O.S. MAX 55HZ Hyper (L-OS15630) The max 50SX-H Hyper has established an enviable reputation for power, reliability & ease of use. The Max 55HZ Hyper moves that to a whole new level! Designed primarily with the demands of the 3D pilot in mind, the 55HZ Hyper delivers 61 size performance in a 46 size crankcase. That power comes from the extensive experience that OS has gained over many years & working extensively with the worlds top pilots to refine all aspects of the engine without compromise in any area. By using the same mounting layout, you can drop a 55HZ into any model that previously suited the 50SX-H without modification. Just the area around the new carburettor is a little bigger & may require adjustmenst to the cooling shroud. This entirely new engine shares almost nothing with the 50SX-H & has some new features not seen on an engine of this size before. The rear bearing is now designed to resist corrosion, the new 40L carburettor has three adjustments to cater for idle, mid range & full power. Until now, these features were the domain of 61 class engines or bigger. The throttle arm has four leaves so that push pull control is easy from any direction. The heatsink head is bigger for enhanced cooling as well. For the first time, OS is also offering a matching tuned muffler as an option part & has been optimised to extract the maximum performance from the 55HZ Hyper. Part number X-OS72144000. Specification: Weight: 408g (14.39oz) Displacement: 8.93cc (0.55cu.in) Bore: 23mm (0.91in) Stroke: 21.5mm (0.85in) Power Output: 2.1PS @ 17000RPMPractical RPM: 2000
- 20000
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O.S. MAX 55HZ Hyper Engine & Silencer
- Ltd. Ed w/ Pipe (L-OS15637) A special limited edition version of the fabulous Max
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O.S. MAX 55HZ-R Engine (L-OS15650) The latest engine in the 600/50 helicopter class borrows much of its technology from the fabulous Max 91HZ-R, to provide class leading power under the most demanding of 3D manouevres. The latest DRS system (Demand Regulator System) uses a crankcase pressure tap-off to pressurise the fuel tank via a one way valve. The pressurised fuel is then carfully regulated at the carburettor to provide the optimum mixture no matter what demands are placed on it. This is done by using the negative pressure in the carburettor venturi as part of the regulation system. The carburettor itself has three mixture controls for low/mid & high speed settings. Once set for the fuel demands of your model/type of fuel & muffler, there is rarely any need to change those settings again. The main mechanics of the engine itself are the same as the regulat Max 55HZ. Specification: Weight: 429g (15.13oz) Displacement: 8.93cc (0.55cu.in) Bore: 23mm (0.91") Stroke: 21.5mm (0.85") Power Output: 2.1PS @ 17000rpm Practical RPM: 2, 000
- 20, 000
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O.S. MAX 70SZ-H Ring Engine (L-OS17000) Developed directly from the feedback received from top FAI & 3D pilots throughout the world, the MAX 70SZ-H Ring produces copious quantities of power across the rev range without sacrificing its ability to perform precision hovering. Theres a stronger crankcase (with 6-point mounts), 3-needle carburettor & a revised liner/port design to give you the performance you need to beat the world! Particularly suited to the demands of 3D flight. Specification: Weight: 553.5g Displacement: 11.5cc 0.702cu. in Bore: 25.8mm 1.016in. Stroke: 22.0mm Power Output: 2.5/16000 (BHP/RPM) Practical RPM: 2000-18000 ...

O.S. MAX 75AX w/E-4040 Silencer (L-OS17400) The third engine in the new ‘AX’ range of high performance two-stroke engines fills a convenient gap between the existing 61FX & 91FX, yet features the radical new style pioneered with the fabulous 55AX. The new 75AX is supplied complete with the latest ‘P-Box’ design silencer for enhanced noise suppression. By keeping the lower crankcase

Dimensions the same as the 61FX, you can be sure that it will fit in all models designed for a. 61, making a power upgrade very simple. The 75AX features the latest O.S. ringless piston technology with multi-layer cylinder coating & high precision Type 61A carburettor with angled safety needle valve assembly. Specification Weight:578g / 20.39oz w/o silencer Capacity:12.29cc / 0.75 cu.in. Propeller Range:13x 8-10 14x 6-8 Bore:25.8mm / 1.016in Stroke:23.5mm / 0.925in Power Output:2.4PS @15, 000

