Is operating a trimmer engine at low speeds or part throttle bad for the engine?
Very unlikely. In fact, lower speed is better. Essentially, light trimming at part throttle reduces the adverse stress effects on the engine itself that are created by high RPM’s. A low speed trimming operation is also much more pleasant with reduced noise, vibration and thrown objects. While each engine may behave differently, it is recommended that occasionally you rev the engine to clear any residual fuel from the internal engine and muffler and continue to revert back to a slower RPM operation. As a further suggestion, many engines, whether run at low or high speeds may begin to experience exhaust screen clogging which tends to choke the needed air flow through the engine. Follow directions in your trimmer’s operator manual. Remove the screen, clean and replace it. You’ll see how much better the engine will operate. Always use the oil/fuel ratios recommended by your trimmer’s manufacturer. Don’t use excess oil, it will clog the screen faster (More is not better). Rarely, some engin
