.21XM VII Outboard Marine Engine

21XM VII Outboard Marine Engine

The next generation in .21 outboard marine performance!

Leave it to the engineers at O.S. to concoct a sure-fire recipe for marine racing success! First, they started with the 21XM, O.S.' exceptional outboard engine and winner of 11 championships in a 4-year span. They then upgraded the cylinder head and muffler. The result: the 21XM VII, an air-cooled powerhouse that's even faster than the original!

Ran the new version II this morning - pushed my VS1 tunnel hull faster than I've ever seen it go. - Jerry Dunlap
Cylinder Head
Cooling the cylinder head with air is more reliable than water cooling, and prevents overcooling. It also adds the benefits of simpler construction and less maintenance.
While being larger than the muffler used with the .21XM, the VII's muffler is still just as easy to tune, still detachable for easier maintenance, and more responsive than a tuned pipe.
  • Specifications
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  • Parts Listing
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Stock Number: OSMG1720
Displacement: 0.211 cu in (3.46 cc)
Bore: 0.654 in (16.6 mm)
Stroke: 0.630 in (16.0 mm)
Practical rpm: 3,000-25,000
Output: 1.28 hp @ 25,000 rpm
Weight: 24.1 oz (682 g)
Prop Shaft Diameter: 3/16 in
Includes: mount, outdrive unit, E-2050-2 removable muffler, starter cone, #20J carb, #8 glow plug, steering bracket, throttle link assembly & 42 x 1.2 carbon prop
Requires: 10-50% nitro boat fuel with at least 18% oil content, starting equipment, fuel tubing
NOTE: Do not use car or truck fuels; use fuels designed for boat use

Primary Accessories

Stock Number Mfr Number Product Description Quantity Needed
 GPMQ4131  GPMQ4131  Great Planes Silicone Fuel Tubing Standard 3' 1
 HCAP0200  HCAP0200  Hobbico 12 Volt Charger U/L Listed 1
 HCAP0800  HCAP0800  Hobbico TorqMaster LC 12V 7Amp Battery 1
 HCAP3200  HCAP3200  Hobbico TorqMaster 90 Deluxe 12V 1
 SULP1826  S626  Sullivan Starter Belt Boats/Heli 1

Field Equipment

Stock Number Mfr Number Product Description Quantity Needed
 DTXP0310  DTXP0310  Duratrax Ultimate Glo-Starter C 1
 OSMR2976  71521000  O.S. Long Socket Wrench With Plug Grip 1

Optional Accessories

Stock Number Mfr Number Product Description Quantity Needed
 HCAP3001  HCAP3001  Hobbico After Run Engine Oil 2 Fl Oz 1
 HCAP3205  HCAP3205  Hobbico Panel Ready TorqMaster 90 1
 ODOP3030  ODOP3030  O'Donnell 30% Boat Gallon 1
 ODOP3130  ODOP3130  O'Donnell 30% Boat Fuel Quart 1
 OSMG5872  72403050  O.S. Super Can Filter Large 1