{"product_id":"ums-5-cylinder-125cc-petrol-radial-engine-4-stroke-scale-aircraft-powerplant","title":"UMS 5-Cylinder 125cc Petrol Radial Engine – 4-Stroke Scale Aircraft Powerplant","description":"\u003cp data-start=\"320\" data-end=\"682\"\u003eThe \u003cstrong data-start=\"324\" data-end=\"364\"\u003eUMS 5-125cc 5-Cylinder Radial Engine\u003c\/strong\u003e 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.\u003c\/p\u003e\n\u003cp data-start=\"684\" data-end=\"980\"\u003eReady 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.\u003c\/p\u003e\n\u003cp data-start=\"982\" data-end=\"1354\"\u003eManufactured 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.\u003c\/p\u003e\n\u003cp data-start=\"1356\" data-end=\"1654\"\u003eOptimised for \u003cstrong data-start=\"1370\" data-end=\"1394\"\u003e87–110 octane petrol\u003c\/strong\u003e with a \u003cstrong data-start=\"1402\" data-end=\"1425\"\u003e32:1 petrol\/oil mix\u003c\/strong\u003e, 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.\u003c\/p\u003e\n\u003ch3 data-start=\"1661\" data-end=\"1681\"\u003e\u003cstrong data-start=\"1665\" data-end=\"1681\"\u003eKey Features\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul data-start=\"1682\" data-end=\"2323\"\u003e\n\u003cli data-start=\"1682\" data-end=\"1752\"\u003e\n\u003cp data-start=\"1684\" data-end=\"1752\"\u003eStunning 5-cylinder radial configuration for maximum scale realism\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"1753\" data-end=\"1808\"\u003e\n\u003cp data-start=\"1755\" data-end=\"1808\"\u003e4-stroke petrol engine with smooth, authentic sound\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"1809\" data-end=\"1879\"\u003e\n\u003cp data-start=\"1811\" data-end=\"1879\"\u003eReady-to-run package including exhaust collector ring and ignition\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"1880\" data-end=\"1942\"\u003e\n\u003cp data-start=\"1882\" data-end=\"1942\"\u003eUser-friendly choke and throttle bellcranks for easy setup\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"1943\" data-end=\"1996\"\u003e\n\u003cp data-start=\"1945\" data-end=\"1996\"\u003eCNC-machined aluminium and bar stock construction\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"1997\" data-end=\"2050\"\u003e\n\u003cp data-start=\"1999\" data-end=\"2050\"\u003eAircraft-grade alloy crankcase and cylinder heads\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"2051\" data-end=\"2091\"\u003e\n\u003cp data-start=\"2053\" data-end=\"2091\"\u003eHeavy-duty double-bearing crankshaft\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"2092\" data-end=\"2146\"\u003e\n\u003cp data-start=\"2094\" data-end=\"2146\"\u003eBillet aluminium pistons with hardened steel rings\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"2147\" data-end=\"2208\"\u003e\n\u003cp data-start=\"2149\" data-end=\"2208\"\u003eHard-chromed, lapped cylinder bores for long service life\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"2209\" data-end=\"2270\"\u003e\n\u003cp data-start=\"2211\" data-end=\"2270\"\u003eHardened steel cams for reliability under sustained loads\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"2271\" data-end=\"2323\"\u003e\n\u003cp data-start=\"2273\" data-end=\"2323\"\u003eBurns petrol fuel for efficiency and convenience\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3 data-start=\"2330\" data-end=\"2349\"\u003e\u003cstrong data-start=\"2334\" data-end=\"2349\"\u003ePerfect For\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul data-start=\"2350\" data-end=\"2557\"\u003e\n\u003cli data-start=\"2350\" data-end=\"2404\"\u003e\n\u003cp data-start=\"2352\" data-end=\"2404\"\u003eLarge-scale warbirds and vintage aircraft replicas\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"2405\" data-end=\"2464\"\u003e\n\u003cp data-start=\"2407\" data-end=\"2464\"\u003eScale model aircraft requiring authentic radial engines\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"2465\" data-end=\"2512\"\u003e\n\u003cp data-start=\"2467\" data-end=\"2512\"\u003eSerious hobbyists and professional builders\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"2513\" data-end=\"2557\"\u003e\n\u003cp data-start=\"2515\" data-end=\"2557\"\u003eCustom showcase and competition aircraft\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3 data-start=\"2564\" data-end=\"2587\"\u003e\u003cstrong data-start=\"2568\" data-end=\"2587\"\u003eProduct Summary\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp data-start=\"2588\" data-end=\"2874\"\u003eThe 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.