Running string trimmer without head

[dennis]

Working on a Homelite string trimmerI, UT20680. Before I buy a new trimmer head, I want to see if engine runs and can be tuned to specs. Can this be done without the trimmer head and string installed? It has no trimmer head.

[Skywatcher]

Hi Dennis

It is safe to start and idle a trimmer with no trimmer head, just don't hit the throttle as the engine will over rev and possibly destroy itself. The resistance of the filament through the air at operating RPM is a necessary load that controls the engine top RPM. Yes, the high RPM can be controlled to a point by carburetor adjustments, but it's always best to run the unit with a trimmer head installed. All the best,

Sky

[bgsengine]

Working on a Homelite string trimmerI, UT20680. Before I buy a new trimmer head, I want to see if engine runs and can be tuned to specs. Can this be done without the trimmer head and string installed? It has no trimmer head.

Yes and no - You can run it without the head, but do not run it at full speed more than a few seconds, and don't even *try* to "dial it in" without the head and the correct length of trimmer line (to where the line cutter trims it) or you won't ever get it to run right. They are designed to be run with the correct line length - too short (or no head) there is no load so the engine will run way too fast and burn up - Likewise do not run it with too long a line (without guard installed) because then it will cause high amounts of heat and friction in the clutch and engine works too hard, overheats and seizes.

[dennis]

Thanks, Skywatcher and bgsengine.