Yeah, I don't think they're intended to be mufflers so much as spark arresters. Thus the regulations in most State/National Forests. If a tiny piece of sawdust makes it through the carb and into the combustion chamber, it's coming out as burning ash, and probably resulting in a fire if the conditions are dry. This is especially true with chainsaws since they rarely have anything more than a fine screen for an air filter. In California, I'm sure they've decided any 2-cycle engine with no spark arrester causes cancer somehow, whether it runs or not. IIRC, they recently banned ALL engines under 25HP?
I wonder if sometimes folks are letting their air filters get dirty which would make them run richer too. As soon as it starts sooting up, it can only get worse unless there's some sustained high-speed operation to get the screen hot and burn off the crud, preferably before it gets bad enough to restrict the exhaust. But it probably isn't terribly noticeable until it's too late if it isn't being run hard.
The engine on my Husqvarna B-185 blower is pretty quiet. It's relatively new (though I don't remember when I bought it) so may have the spark arrester in it. Might be time to take off the muffler and see if it's getting stopped up. Now that I know about this problem, it'll probably become my nemesis. Sometimes, ignorance is bliss. Never even thought about the addition of spark arresters to 2 cycle engines. Have seen them on some 4 cycle stuff to prevent big flames from the muffler when it backfires.
I remember the ancient Poulan that we had for firewood when I was a kid. It had NO muffler, and must have weighed at least 80 pounds. I could barely lift it into the Jeep. You could actually see the piston through the exhaust port and see the still burning exhaust come out of it above the bar at full throttle. That thing was LOUD. We mixed very rich for that thing and it would slobber half-burnt oil all down the front of the crankcase. IIRC, that thing wanted something like 30:1 mix to keep it from overheating.
