Just wanted to pass on some info. for those who may need it in the future. a. Stihl FS100RX string trimmer 4 Mix with Stihl C1QS88 carb. I used a Zama carb. kit # RB-114. Cost $ 12.95 at one dealer that I use. Stihl dealer wanted $ 38.00 for the Stihl repair kit. I was having trouble with the machine running, so I cleaned the carb with Wally-*art carb cleaner (spray) and then installed the Zama kit. I do use the Stihl low smoke oil mix for this unit. b. Stihl HS 80 hedge trimmer. Was having trouble with this unit running. Ran like it was starving for fuel. Changed the fuel cap and carb. kit. No good! The pick-up tube inside the tank was pinched. Put new one on and good to go. Hope this helps!