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O.S. - OSMG1307 OSM37010 37010 531028020672 4531028020672
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O.S. FR7-420 Sirius7 7-Cylinder Engine
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O.S. FR7-420 Sirius7 7-Cylinder Engine
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On-line Videos: Video 1 (YOUTUBE)
Instruction Manuals: Manual 1 (3.7 MB)
Tower Catalog Page: 175

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Tech Notes
This is the O.S. Sirius7 FR7-420 7-Cylinder 4-Stroke Engine.


Main internal parts such as the crankshaft, cam holder and reduction
gear are all plated to resist corrosion
V-shaped individual valve covers for vintage scale appearance
Impeller system distributes air-fuel mixture equally to each cylinder
ensuring high performance and smooth idle
Padded and lockable aluminum silver colored storage case
Two year limited warranty through Hobby Services beginning at date of


O.S. Sirius7 FR7-420 7-Cylinder Sirius 4-Stroke Engine, seven type F
glow plugs, valve adjusting kit, radial mount & hardware kit,
needle valve extension cable, drain plug, carburetor insert, decal,
glow plug cable set, instruction manual and aluminum case


Fuel: Aircraft blend 5-10% nitro content with 8-10% lubricant
content (it is suggested to dilute commercially available 15%
nitromethane and 18% lubricant fuel with methanol half and half to
make a 7.5% nitro and 9% lubricant fuel)
Propeller: 22x10-12, 23x8-12, 24x8-12, 26x8


Displacement: 0.6071cu in x 7 (9.95cc x 7)
Bore: 0.944" (24.0mm)
Stroke: 0.866" (22.0mm)
Practical RPM: 1,500 - 7,000
Weight: 111.7 oz (3,167g)
Crankshaft Size: UNF3/8-24
Distance from Backplate to Drive Washer: 6.2" (158.5mm)
Outer Edge of Backplate to Pushrod Covers: 4.8" (122mm)
Outer Diameter: 9" (230mm)
Carburetor Settings:
Needle valve, 2-1/2 turns open from closed position
Throttle Valve, approximately 1/4 turn open from closed position,
then start engine and follow break-in instructions on pages 19-25
in manual

jxs 06/24/10

– If you need more information, use these O.S. resources –
Click Here: Manufacturer's Product Web Page
Email: enginesupport@hobbico.com
Web Site: http://www.osengines.com/
Phone: 217-398-8970
  Postal Address:

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Accessories Needed
This is the O.S. FR7-420 7-Cylinder Sirius 4-Stroke Engine. FEATURES: Individual valve covers for vintage scale appearance, plated main internal parts to resist corrosion REQUIRES: Fuel, propeller, field equipment

Accessories for the O.S. FR7-420 Sirius7 7-Cylinder Engine

Primary Accessories     Optional Accessories
  Special Stock Number Product Description Parts Saver Eligible Tower's
Low Price
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 LXACPN O.S. Plug Terminal Sirius 7
Qty Discount Available
6.79   In Stock
Subtotal for this Group of Accessories: 6.79  

Primary Accessories     Optional Accessories

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