O.S. FS155-A P Ring 70R F6020

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This is an O.S FS155-A Alpha Series 1.55 4-Stroke Pumped Engine. 200-size power in a 120-size package!

How do you get 200-size power from a 120-size engine? O.S. calls it the FS155-a. Since the FS155-a is a pumped 4-stroke, you’ll enjoy 2.6 hp at all times, regardless of tank position, attitude or fuel level. Its novel re-circulation system bathes working parts in constant lubrication, for less friction and wear!


  • Ideal for 120 size scale and sport models and aerobatic models requiring stable power and linear throttle response
  • PD-08 pump and 70R carburetor integrated with regulator ensures stable fuel delivery regardless of model attitude and fuel level
  • F-6020 three piece design muffler with center heatsink
  • Redesigned internal lubricating system eliminates breather tubing from the
  • crankcase
Displacement: 1.548 cu in (25.36cc)
Bore: 1.323" (33.6mm)
Stroke: 1.126" (28.6mm)
Practical RPM: 2,000 - 10,000 RPM
Power Output: 2.6 PS, 2.56 HP @ 10,000 RPM
Engine Weight: 28.40 oz (805g)
Muffler Weight: 3.35oz (95g)
Carburetor Settings:
Needle Valve: 2-1/2 - 3 turns from fully closed
Mixture Control Valve: Factory set, make only small adjustments if
needed, after adjusting needle valve as described in manual, turn
30° to lean idle mixture or 90° counterclockwise to richen mixture
then back again 45° clockwise
Width at Mounting Tabs: 2.6" 67mm)
Crankcase Width below Mounting Tabs: 1.8" (47mm)
Length from Drive Washer to rear of Carburetor: 5" (127.5mm)
Height from Mounting Tab to Pushrod Cover: 4.5" (114mm)
Height from bottom of Crankcase to Pushrod Cover: 5.4" (138.6mm)
Distance between Mounting Hole Centers Same Side: 0.98" (25mm)
Distance between Mounting Hole Centers Opposite Side: 2.3" (58mm)
Distance/front Mounting Hole Center to Drive Washer: 2.5" (64.5mm)
Distance/ Center of Engine to Drive Washer: 3.03" (77mm)
Crankshaft Size: 5/16-24

  • FS155-a P Four Cycle Engine with PD-08 Pump System, 70R Carburetor
  • F-6020 Muffler, Header Pipe, type F Glow Plug, Needle Valve
  • Extension Cable, Instruction Manual
Needed to Complete:
  • Fuel: Glow fuel with 5-20% nitro content and no less than 18% lubricant content
  • Propeller: 16x8-12 or 17x8-12
  • Glow Starter
  • Field equipment

This product was added to our catalog on July 29, 2019