Actually, I pay even more attention to the throttle butterfly screw. Its location in an area of smaller area/higher velocity makes smooth airflow even more beneficial. When you take a close look at it, you will see that the head and exposed end of the staked screw actually occupy a fair percentage of area in the carb throat, especially on carbs this small to begin with. Smoothing both the throttle and choke screws should get you a measurable gain in your case. If it happens that it doesn't, I would then suspect that a low exhaust port timing would be limiting power increases. Some of the Ryobis had quite low exhaust port timing. The thinking most likely was, that by utilizing a quite small carb along with a low exhaust port timing, the engine would tend to rpm limit itself if/when the string broke on the weedeater, thus preventing engine damage.
AV8TOR
Last edited by av8tor1977; 10-16-2017 at 09:44 AM.