if its hard to start/keep running/keep tuned, you have a piece of (cant say on a family site). my stihl starts up in two pulls after a winter, i also drain the tank and run the lines dry before storage too. A good commercial grade trimmer is tighter in emissions/engine tolerances than your average consumer grade crap, there is no smoke coming from my exhaust.

 

Some good responses to this thread. I for one was also wondering about the 4 cycle trimmers. I know you can operate a 2 cycle in about any position, but now that they offer the interchangable attachments I wonder how well the engine is lubricated when it is operated upside down? With the 2 cycle you can do anything with it and not worry about starving it of oil/lubrication. Do they have some sort of pressurized system to get around this?