AD2

The O.S. Speed B21AD2 engine has several updates from champion Adam Drake.  It’s an excellent choice for both buggy and truck racing as it provides a linear power band, exceptional fuel mileage and tons of overall power.

Featuring a unique semi-long stroke configuration, this engine also boasts a DLC crankshaft with larger double tungsten counterweights and a unique cylinder design that’s exclusive to the Drake edition engines.  These changes will provide smoother low end power and more overall torque.

The B21AD2 is based off the B21AD and features a new crankshaft, cooling head, head button with an o-ring to reduce vibration and keep dirt out, new carburetor ball, and different size venturi. The B21AD2 combo includes the 2100SC pipe and 75mm manifold.  The 2090SC with 85mm manifold is also a nice option for the B21AD2.

Features

  • Adam Drake’s unique engine specs not used on any other O.S. Speed engine.
  • Great for buggy and truck racing.
  • Redesigned cylinder liner with optimized porting.
  •  DLC crankshaft with larger double tungsten counterweight.
  • Semi-long stroke configuration.
  • 6.5 and 7.0 mm carburetor reducers.
  • Ceramic rear bearing.
  • 21J carburetor.

Specifications

  • Displacement: 0.213 cu in (3.49cc)
  • Bore: 0.646″ (16.4mm)
  • Stroke: 0.652″ (16.55mm)
  • Practical RPM: 4,000-42,000 RPM
  • Output: 2.65PS 34,000 RPM, 2.61HP @ 34,000RPM
  • Weight: 12.45oz (353g)

Drake Carb Settings

  • High Speed Needle: 1.35mm – 1.5mm in from flush.
  • Low Speed Needle: 0.45mm – 0.6mm in from flush.
  • Mid Speed Needle: flush to 0.15mm in from flush.