Stihl Bike-Handle Trimmer FS 131

  • Purchased from SunSouth on 8/9/2021. Invoice 4030048.
  • SN 526393365
  • 2-year warranty. Also purchased Ultra 6-pack, 1-gallon mix, bought for an additional 2-year warranty for a total of 4 years. Miranda Nitsch, the Salesperson, said she will register the unit and the extended warranty with Stihl.

Webpage here.

Instruction Manual Here.

FS 131 Specifications – Professional Use

DISPLACEMENT 36.3 cc (2.2 cu. in.)
ENGINE POWER 1.4 kW (1.9 bhp)
WEIGHT 5.8 kg (12.8 lbs.) without deflector and cutting attachment.
FUEL CAPACITY 710 cc (24.0 oz.)
CUTTING SWATH 41.91 cm (16.5″)

Youtube – Stihl FS131R 4 Stroke Weed Eater Review | How to Service

Replies to that video include these about it being a 4-stroke but yet requires mixed fuel.

  • David Morse1 month ago @Western Equipment 
    • Stihl went to the 4 stroke design in order to reduce emissions. A two stroke engine cannot keep burned and unburned fuel totally separate so they do not fully combust the fuel. That is why they produce more smoke. With the 4 stroke engine the combustion chamber is emptied of exhaust gasses before a fresh volume of unburned fuel is allowed to enter. This allows for a more complete burning of the fuel.
    • This engine is actually a hybrid because it mixes the two technologies. These engines are made that way so that you can operate them in almost any position, (not upside down). A conventional 4 stroke engine uses oil in the crankcase for lubrication and must be operated in a position that keeps the oil away from the bottom of the piston. With the two stroke crankcase, oil, air, and fuel are drawn in thru the carburator to both fuel the engine and also lubricate the moving parts. This allows the engine to be more flexible as far as operating positions go.

That video does not include how to adjust the valves. For a good video on that go to

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