Stihl MS 201 Instruction Manual - Page 42

English Engine Management Adjusting the Carburetor Exhaust emissions are controlled by the design of the fundamental engine parameters and components (e.g. carburation, ignition, timing and valve or port timing) without the addition of any major hardware. General Information The carburetor comes from the factory with a standard setting. This setting provides an optimum fuel-air mixture under most operating conditions. Preparations N Shut off the engine. N Check the air filter and clean or replace if necessary. N Check the spark arresting screen (not in all models, country-specific) in the muffler and clean or replace if necessary. Different Standard Settings L N Determine the required standard setting as follows: Turn the low speed screw (L) carefully clockwise as far as stop, then turn it counterclockwise. Is range of adjustment more than 1 turn? N Continue with "Standard setting A" Is range of adjustment less than 1 turn? N Continue with "Standard setting B" Standard setting A 0011BA039 KN Different carburetors are installed at the factory. A different standard setting is necessary for each of these carburetors. Standard setting A - High speed screw (H) = 3/4 - Low speed screw (L) = 1 1/4 Standard setting B - High speed screw (H) = 3/4 - Low speed screw (L) = 1/4 H L N Turn high speed screw (H) counterclockwise as far as stop (no more than 3/4 turn). N Turn the low speed screw (L) carefully clockwise until it is against its seat, then turn it back 1 1/4 turns 0011BA016 KN 40 MS 201, MS 201 C