The Stihl HS 80 requires the same basic maintenance as any small two-cycle engine. Regular maintenance, following the procedures in the owner's manual, should prevent most problems. Repairs within the abilities of most homeowners are simple and basic problems that are easily isolated. Without regular care, several different problems may contribute to hard starting, loss of power and other common troubles.
Check the air filter first if the engine fires, but is reluctant to start. Find the air filter cover on the left side of the engine--the choke lever connected to a mechanism inside. Set the choke to the fully closed position. Press down on the locking tab and slide the cover free. Dirt caked on the foam air filter prevents air from reaching the carburetor.
Clear debris from around the carburetor intake before removing and cleaning the air filter cartridge. Wash the cartridge in ordinary soap and water, and dry the cartridge completely before reinstalling the filter and cover.
Check the spark arrestor screen on the muffler exhaust port if the Stihl hedge trimmers runs, loses power and dies. Clogged spark arrestors prevent exhaust flow and suffocate the combustion process. Find the muffler port at the right side of the engine.
Remove the screw in the upper right corner of the Stihl HS 80 muffler when the engine is completely cold. Slide the spark arrestor screen out and clean it if needed. A light brushing with a brass wire brush removes most carbon buildup. Replace the damaged or severely clogged screen.
Check the spark plug if the engine runs poorly and emits smoky exhaust. Fouled plugs should be cleaned or replaced, but dirty air filters or too much oil in the fuel mix may be the real cause of the problem.
Adjust the Stihl HS 80 carburetor settings to prevent stalling or constant movement of blades at idle speed. Be sure the plug, filter, exhaust screen and even blades are clean and working properly before changing carburetor settings. Find the carburetor adjustment screws on the top of the left side of the engine near the air cleaner.
Adjust the L screw--the screw toward the front of the engine--while the engine is warmed up and running. Screw the control clockwise until fully seated, and then back off one complete turn.
Correct stalling by turning the LA screw--the control screw toward the back of the engine--clockwise. When blades move, stop and back off 1/2 turn.
Stop blades from moving idly by turning LA screw counterclockwise until the blades stop. Then, turn the screw 1/2 turn clockwise.