I picked up a saw at a local sale, with oft heard claim "It ran last year when I put it away, but now it just won't run". The price was right, so even if the cylinder was scored, as the other parts were worth more than the purchase price.
I got it home and cleaned the acccumulated crud to get a better idea what I was looking at. Dumped the fuel that looked to be mixed with "Red Armor", checked for spark and compression and both were OK. The crankcase must have been full of fuel, from trying to start it as it spit fuel during the compression testing. Pulled the plug and blew out the cylinder with compressed air to remove the excess fuel. Tried to start it, no joy. Thinking that old fuel mucked up the carburetor, I installed a new replacement unit I had on hand. A few pulls and I would get a few slow combustion cycles, before it would stop. It would do this over and over again, open butterfly or closed. Thinking I had flooded the saw, I ran the High and Low needle valves to their seats and pulled the saw over a couple more times. Not even a pop was to be had. I was just about to search through my stash of crankshaft seals, thinking I had a vacuum leak causing when I gave the cord a couple more pulls and the engine staggered to life. After about 30 seconds of low RPM operation a nasty smell pervaded the workshop, then a piece of some sort of bug was ejected out of the muffler. The spark screen of the muffler had been removed and some sort of bug decided to call the muffler a winter home. I'm still working to clean out the muffler, but I'm sure that this was the issue. I've heard of others having similar issues, but this was the first time it happened to me.
I got it home and cleaned the acccumulated crud to get a better idea what I was looking at. Dumped the fuel that looked to be mixed with "Red Armor", checked for spark and compression and both were OK. The crankcase must have been full of fuel, from trying to start it as it spit fuel during the compression testing. Pulled the plug and blew out the cylinder with compressed air to remove the excess fuel. Tried to start it, no joy. Thinking that old fuel mucked up the carburetor, I installed a new replacement unit I had on hand. A few pulls and I would get a few slow combustion cycles, before it would stop. It would do this over and over again, open butterfly or closed. Thinking I had flooded the saw, I ran the High and Low needle valves to their seats and pulled the saw over a couple more times. Not even a pop was to be had. I was just about to search through my stash of crankshaft seals, thinking I had a vacuum leak causing when I gave the cord a couple more pulls and the engine staggered to life. After about 30 seconds of low RPM operation a nasty smell pervaded the workshop, then a piece of some sort of bug was ejected out of the muffler. The spark screen of the muffler had been removed and some sort of bug decided to call the muffler a winter home. I'm still working to clean out the muffler, but I'm sure that this was the issue. I've heard of others having similar issues, but this was the first time it happened to me.