For years top drivers worldwide have equipped their rides with O.S. Speed engines because they deliver race-winning performance — and the 21XZ-B Speed Spec II is engineered to take that performance to the next level! Special modifications make this power plant even leaner and meaner, and ready to take you to the winner's circle!

• A lighter crankshaft, with DLC coating, Tungsten weight and silicone-filled intake passage
• Modified piston and con rod that reduces overall weight
• Newly designed outer head with V-shaped fins for lower CG and more efficient cooling
• Dual-adjustable 21J carburetor for smoother acceleration and better fuel mileage
• A 6.5 mm restrictor is installed; 6 mm and 7 mm restrictors are included

Stock Number: OSMG2052

Displacement: 0.213 cu in (3.49 cc)

Bore: 0.641 in (16.27 mm)

Stroke: 0.661 in (16.8 mm)

Practical RPM Range: 4,000-42,000

Output: 2.65 ps @ 34,000 rpm

Weight: 12.52 oz (355 g)

Includes: 21J carburetor, 6 mm and 7 mm carb restrictors, P3 glow plug, exhaust seal and dust cap set

Requires: glow fuel, muffler, tuned pipe and manifold