The UMS 5-125cc 5-Cylinder Radial Engine is a premium petrol-powered 4-stroke engine designed to deliver exceptional realism, smooth performance, and long-term reliability for large-scale model aircraft. With its authentic radial layout and superb machining quality, it perfectly replicates the look, sound, and operation of classic vintage aircraft engines.

Ready to run straight out of the box, this engine is supplied complete with an exhaust collector ring, electronic ignition system, spark plugs, carburettor, and engine mount. User-friendly choke and throttle bellcranks make installation and operation straightforward, even in complex scale cowls.

Manufactured using CNC-machined aluminium and aircraft-grade alloys, the UMS 5-125 is built to exacting standards. Internally, it features a heavy-duty double-bearing crankshaft, billet aluminium pistons with hardened steel rings, hard-chromed and lapped cylinder bores, and hardened steel cams ensuring smooth running, excellent power delivery, and outstanding longevity.

Optimised for 87–110 octane petrol with a 32:1 petrol/oil mix, this radial engine delivers powerful thrust with dependable operation. Whether powering a large warbird, vintage replica, or custom scale project, the UMS 5-125 provides unmatched mechanical beauty, performance, and durability.

Key Features

• Stunning 5-cylinder radial configuration for maximum scale realism

• 4-stroke petrol engine with smooth, authentic sound

• Ready-to-run package including exhaust collector ring and ignition

• User-friendly choke and throttle bellcranks for easy setup

• CNC-machined aluminium and bar stock construction

• Aircraft-grade alloy crankcase and cylinder heads

• Heavy-duty double-bearing crankshaft

• Billet aluminium pistons with hardened steel rings

• Hard-chromed, lapped cylinder bores for long service life

• Hardened steel cams for reliability under sustained loads

• Burns petrol fuel for efficiency and convenience

Perfect For

• Large-scale warbirds and vintage aircraft replicas

• Scale model aircraft requiring authentic radial engines

• Serious hobbyists and professional builders

• Custom showcase and competition aircraft

Product Summary

The UMS 5-125cc radial engine combines breathtaking scale realism with modern engineering excellence. With its ready-to-run design, robust construction, and proven reliability, it is the ideal centrepiece for high-end scale aircraft projects demanding both performance and authenticity.

Specifications

• Engine Type: 4-Stroke Petrol

• Cylinders: 5 (ABC type)

• Displacement: 125cc

• Bore: 31mm

• Stroke: 33mm

• RPM Range: 1,000 – 6,000

• Approx. Thrust: 14–15kgf (with 28×8 prop)

• Recommended Propellers: 26×8, 26×10, 27×10, 28×8 (2-blade)

• Carburettor: Walbro / WT-621

• Ignition: Electronic (2S LiPo direct)

• Spark Plug: CM-6

• Muffler: Collector ring (included)

• Fuel: Petrol with 32:1 oil mix

• Dimensions (Ø x L): 265mm x 166mm

• Weight: Approx. 4.6kg including ignition and silencer

Why Buy from Probuild Aircraft

✅ Official UK stockist – 100% genuine UMS engines
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