O.S. Engines 21XZ-R VII Competition On-Road Engine w/21M Carburetor


This is the O.S. Engines 21XZ-R VII Competition On-Road Engine. There's a revolution brewing in 1/8 scale racing. The 21XZ-R VII picks up where the original left off, ready to deliver dominating on-road performance with race winning fuel economy. The included 21M carb is unmatched for smooth, linear acceleration. The aggressive timing puts explosive acceleration and top-end speed at your fingertips, while surprising starting ease lets you unleash its race-winning potential right out of the box.


  • Silicone-filled crankshaft is balanced with tungsten weights for optimum balance and minimum vibration.
  • A 1-piece crankcase and 21M slide-valve carb for smoother transitions and higher top-end speeds
  • Redesigned 21M carburetor for improved fuel economy
  • Cylinder liner with 7 scavenger ports and three exhaust ports for maximum combustion and timing efficiency
0.212 cu in (3.49 cc)
Bore: 0.640 in (16.27mm)
Stroke: 0.661 (16.8mm)
Practical rpm: 4,000-45,000
Output: 2.71 hp @ 33,000
Weight: 12.1 oz (343 g)


  • RP7 Turbo glow plug
  • Exhaust seal ring
  • 0.01 & 0.02mm cylinder head gaskets
  • 8.5mm carb venturi
  • Flywheel collet
  • Exhaust, carb and fuel nipple dust caps 

This product was added to our catalog on March 22, 2012.

This item is discontinued and no longer available for purchase. You may want to search our site for a similar item.
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