\u003c\/p\u003e\n\u003ch3 data-start=\"2881\" data-end=\"2903\"\u003e\u003cstrong data-start=\"2885\" data-end=\"2903\"\u003eSpecifications\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul data-start=\"2904\" data-end=\"3484\"\u003e\n\u003cli data-start=\"2904\" data-end=\"2940\"\u003e\n\u003cp data-start=\"2906\" data-end=\"2940\"\u003e\u003cstrong data-start=\"2906\" data-end=\"2922\"\u003eEngine Type:\u003c\/strong\u003e 4-Stroke Petrol\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"2941\" data-end=\"2972\"\u003e\n\u003cp data-start=\"2943\" data-end=\"2972\"\u003e\u003cstrong data-start=\"2943\" data-end=\"2957\"\u003eCylinders:\u003c\/strong\u003e 5 (ABC type)\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"2973\" data-end=\"3000\"\u003e\n\u003cp data-start=\"2975\" data-end=\"3000\"\u003e\u003cstrong data-start=\"2975\" data-end=\"2992\"\u003eDisplacement:\u003c\/strong\u003e 125cc\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"3001\" data-end=\"3019\"\u003e\n\u003cp data-start=\"3003\" data-end=\"3019\"\u003e\u003cstrong data-start=\"3003\" data-end=\"3012\"\u003eBore:\u003c\/strong\u003e 31mm\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"3020\" data-end=\"3040\"\u003e\n\u003cp data-start=\"3022\" data-end=\"3040\"\u003e\u003cstrong data-start=\"3022\" data-end=\"3033\"\u003eStroke:\u003c\/strong\u003e 33mm\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"3041\" data-end=\"3073\"\u003e\n\u003cp data-start=\"3043\" data-end=\"3073\"\u003e\u003cstrong data-start=\"3043\" data-end=\"3057\"\u003eRPM Range:\u003c\/strong\u003e 1,000 – 6,000\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"3074\" data-end=\"3123\"\u003e\n\u003cp data-start=\"3076\" data-end=\"3123\"\u003e\u003cstrong data-start=\"3076\" data-end=\"3095\"\u003eApprox. Thrust:\u003c\/strong\u003e 14–15kgf (with 28×8 prop)\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"3124\" data-end=\"3190\"\u003e\n\u003cp data-start=\"3126\" data-end=\"3190\"\u003e\u003cstrong data-start=\"3126\" data-end=\"3153\"\u003eRecommended Propellers:\u003c\/strong\u003e 26×8, 26×10, 27×10, 28×8 (2-blade)\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"3191\" data-end=\"3227\"\u003e\n\u003cp data-start=\"3193\" data-end=\"3227\"\u003e\u003cstrong data-start=\"3193\" data-end=\"3209\"\u003eCarburettor:\u003c\/strong\u003e Walbro \/ WT-621\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"3228\" data-end=\"3273\"\u003e\n\u003cp data-start=\"3230\" data-end=\"3273\"\u003e\u003cstrong data-start=\"3230\" data-end=\"3243\"\u003eIgnition:\u003c\/strong\u003e Electronic (2S LiPo direct)\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"3274\" data-end=\"3298\"\u003e\n\u003cp data-start=\"3276\" data-end=\"3298\"\u003e\u003cstrong data-start=\"3276\" data-end=\"3291\"\u003eSpark Plug:\u003c\/strong\u003e CM-6\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"3299\" data-end=\"3341\"\u003e\n\u003cp data-start=\"3301\" data-end=\"3341\"\u003e\u003cstrong data-start=\"3301\" data-end=\"3313\"\u003eMuffler:\u003c\/strong\u003e Collector ring (included)\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"3342\" data-end=\"3380\"\u003e\n\u003cp data-start=\"3344\" data-end=\"3380\"\u003e\u003cstrong data-start=\"3344\" data-end=\"3353\"\u003eFuel:\u003c\/strong\u003e Petrol with 32:1 oil mix\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"3381\" data-end=\"3422\"\u003e\n\u003cp data-start=\"3383\" data-end=\"3422\"\u003e\u003cstrong data-start=\"3383\" data-end=\"3406\"\u003eDimensions (Ø x L):\u003c\/strong\u003e 265mm x 166mm\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"3423\" data-end=\"3484\"\u003e\n\u003cp data-start=\"3425\" data-end=\"3484\"\u003e\u003cstrong data-start=\"3425\" data-end=\"3436\"\u003eWeight:\u003c\/strong\u003e Approx. 4.6kg including ignition and silencer\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3 data-start=\"3491\" data-end=\"3529\"\u003e\u003cstrong data-start=\"3495\" data-end=\"3529\"\u003eWhy Buy from Probuild Aircraft\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp data-start=\"3530\" data-end=\"3723\"\u003e✅ Official UK stockist – 100% genuine UMS engines\u003cbr data-start=\"3579\" data-end=\"3582\"\u003e✅ Trusted by top international pilots and builders\u003cbr data-start=\"3632\" data-end=\"3635\"\u003e✅ Fast UK shipping and secure packaging\u003cbr data-start=\"3674\" data-end=\"3677\"\u003e✅ Supplying and supporting pilots since 1993\u003c\/p\u003e\n\u003cp data-start=\"3530\" data-end=\"3723\"\u003eManual:\u003c\/p\u003e\n\u003cp data-start=\"3530\" data-end=\"3723\"\u003e\u003ca href=\"https:\/\/ch-ignitions.com\/wp-content\/uploads\/2020\/03\/ums-gas-radial-engine-manual-9-115.pdf\" target=\"_blank\" rel=\"noopener\"\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0934\/7711\/0146\/files\/Screenshot_2026-02-04_115553.png?v=1770206937\" alt=\"\" width=\"233\" height=\"351\"\u003e\u003c\/a\u003e\u003c\/p\u003e","brand":"UMS Engines","offers":[{"title":"Default Title","offer_id":56309750727042,"sku":"UMS5-125","price":2199.0,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0934\/7711\/0146\/files\/UMS-5-125CC-PETROL.jpg?v=1770206514","url":"https:\/\/www.probuild-uk.co.uk\/products\/ums-5-cylinder-125cc-petrol-radial-engine-4-stroke-scale-aircraft-powerplant","provider":"Probuild Aircraft Ltd","version":"1.0","type":"link"}