O.S. Speed B2105 Combo Set .21 Nitro Engine with TB02 Pipe

O.S. SPEED B2105 Combo Set

O.S. part #1EK01

The O.S. Speed B2105 Combo Set is a competition-focused .21 nitro engine and tuned pipe package built for serious 1/8-scale off-road buggy racing. As the fifth generation of the proven B21 series, the B2105 is designed to deliver smooth drivability, strong usable power, and consistent performance in demanding off-road race conditions.

The B2105 features a redesigned cylinder liner and crankshaft to create a smoother, more linear powerband. This helps improve throttle control, drivability, and confidence on changing track surfaces. A lighter outer cooling head improves overall response, while race-focused internal components support durability during high-RPM competition use.

This 3.5cc off-road racing engine operates within a practical 4,000–42,000 RPM range and includes performance features such as ceramic bearings, a DLC-coated crankshaft, and a double-seal front bearing for improved stability and long-term reliability.

The combo set includes the O.S. TB02 tuned pipe, giving racers a matched O.S. Speed engine and exhaust package for competitive 1/8 nitro buggy racing.

Key features

 -Genuine O.S. Speed B2105 Combo Set

 -.21 / 3.5cc nitro race engine

 -Built for 1/8-scale off-road buggy racing

 -Includes O.S. TB02 tuned pipe

 -Fifth-generation B21 series engine

 -Redesigned cylinder liner and crankshaft

 -Smooth, linear power delivery

 -Ceramic bearings

 -DLC-coated crankshaft

 -Double-seal front bearing

 -Practical RPM range: 4,000–42,000 RPM

Spec

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 RPM

Practical rpm range: 4,000-42,000 RPM

Engine Weight: 348g / 12.28 oz.

Standard accessories

Glow plug T-P3Reducer φ6Ⅱ、φ6.5ⅡExhaust seal ringDust cap set 12-30(φ3、φ16、φ18)

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