I had great luck with a Ryobi 26cc 4 stroke trimmer I bought reconditioned 7 years ago. The uppper drive shaft broke about a month ago, and I really didn't want to put $50-60 into it to fix, so I decided to try one of the Troy bilt 4 strokes, since they are basically the same as my Ryobi. I first tried the new "commercial" 25cc model, and it started right up but ran horribly. It sputtered and stumbled and had no power. Seemed to run very lean. I took it back and bought one of the cheaper 29cc models which is the "improved" version of my old Ryobi. It ran ok- once you got it started. It took me about 50 pulls to start, and I followed the starting instructions to the letter. Needless to say, it went back too. I ended up with a Husqvarna 128L 2 stroke, and it is terrific. It starts right up, has plenty of power, and runs very clean. I finally found a place that carries the upper driveshaft for my Ryobi and it's only about $30. I think I'll fix it and keep it as a spare. I think Troy-Bilt's quality went to [censored] when MTD bought them.