I have several pieces using Stihl's 4-mix engine and have never had a problems with any of them. The valve adjustment is over stated. A typically home owner may never have to do it. When it needs to be done it is so easy even a lawyer can do it.
Scag Tiger Cat 48-inch deck, Kawasaki motor
Lawnboy 10227 2T push mower
Stihl BG86 handheld blower
Stihl BR550 backpack blower
Stihl KM110R kombi system with lots of attachments
Stihl HS45 hedge trimmer 24-inch blades
Echo SRM210 trimmer