How to Tune a Stihl FS80R

The Stihl FS80R operates with an adjustable three-speed setting carburetor. These screws regulate the intake of fuel for the idle, low and high speed settings on the engine. Regularly checking and maintaining a properly adjusted carburetor will add years to the life of your carburetor and to the FS80R. However, over-adjusting a Stihl carburetor can cause serious damage, as the engine will quickly overheat. Make only adjustments to the idle and low speed screws as necessary.

Fuel container
Freshly mixed Stihl fuel
Screwdriver
Wrench
Small screwdriver

Instructions

- 1
  Drain all remaining fuel leftover from the last use into the approved fuel container. Dump out any fuel older than one week. Fill the trimmer, at least ¾ full, with freshly mixed Stihl fuel, using a 50-to-1 gasoline to oil ratio.
- 2
  Unhook the box cover holding the air filter inside. Pull the filter out and slap it against the palm of your hand. Wash it in clean, soapy water and rinse under cool water. Air-dry the filter thoroughly before reusing it. Mount the cutting head tool with the screwdriver and wrench if it's not already mounted.
- 3
  Turn the screw marked "H" (for high speed) counterclockwise until it stops, about ¾ of a turn. Screw the "L" speed screw clockwise slowly until it reaches stop. Move the screw back counterclockwise one full rotation.
- 4
  Start the engine and allow it to warm up to operating temperatures. Turn the "LA" or idle speed screw clockwise and counterclockwise looking for the highest RPM setting before the clutch engages and the cutting tool starts moving.

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