Homelite chainsaw carburetors come with adjustable low- and high-speed screws, which allow you to control the amount of air mixing with the fuel at high and low speeds. While the carburetor's low and high limits are factory-set, for safety reasons, over time and after a carburetor cleaning, you'll need to adjust the screws to ensure optimum performance of your chainsaw. Improper adjustment of the screws can damage the engine, so you should not undertake this operation without the proper equipment and knowledge.
Clean the Air Filter First
Open the cylinder cover with a screwdriver. Remove the air filter and clean it by hitting it against your palm and wiping off as much dust as possible with a rag. Wash the filter in warm, soapy water if it requires extra cleaning. Wipe the area around the filter with the rag. Open up the front of the muffler with the screwdriver and remove the spark arrestor screen. Clean the muffler and screen with the rag and brush. Put the air filter back into the chainsaw once the filter dries.
Add Fresh Fuel
Fill the chainsaw tank with freshly mixed chainsaw fuel. Start the chainsaw and let it run on a high idle for five to 10 minutes to allow it to warm up to operating temperatures. This is necessary for proper adjustment. Do not adjust a carburetor on a cold engine.
Adjust the "L" Screw
Make an adjustment to the Homelite chainsaw carburetor screw marked "Lo" by turning it to the left. Stop turning the screw once the engine starts to whine. Turn the screw as far as easily turnable to the right and note the different effect on the engine's sound. Move the screw somewhere in between the lowest and highest settings for an optimal adjustment; wherever the engine sounds its best. This takes practice and a good ear to discern the cleanest, smoothest engine sounds.
Homelite Chainsaw Idle Adjustment
Set the idle speed screw by adjusting the screw marked "T." If the chainsaw starts and runs without idling, turn the screw clockwise to increase the idle speed. If the chain moves while the chainsaw is idling, turn the screw counterclockwise instead. The chain should not spin while the saw idles.
Set the High-Speed Screw
Adjust the Homelite chainsaw carburetor by turning the high- and low-speed screws as needed. Set the high speed screw by adjusting the screw marked "H." Pull the trigger so that the throttle opens as wide as possible. Turn the screw to the left and note the engine performance. Stop turning the screw when the engine starts to make a high-pitched whine. Turn the screw to the right and note the performance. Move the screw somewhere in the middle until the engine sounds its best. Some Homelite chainsaws have a plastic stopping device that limits adjustment of the low and high speed screws. The company recommends taking a faulty chainsaw to an authorized repair center if the chainsaw's speed cannot be properly adjusted with a slight twist of either screw. Do not overtighten the screws or force them far beyond their limited adjustment range.