Stihl 070, 070AV, 090, 090AV, 090G Chain Saw Service Repair Manual. Stihl 088 Chain Saw Service Repair Manual. Stihl 4137 Powerhead Service Repair Manual. Stihl BR 320 400, SR 320 400 Blowers / Mistblowers Service Repair Manual. Stihl BR 340, BR 420, SR 340, SR 420 Blowers / Sprayers Service Repair Manual. Stihl Chainsaw 311y Repair Manual Stores are decking the halls, and the radio hums with holiday music, signaling the arrival of fireplace season. Before cutting logs for the fire, make sure your chainsaw is in good working order with Stihl chainsaw parts.

Stihl Chainsaw Carburetor Adjustment

All Stihl chainsaws have just three carburetor adjustment screws, so fairly easy to work on when you need to a Stihl Chainsaw Carburetor adjustment.

(LA) Idle Speed screw – This controls the engine speed at idle. If set too low, the saw will die. If set too high the chain will run. This is dangerous.

(L) Low speed adjustment screw – This is the low speed jet. This is the adjustment that controls the air/fuel mixture at idle. Adjust this screw too rich and the chainsaw will blubber and die at idle speed. Adjust this screw too lean and the engine will starve. The saw will race or surge. An extremely lean adjustment will also cause the engine to die.

(H) High speed adjustment screw – This is the high speed jet. This is the adjustment that controls the air/fuel mixture at high RPMs. Adjust this screw too rich and the chainsaw will blubber, too lean and it will over rev.

Safe Basic Settings

Screws (H) & (L) – Turn the adjustment Screws (H) & (L) down onto their seats (clockwise). Back them off 1 complete turn (counter-clockwise)
Screw (LA) – Turn (LA) Idle Speed screw until the chain stops. Then turn counter-clockwise one quarter of a turn.

Stihl Ms 391 Chainsaw Manual

Fine Tuning – Screw (L)

Stihl Chainsaw Model 311y

Erratic idling behavior; poor acceleration – Idle setting too lean; turn low speed adjusting screw (L) counterclockwise until engine runs and accelerates smoothly. Readjust screw (LA).

Exhaust smokes at idle speed –Idle speed setting too rich; turn low speed adjusting screw (L) clockwise until engine speed drops. Then turn screw back one quarter turn and check that engine still accelerates smoothly when you open the throttle. Readjust screw (LA).