Weight: 352g
- Glow plug T-P3
- Reducer Venturi: 6 & 6.5mm
- Exhaust seal ring
- Dust cap set: 3, 16 & 18mm