21XZ-B Speed

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21XZ-B Speed 21XZ-B Speed

Speed-tuned for championship-caliber performance!

Countless champions, including Mark Pavidis and Atsushi Hara, have trusted O.S. Speed engines to give them a competitive edge. Now, O.S. is proud to continue that winning tradition with the 21XZ-B Speed! A specially designed black-anodized cylinder head improves cooling and reduces weight, while an upgraded, DLC-coated crankshaft improves fuel flow. It all adds up to yet another exceptional, Speed tuned engine from O.S.

  • Unparalleled, speed-tuned power characteristics.
  • Lower fuel consumption – offering 8% longer run times than the standard 21XZ-B.
  • Race-proven 3-port sleeve with special Speed version inner head and porting for smoother acceleration.
  • Tough, DLC-coated crankshaft features a silicone-filled intake passage for improved fuel flow.
  • New 21J2(B) three-needle carburetor includes 6 mm, 6.5 mm and 7 mm restrictors for fine-tuned control.
  • A lowered center of gravity provides steadier vehicle handling.
  • Long stroke allows for superior torque.
  • A black anodized crankcase with ceramic ball bearings helps reduce resistance and increase performance.


Stock number: OSMG2051
Displacement: 0.21 cu in (3.5 cc)
Bore: 0.6 in (16.3 mm)
Stroke: 0.7 in (16.8 mm)
Output: 2.6 hp @ 34,000 rpm
Practical RPM: 4,000-40,000
Weight: 12.5 oz (355 g)
Includes: 21J2(B) carburetor, P3 glow plug, 6.5 mm carb restrictor, exhaust seal and dust cap set
Requires: Glow fuel, muffler, tuned pipe and manifold 

12186 21XZ-B parts listing

Recommended mufflers and accessories:

OSMG2938 72106135 T-2060SC WN Tuned Pipe Set
OSMG2939 72106130 T-2060 WN Tuned Pipe 
OSMG2701 72106430 M2000 Exhaust Manifold 
OSMG2702 72106440 M2000SC Exhaust Manifold


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