• New



Specs ---------------------------
Stroke volume: 3.49 cc / 0.213 cu.in.
Bore: 16.27mm / 0.641 in.
Stroke: 16.80 mm / 0.661 in.
Output: 2.68 ps / 2.64 hp / 34,000 rpm
Practical rotation speed: 4,000-42,000 rpm
Weight: 352 g / 12.42 oz.
Standard accessory
T plug T-P3 1 piece

Reducer φ6Ⅱ, φ6.5Ⅱ
Exhaust seal ring 1 piece
OS SPEED Dust cap set 12-30 ・ φ3, φ16, φ18 1 each



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OSSPEED's off-road racing engine has evolved even 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. We will continue to create the legend of the off-road racing scene again by condensing OSSPEED's know-how on the whole body.

Product features

  • 2bn03000.jpg

    Inheriting the long stroke of the previous model B2103, which has won numerous major races. The newly designed cylinder / piston uses 3 ports. Achieve torqueful performance by reviewing the timing change and air-fuel mixture flow.

  • shaft.jpg

    The newly designed crankshaft has undergone OSSPEED's traditional DLC processing to review the timing and optimize the weight balance, so two tungsten weights are installed, resulting in improved idling and slow drop.

  • plate.jpg

    By adopting a thrust plate with special treatment on the cover plate, wear due to interference between the connecting rod and the cover plate during rotation is reduced and the engine life is improved.

  • case.jpg

    The crankcase has been brushed up based on the B2103 to improve performance.

  • cab.jpg

    The carburetor adopts a highly reliable double adjust type 22E

  • hed.jpg

    The outer head adopts a standard round type with a new laser design

5 Items

Specific References