Stihl SH 56 C-E Instruction Manual - Page 17

Adjusting the Carburetor The carburetor comes from the factory with a standard setting. This setting provides an optimum fuel-air mixture under most operating conditions. With this carburetor it is only possible to adjust the high speed screw within fine limits. Standard Setting Fine Tuning for Operation in Mountains or at Sea Level A slight correction of the setting may be necessary if engine power is not satisfactory when operating at high altitude or at sea level. N Warm up the engine. At high altitude N Turn high speed screw (H) clockwise (leaner) - no further than stop. At sea level N Turn high speed screw (H) counterclockwise (richer) - no further than stop. Adjusting Idle Speed English Erratic idling behavior If acceleration is poor even though the standard setting is correct, the idle setting is too rich: N Turn the low speed screw (L) slowly clockwise until the engine runs and accelerates smoothly. If acceleration is good, the idle setting is too lean: N Turn the low speed screw (L) slowly counterclockwise until the engine runs and accelerates smoothly. 296BA010 KN 296BA011 KN N Shut off the engine. N Check the air filter and clean or replace as necessary. N Check the spark arresting screen (not in all versions) and clean or replace as necessary. N Turn high speed screw (H) counterclockwise (no more than a 3/4 turn) as far as stop. N Turn the low speed screw (L) carefully home as far as stop and then open it 1 full turn. It is usually necessary to change the setting of the idle speed screw (LA) after every correction to the low speed screw (L). Engine stops while idling N Check the standard setting. N Turn the idle speed screw (LA) clockwise until the engine runs smoothly. BG 56, BG 56 C, BG 66, BG 66 C, BG 86, BG 86 C, SH 56, SH 56 C, SH 86, SH 86 C 15