We take a Stihl FS91R 4Mix trimmer that was dumpster bound and bring it back to life! Join us as we walk through the entire process of diagnosing and fixing this trimmer, including a full engine disassembly, cleaning out the goop that was clogging up the engine, and adjusting the valves to get everything running smoothly again.
The Stihl FS91R is a robust and reliable trimmer, but when it’s left to sit for a long time, moisture can wreak havoc on the engine. The inside of this trimmer was completely filled with thick goop, likely from sitting in damp conditions. In this video, we show you how to clean all that junk out, inspect the camshaft, and explain how the compression release works.
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