O.S. Engines 21XR-B Version II Car Engine OSM1AW00

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  • O.S. Engines 21XR-B Version II Car Engine OSM1AW00
  • O.S. Engines 21XR-B Version II Car Engine OSM1AW00
  • O.S. Engines 21XR-B Version II Car Engine OSM1AW00
  • O.S. Engines 21XR-B Version II Car Engine OSM1AW00
  • O.S. Engines 21XR-B Version II Car Engine OSM1AW00
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.16 & UP - CAR
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This is the 21XR-B Version II 1/8 scale Buggy Engine from O.S. Engines. 1/8 scale buggy competition is as fierce as it gets. You want every advantage possible — and it starts with the 21XR-B Version II engine. This version of the 21XR-B power plant has been totally re-designed. It’s even more reliable, and the new 21J3-I carb is easy to tune. The aluminum cooling head ensures steady power even under harsh conditions. And when you're ready to move up to top competition, you can get up to speed with the 21XR-B Version II. This engine is upgradeable with high-performance O.S. Speed Parts, letting you realize your full winning potential. Equip your ride with the 21XR-B Version II, and start owning the podium.


  • Ideal for up and coming 1/8 scale buggy racers and backyard bashers
  • Upgradeable with high-performance O.S. Speed parts
  • Blue anodized aluminum cylinder head
  • Easy to tune 21J3-I slide valve carb with 7mm yellow restrictor for more bottom end performance, and red 8mm restrictor for greater top end speed
  • Natural finish crankcase


Displacement: .213 cu in (3.49cc)
Output: 2.45 PS, 2.42 HP/33,000RPM
Practical RPM Range: 4,000 - 40,000
Bore: 0.641" (16.27mm)
Stroke: 0.661" (16.8mm)
Weight: 13.40oz (380g)
Crankshaft Size: UNF1/4-28
Distance Between Mounting Holes Same Side: 0.83" (21mm)
Distance Between Mounting Holes Opposite Side: 1.45" (37mm)
Height Bottom of Mounting Tabs/Top of Cylinder Head: 3.4" (86.5mm)
Width at Mounting Tabs: 1.8" (45mm)
Width of Crankcase below Mounting Tabs: 1.2" (31.6mm)
Distance from Backplate to Front Bearing: 2.5" (64.5mm)
Distance from Center of Crankshaft to Front Bearing: 1.7" (44mm)
Distance from Center of Crankshaft to Backplate: 0.81" (20.5mm)


  • 21XR-B Version II ABC Buggy Engine with Slide Valve Carb, 7mm & 8mm
  • Restrictors, P3 Turbo Glow Plug, Exhaust Seal Ring, two Dust Caps
  • Instruction Manual


  • 10-30% nitro content fuel, 20% recommended for break-in Exhaust system depending on vehicle.
  • Glow starter, fuel tubing, and track equipment.

Note: Carburetor Settings, carburetor is preset at factory and requires very small adjustments

Needle Valve: Run vehicle with the throttle fully open a few times over long straight course to observe vehicle speed. Close needle valve 15° and repeat run. Gradually close needle valve in subsequent runs to achieve highest speed taking care not to close needle valve too far and overheat engine.

Metering Needle: With the engine running, close throttle and allow engine to idle for about 5 seconds then fully reopen throttle. Turn metering needle clockwise 15-30° to lean mixture if excessive smoke is observed, or counterclockwise 15-30° to richen mixture if engine speeds up momentarily and then cuts out abruptly.

Throttle Stop Screw Adjustment: Turn counterclockwise to reduce throttle opening if engine runs too fast with throttle closed.

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