O.S. Speed Spec II

The O.S.SPEED Spec II 21XZ-B has been supported by many top drivers worldwide due to its high performance and achieving excellent results at many major races including podium positions at the last two World Championships.

With the SPEED 21XZ-B, the power you need to win is available at your command. It delivers instant throttle response and powerful torque over the entire rpm range.

The factory-tuned engine further evolves.

New drop-in type outer head with special laser marking contributes to lower CG and better cooling efficiency. Each inner part has been modified for smoother acceleration up to top speed. New lighter piston and connecting rod contribute to better response to driver’s throttle operation. Lighter DLC coated, tungsten weight pressed-in and silicone potted crankshaft reduces friction loss further. Further evolved O.S.SPEED 21XZ-B Spec.II is born to win big races.

Carburetor

21J2(B) carburetor includes 6, 6.5, and 7mm aluminum venturis. Even the smallest 6mm venturi doesn’t change its easy tuning characteristics.

●Specification：3.49cc(0.231cu.in.)

●Bore:16.27mm(0.641in.)

●Stroke:16.8mm(0.661in)

●Practical RPM：4,000r.p.m.〜42,000r.p.m.

●Power：2.65ps(2.61hp)/34,000r.p.m.

●Weight：355g(12.52oz.)

Drake Carb Setting

High Speed Needle 1.3- 1.5

Low Speed Needle .4 – .5

Mid Speed Needle .1