21XR-B Version II Engine

21XR-B Version II
Long Stroke

Powerful performance for weekend warriors

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.



close-up of carburetor with yellow (7mm) restrictor
The 21J3-I carb comes with two intake restrictors that can be swapped out quickly and easily for fine-tuning to meet track conditions. The yellow (7mm) restrictor (pictured) gives you more bottom end, while the red (8mm) restrictor delivers more top end.
close-up of cylinder head
The blue-anodized aluminum cylinder head delivers superior cooling.
  • Specifications
  • Exploded Views
  • Parts Listing

Stock Number: OSMG2056
Displacement: 0.211 cu in (3.46 cc)
Bore: .641 in (16.27 mm)
Stroke: .661 in (16.8 mm)
Practical RPM: 4,000-40,000
Power Output @ 33,000 rpm: 2.45 ps/2.42 hp
Weight: 13.40 oz (380 g)
Includes: P3 turbo plug