Makita chain saws, like most saws, need continued maintenance to perform well. There are many key components, if missing or damaged, that will cause your Makita chain saw to cut poorly or stop running completely. These two-cycle engines require three basic things to start and run: fuel, spark and air compression. If any of these three key components aren't working right, you will need to repair the saw. Follow these simple troubleshooting tips to help isolate the problem, which will make finding and repairing the broken parts much simpler.
Verify that the chainsaw has fresh gas at a 50:1 gas-oil mixture and enough oil in the oil tank. Clean the air filter by slapping the felt band across your palm or other flat surface. Pour a little gasoline onto the filter and clean it with a toothbrush. Replace the filter if it is old or too dirty to clean.
Ensure that the chain slides freely around the bar and isn’t caught on anything. Release the chain brake and try starting the saw. If the saw starts but dies, adjust the high and low RPM needle valves.
Check to make sure the saw has air compression by pulling on the starter cord; if the saw has compression, the engine will make a whirring or chugging noise. The cord should neither be too hard nor too easy to pull. If it is, take off the side cover with a screwdriver and make sure the pull cord is attached properly. Replace the pull cord if it is frayed or broken.
Check the chain saw’s spark plug if the saw has compression but still won’t start after checking the pull cord. Remove the rubber plug wire from the spark plug. If the spark plug is dirty, remove it with a spark plug wrench. Pour a little diesel gasoline over the spark plug and scrape it with the toothbrush to clean off any debris or dirt. Screw the spark plug back into the plug connector but don’t attach the spark plug’s rubber plug wire to the engine. Let the plug wire hang loose near a metal part on the saw’s engine block.
Pull the starter cord and look to see if there is a spark from the spark plug. If there isn’t a spark, replace the spark plug and try the test again. If you still don’t see a spark, check the wires to make sure they aren't damaged. If the wires are functional, remove and replace the starter’s coil or the starter.
Confirm that the saw is getting fuel to the engine. Not enough fuel may cause the saw to idle and die or die while throttled. Remove the air filter cover and air filter. Hold your finger on the throttle to open the carburettor (the little metal flap that opens and closes when you squeeze the trigger) and spray starter fluid into the hole.
Try starting the saw again. If it still doesn’t start, check the fuel line to make sure gas is flowing from the tank to the engine. If it isn’t flowing, replace the fuel line.
Remove, disassemble and clean the carburettor if the saw still doesn’t start after cleaning and replacing the fuel line. Replace all of the seals and gaskets inside the carburettor. If it still doesn’t start after a thorough cleaning, you will need to replace the carburettor.
A majority of a saw's problems are connected to a dirty, broken or old carburettor. Storing saws for a long period of time will cause stale gasoline to dry up in the carburettor, which will need to be cleaned for the saw to run properly. If the saw still isn't working after completing these tests, you likely have something more serious going on inside the engine, such as a broken piston or cracked engine block, which will require a professional to fix.
Always use caution when working around gasoline and sparks. Only perform maintenance on saws in a well-ventilated area.