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21XM VII .21 Air Cooled Outboard Marine Engine

Item No.
OS Engines - OSMG1720
$725.99
21XM VII .21 Air Cooled Outboard Marine Engine
In Stock
Brand Logo
5 out of 5 Customer Rating

21XM VII .21 Air Cooled Outboard Marine Engine

Item No.
OS Engines - OSMG1720
$725.99
  • Designed expressly for small and medium size outboard boats
  • Installed aluminum tilt transom mounting plate
  • Preassembled outboard unit with flexible propeller
  • Blue anodized aluminum heat sink head
  • 42mm carbon fiber propeller
  • 20J carburetor
Product $725.99
Add Ons
Estimated Total: $725.99

21XM VII .21 Air Cooled Outboard Marine Engine

Item No.
OS Engines - OSMG1720
5 out of 5 Customer Rating
Product $725.99
Add Ons
Estimated Total: $725.99
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Product Details

icon-box
In The Box
  • (1) 21XM Version II Outboard Marine Engine
  • (1) Muffler
  • (1) Mounting Plate
  • (1) #8 Glow Plug
  • (1) Propeller
  • (1) Outboard Unit
  • (1) Steering Arm
  • (1) Product manual
icon-how-to
Needed to Complete
  • Glow Fuel: 10-30% nitromethane content, use 20% for break-in Glow plug igniter and shore equipment
Quick Links
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Engineered to take down the competition!

Take down the competition with the 21XM Version II Outboard Marine engine from O.S.! It retains many of the features found on the successful 21XM, including the 20J carburetor and #8 glow plug. New additions include efficient air cooling, a larger muffler and more!
  • Designed expressly for small and medium-size outboard boats.
  • Cooling the head with air is more reliable than water cooling, and prevents overcooling.
  • The larger muffler boosts engine power for greater speeds.
  • Retains many of the features of the highly successful 21XM.
  • 20J carburetor.
  • Installed aluminum tilt transom mounting plate.
  • Assembled outboard unit with flexible propeller.
  • Blue anodized aluminum heat sink head.
  • 1.7 in. (42 mm) carbon fiber propeller.
  • #8 glow plug.
O.S. 21XM VII Outboard Marine - 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.
O.S. 21XM VII Outboard Marine - muffler
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.

Product Specifications

Product Height 7.2 in (183 mm)
RPM Range 3,000 - 25,000 rpm
Benchmark Prop 42mm carbon fiber propeller included
Displacement 0.21 cu in (3.5 cc)
Bore 0.654 in (16.6 mm)
Crankshaft Type Threaded
Power Type Glow
Plug Type #8 glow plug
Stroke 0.63 in (16 mm)
Muffler Type 2-piece aluminum
Cylinders Single
Product Width 2.5 in (64 mm) at outer mounting hole
Total Weight 24 oz (682 g)
Product Length 8.6 in (219 mm) from flywheel to outboard unit
Crankshaft Threads Reverse