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O.S. MAX 91HZ-PS Ring (L-OS18620) Designed primarily for the 3D flight & dramatic aerobatic manouevres. Compared to the old Hyper the new 91HZ-PS offers enhanced hovering stability as well as power at high speed to meet the further sophisticated 3D competition manouevres. A new design piston & crankshaft reduces vibration to provide further, stable torque over the entire RPM range. The rectangular heatsink head is completely included in the cooling shroud for better cooling. The black alumite finish with O.S. & 91HZ-PS logo impart a distinctive image. A Thermo insulator is installed on the carburetor mounting spigot & helps shut out engine heat to the carburettor, which in turn ensures a stable fuel/air mixture. The 91HZ-PS is equipped with a new, bigger capacity PD-08 pump & matched 61B-P carburettor plus integral regulator, which assures a consistent fuel supply irrespective of violent changes in model attitude. Combined with O.S. pump system, internal parts improvements same as the 91HZ contribute to stable power output & smoother higher engine performance. Specification: Weight: 635g Displacement: 14.95cc Bore: 27.7mm Stroke: 24.8mm Power Output: 3.5PS @ 15000RPMPractical RPM: 2000
- 16000
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This version of the Max 91HZ series utilises a completely different system for supplying & regulating the the fuel supply to the carburettor & is called DRS (Demand regulator system). Unlike the Max 91HZ-PS, the Max 91HZ-R utilises a pressure bleed from the crankcase to pressurise the main fuel tank. The pressurised fuel feed is then regulated by a newly designed regulator that is well isolated from the heat of the engine through its mounting position. That regulated fuel supply is then feed into the new 61E carburettor. The serious 3D flier now has the choice between a mechanically pressurised fuel system (Max 91HZ-PS) or the tank pressurised system in the Max 91HZ-R. It is purely a matter of personal choice for the pilot. What other manufacturer gives you that level of choice in one engine size? Mechanically, the Max 91HZ-R is identical to the other engines in the Max 91HZ range. Specification Weight: 625g (22.05 oz.) Displacement: 14.95cc (0.912 cu.in.) Bore: 27.7mm (1.091") Stroke: 24.8mm (0.976") Power Output: 3.4 hp @ 15, 000 rpm Practical RPM: 2, 000
- 16, 000 Manufacturer: Ripmax Model: O.S. MAX 91HZ-R Ring (L-OS18640)
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O.S. MAX 95AX w/4040 Silencer (L-OS19120) Designed to replace the 91FX yet retain the same mounting

Dimensions but

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O.S. OMA-3820-1200 Brushless Motor Legendary O.S. quality in a brushless electric motor! This one is intended as a replacement of. 25 class 2 stroke engines using 3 or 4 cell Li-Po packs & will provide strong, linear power. This new range of brushless motors features a unique. O.S. designed cooling system, a strengthened centre body & large ball bearings. The propeller driver has been machined from stainless steel for both strength & durability. Each motor is balanced during manufacture for optimum running & reliability. Supplied with a rear mount & 3.5mm gold connectors as standard accessories.

Specification Weight: 155g Turns: 10 Resistance: 21.4 m Ohms Bearings: 3 Current Range: 30
- 40A ESC Timing Degrees: 20
- 30 Degrees KV RPM: 1200 Max Current: 75A for 10 secs Pole: 14 Power Output: 440W Nominal Voltage: 11.1
- 14.8v (3
- 4S Li-Po) No Load Current: 1.9A Max Efficiency: 85% Shaft dia: 5mm Shaft Length: 11.5mm





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O.S. OMA-3820-1200 Brushless Motor (M-OS51011000) Legendary O.S. quality in a brushless electric motor! The OMA-3820-1200 provides strong, linear power & is intended as a replacement for. 25 two-stroke engines using 3S & 4S Li-Pos. Features include a unique. O.S.
- designed cooling system, a strengthened centre body, large ball bearings & a stainless steel propeller driver for maximum strength & durability. The motor is balanced during manufacture to ensure optimum running & reliability. Supplied with a rear mount & 3.5mm gold connectors as standard accessories. Specification: Diameter: 37.5mm Length: 47.3mm Shaft dia: 5mm Shaft length: 11.5mm Lead wire length: 90mm Male connector: 3.5mm diameter Weight: 155g Poles: 14 Resistance: 21.4m Ohm Current range: 30
- 40A k V: 1200 Li-Po: 3S, 4S Bearings: 3 ESC timing: 20-30 degrees (high) Turns: 10 Max current: 75A / 10 seconds Power output: 440W Nominal voltage: 11.1
- 14.8V No-load current: 1.9A Max. efficiency: 85%


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