I assume you mean with the air filter off the unit . This will not harm the saw for a short term duration (5 minutes) Ensure to have the fuel tank full of fresh fuel and conditioner if using Ethanol fuel . Best long term results would include clean filter & new plug . Check spark plug colouration after a few hrs use to ensure proper fuel air ratio , since you did not have air filter on when tuned . You may find the mixture a little richer than 1st antispated. All the Best !

No actually the air filter will still be on. The plastic top cover of the saw will be off. L, H, and T screw adjustments are easier to get to that way. Just don't want there to be any chance of engine overheating due to top cover being off.

Steve: Tuned a lot of Old Homelites don't recall removing Top , other than the Throttle Stop Screw . What Year Decade is it ? Perhaps one of the Newer Home Depot Units with Clam Shell Design . If so then should be fine for a short tuning duration.

Looking at some U tubes, I
noticed some of the housing were removed to easily adjust the carb. I feel that could be the ref and concern. Without this housing the cooling air does not
have a good defined direction. I feel
the approx 5 minutes will cover the issue. OR! Do
not let the Cylinder's fins get too hot to touch might be a Ref.