O.S. Engine OSMG2040 21XZ-R Competition On-Road Engine  [OSMG2040]

O.S. Engine 21XZ-R On-Road ABC w/21M
Price:
£265.95
Brand:
O.S. Engine
Model:
OSMG2040
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Product Brief for the O.S. Engine 21XZ-R

The O.S. Engine 21XZ-R On-Road ABC w/21M is intended for competitive 1/8 on-road users who need a dependable, tunable engine. The tungsten-weighted crankshaft improves rotational stability, supporting consistent drive out of corners and manageable midrange torque.

Internal Features and Flow Design

The cylinder liner uses seven scavenger ports alongside three exhaust ports to promote effective scavenging and improved combustion. The updated crankcase and the 21M carburetor are designed to cooperate for smooth throttle transitions, while the light piston and tough con rod are specified for race use.

Engine Output and Application

Displacement is 0.284 cu in (4.65 cc) with a power figure of 3.31 hp at 32,000 rpm and a practical range from 4,000 to 38,000 rpm. The engine weighs 13.1 oz (375 g), offering a compact power package suitable for tuned chassis where weight distribution matters.

Specifications

  • Displacement: 0.284 cu in (4.65 cc)
  • Bore: 0.728 in (18.5 mm)
  • Stroke: 0.681 in (17.3 mm)
  • Practical RPM: 4,000-38,000
  • Power Output: 3.31 hp @ 32,000 rpm
  • Weight: 13.1 oz (375 g)

Drivers seeking a balance of power and tunability for 1/8 on-road competition will appreciate the measured performance and engineering of the O.S. Engine 21XZ-R.

What are good starting carb settings for the 21XZ-R?

Begin with a slightly rich main needle and a moderate idle mixture to protect the engine during break-in. Fine tune on-track for best throttle response and safe operating temperature.

How should I check for wear after heavy use?

Remove and visually inspect the piston and sleeve for scoring, check bearing play at the crank, and listen for irregular noises. Replace any components that show excessive wear to avoid failure.

Is tuning the 21M carburetor difficult?

The 21M is straightforward once you learn needle and throttle response relationships. Make adjustments in small increments and record changes so you can return to previous settings if needed.

What upgrades are recommended for longer life?

Using quality fuel and replacing consumables like bearings and glow plugs at intervals will extend service life. Consider improved cooling heads or tuned exhausts to manage temperatures under race loads.

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