Checkout this announcement from O.S. Engines.

Precision power for club competition.

When you’re setting out to build your own 1/8 scale buggy racing legend, here’s the perfect place to start — with the 21XR-B engine in your machine.

You get the affordable power you need NOW for backyard bashing. And you have the perfect platform for later adding top-of-the-line 21XZ-B parts, in preparation for serious podium pursuits.

Whether you’re outfitting a new kit or retrofitting an RTR, the 21XR-B delivers enough hassle-free performance to do any weekend warrior proud. Its 22B carb offers simple adjustments. The aluminum cooling head ensures steady power even under harsh conditions.

Eventually high-level competition calls. And when it does, O.S. upgrade parts are available to answer. Just tune up your 21XR-B…and watch your legend grow.

• Ideal for up-and-coming 1/8 scale buggy racers.
• Engineered to deliver maximum performance — with minimal effort.
• Easy-to-adjust 22B carburetor.
• Proven O.S. cooling technology for steady power under severe conditions.
• Upgrade easily for high-level action — accepts 21 XZ-B parts.

From top to bottom, the 21XR-B has been thoroughly engineered to power your 1/8 scale buggies to victory!

A blue-anodized aluminum cylinder head keeps the engine cool under harsh conditions.

The 22B carburetor allows easy tuning.

SPECIFICATIONS
Stock number: OSMG2055
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: 4,000-40,000
Output: 2.4 hp @ 33,000 rpm
Weight: 13.4 oz (380 g)
Includes: P3 Turbo Plug
Requires: Glow fuel, tuned pipe