The carburetor on an Eager Beaver chainsaw is adjusted at the factory to its optimal settings. Over time, however, the carburetor will need adjusting to maintain that optimal setting. Improper carburetor adjustment can lead to serious engine damage, which will void any remaining warranty. This is why manufacturer McCulloch recommends you take your chainsaw to a professional service mechanic if you are unqualified and don't want to risk damaging your engine.
Things You'll Need
Freshly mixed chainsaw fuel
Locate the high and low carburetor adjusting screws. On older models, these screws will be located on the clutch side. On newer models, they may be located on the starter side, next to the primer bulb.
Unscrew the top cylinder cover with the screwdriver. Take the air filter out. Clean the air filter in warm soapy water or replace it, if it's dirty. Don't make any carburetor adjustments with a dirty air filter. Unscrew the muffler cover, and clean out any buildup of carbon with the brush and rag.
Fill the chainsaw with fresh gas. Start the engine and run it at a high idle to warm it up. Locate the low-speed engine screw.
Insert the screwdriver into the low-speed engine screw. Turn the screw clockwise until the engine starts to surge. Back off the screw counterclockwise until the engine starts to run heavy. Find the position between the heavy and surging settings where the engine sounds the best.
Find the screw marked with an "I" for idle speed. Insert the screwdriver, and turn it clockwise until the chain starts to spin. Back off 1/4 turn until the chain stops spinning. Never set the idle speed so the chain is spinning while idling.
Leave high-speed adjustment screws to a professional with a tachometer and a good ear for the proper maximum engine setting.
Setting the high speed screw beyond its maximum will ruin your chainsaw.