Posted by Bob in Illinois [162.158.75.253] on Monday, November 11, 2019 at 19:09:17 :
In Reply to: Stihl chain saw posted by Jerry In Idaho [108.162.246.152] on Monday, November 11, 2019 at 18:21:01 :
I have had several pieces of small power equipment over the years that have suffered from a similar affliction. I would always focus on the carburetor. Take the entire fuel system apart over and over with no success. One day I realized that the carb was really only half of the combustion cycle. This particular chainsaw happened to be an old Mcculloch. It was a beast but lost power over time. Turns out there is a screen in most two-cycle engine exhaust mufflers intended to prevent any flame or sparks from exiting the engine. Possibly igniting fires. Anyway those screens can become obstructed with carbon eventually choking off the flow through the muffler. It starts to present at higher RPM until eventually you can’t run it up past idle. This comes from improperly mixed oil/gasoline. Disassemble the muffler and clean it out. Might be your problem. Good luck.