Small Engines (Lawn Mowers, etc.): Chain Saw, exhaust ports, adjustment screw

Question
Hi Marc... I have a Sears 18" chain saw that I bought new about a year ago. Here is what it is doing. It will start and idle fine. When you give it gas, it boggs down and dies. I have cleaned the plug, pulled the carburator and completely cleaned it. If you let it idle it will run forever, but when you give it any gas, it dies.

Appreciate any suggestions...

Thanks
Bob

Answer
If you have checked all of these things and re-assembled it correctly, I suspect it may be one of three things. Did you check the exhaust ports AND the spark arrestor in the muffler too?  What is most likely wrong is carburetor adjustment.  The starting point I like to use for the mixture screws is 1 1/2 turns out from lightly seated (low & high speed). The low speed is closest to the cylinder and the high speed is right beside it. The idle adjustment screw is not in the same proximity of the mixture screws. I like to set the high speed first. Hold the throttle wide open and begin turning the high speed screw in until the engine revs as high as it will go (this is too lean and don't do it for too long), then back it out 1/4 of turn (mixture will be sufficiently rich to provide power at high RPM). With the engine idling (you may have to adjust the idle screw slightly so it will idle somewhat normally), open the throttle rapidly. There should be no hesitation. Turn the low speed mixture in 1/8 of a turn and open the throttle rapidly. If there is still no hesitation, turn the low speed in another 1/8 of a turn. Keep doing this until you find that it hesitates, then back it out 1/4 of a turn. This will be sufficiently rich to provide power off-idle. Then you can fine tune your idle. The idle RPM is not critical except that it should be low enough to keep the chain from turning while idling.  Hope this helps.