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O.S. - OSMG1982 OSM18645 18645 531028021419 4531028021419
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O.S. 91HZ-R 3D Speed Black w/Powerboost Pipe
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O.S. 91HZ-R 3D Speed Black w/Powerboost Pipe
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Tech Notes
This is the O.S. Engines 91 HZ-R 3D Speed Helicopter Engine in Black
with the 91 PowerBoost Tuned Pipe.

****** Because of the competition nature of this engine,******
******it is NOT covered by the O.S. 2 Year Warranty.******


Designed for all-out 3D competition
DRS (Demand Regulator System) ensures a steady fuel supply for 3D
165 exhaust timing for optimal horsepower and stable hovering
Newly designed combustion chamber shaped to match the big bore
carburetor and advanced exhaust cylinder timing
61G Big Bore twin needle carburetor is designed to develope stable
horsepower at 70-80% throttle which is widely used in 3D flight
PowerBoost pipe is constructed of polished natural finish aluminum
and was developed exclusively for flights with 90 size helicopters


91 HZ-R 3D Speed Helicopter Engine, with PowerBoost Pipe, Exhaust
Tube and Mounting Hardware, #8 Glowplug, Check Valve, 0.2mm Head
Gasket and Instruction Manual


Fuel: 10%-30% nitromethane with at least 18% lubricant. Lubricants
may be either castor or synthetic oil or castor/synthetic blend.
Field Equipment: glow starter, fuel bulb, fuel can filter, fuel pump
hexagonal starting shaft (depending on brand of helicopter)
electric starter, battery and fuel tubing


Displacement: 0.91cu in (14.9cc)
Bore: 1.091" (27.7mm)
Stroke: 0.976" (24.8mm)
Power Output: 3.6hp / 15,500 RPM
Practical RPM Range: 2,000 - 16,000
Weight (w/o Muffler): 21.27oz (603g)
Crankshaft Size: 5/16-24

Carburetor Adjustments-
High Speed Needle Valve: Turn approximately 30 (3-4 clicks) during
initial adjustments, then approximately 15 (1-2 clicks) when
making final adjustments
Medium Speed Needle Valve: Turn approximately 30 (3-4 clicks) at a
Idle Mixture Control Screw: Turn approximately 5 at a time, turn
left to enrich idle mixture and right to lean mixture
Height from crankcase bottom to top of cylinder head: 3.9" (100mm)
Height/bottom of mounting tab to top of cylinder head: 3.1" (79mm)
Distance between mounting holes same side: 0.98" (25mm)
Distance between mounting holes opposite side: 2" (52mm)
Distance between muffler screw holes: 1.6" (42mm)
Distance/bottom of mounting tab to muffler screw holes: 1.8" (42.8mm)
Distance throttle lever to center of engine: 1.6" (42mm)
Length from front bearing to center of engine: 2.2" (56.4mm)
Length from front bearing to backplate: 3.3" (83.8mm)
Length from backplate to end of crankshaft: 4.6" (118mm)
Length from backplate to center of engine: 1.1" (27.4mm)
Width of crankcase below mounting tabs: 1.7" (43mm)
Width between mounting tabs: 2.4" (61mm)

Length: 12.3" (313mm)
Diameter: 2.0" (50mm) at engine attachment point
Exhaust Outlet Diameter: 0.20" (5mm)
Weight: 7.9oz (225g)

jxs 04/08/11

– If you need more information, use these O.S. resources –
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.Speed .91HZ-R 3D Competition Heli Engine w/PowerBoost Pipe. FEATURES: REQUIRES: 10%-30% nitro fuel w/at least 18% lubricant content, glow starter & field equipment

Accessories for the O.S. 91HZ-R 3D Speed Black w/Powerboost Pipe

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