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

O.S. Engine 21XZ-R On-Road ABC w/21M
Price:
CAD$497.53
Brand:
O.S. Engine
Model:
OSMG2040
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Track Overview for the O.S. Engine 21XZ-R

The O.S. Engine 21XZ-R On-Road ABC w/21M is built for serious 1/8 scale on-road racers seeking a predictable, high-performance powerplant. Careful engineering and balance work together so the tungsten-weighted crankshaft delivers steady torque through low and mid ranges, helping drivers maintain driveability around technical layouts.

Engine Detail and Porting Benefits

The 21XZ-R features a specially machined cylinder liner with seven scavenger ports and three exhaust ports to improve scavenging and combustion efficiency. The updated crankcase and the 21M carburetor are matched to provide a smooth power curve, while the lightweight piston and robust con rod are specified for endurance under race conditions.

Power Numbers and Usability

With a displacement of 0.284 cubic inches (4.65 cc), the 21XZ-R produces 3.31 horsepower at 32,000 rpm and runs usefully from about 4,000 up to 38,000 rpm. Weighing 13.1 ounces (375 grams), the engine balances output and mass to suit tuned on-road chassis where both response and reliability matter.

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)

Racers who prioritise consistent torque and precise throttle response will find the O.S. Engine 21XZ-R a reliable option for 1/8 on-road competition, offering a strong blend of power and durability.

What tuning changes help the 21XZ-R breathe best?

Lean and rich needle adjustments on the 21M carburetor combined with correct clunk position will refine midrange response. Small carburetor trims and fuel choice will affect peak rpm and idle stability.

Which fuel mix works well with this engine?

A high-quality nitro fuel around 15 to 25 percent, with a balanced oil content for your bearings, gives a good starting point. Adjust the nitro level based on track altitude and engine break-in results.

How often should I service rotating parts?

Inspect the crankshaft assembly and con rod after every few race weekends. Regularly check for play, and replace bearings or the con rod if wear or scoring appears to avoid failures under load.

Can this engine be tuned for different track layouts?

Yes, the 21XZ-R responds well to carburetor and clutch tuning. Shorter gearing and richer midrange tuning suit tight technical tracks while taller gearing and leaner top-end settings fit faster circuits.

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