OS Engines .21XM VII Outboard Marine Engine

Special Price $539.99 Regular Price $649.99
Out of stock


  • The machined head is aircooled, which insures optimum engine temperature under any conditions
  • The muffler has been extended to generate more torque and power
  • With perfectly matched port timing, exhaust outlets, compression ratio and carb bore, the 21XM VII is designed for competition, right out of the box
  • The 20J carburetor has both highspeed and idle needles
  • A pressure line from the muffler sends a steady flow of lubricants to the lower unit
  • Prop height and angle can be adjusted independently
  • Ball bearings minimize friction and wear for longer life and higher topend speeds
  • The bronze prop shaft assembly offers extreme durability
  • A lightweight aluminum piston is performancematched to a longlasting ABN cylinder sleeve
  • An exceptional value as well as a total competitive package, complete with a #8 glow plug and 42 x 1.2 carbon prop
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OS Engines .21XM VII Outboard Marine Engine

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Product Information

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!

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.


0.211 cu in (3.46 cc)
0.654 in (16.6 mm)
0.630 in (16.0 mm)
Practical rpm
1.28 hp @ 25,000 rpm
24.1 oz (682 g)
Prop Shaft Diameter
3/16 in
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
10-50% nitro boat fuel with at least 18% oil content, starting equipment, fuel tubing
Do not use car or truck fuels; use fuels designed for boat use

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