Zama Carb RB-k75 Hidden Screw Adjustment

[oli]

I just finished rebuilding a Zama RB-K75 carb on an Echo SRM-210 trimmer. As part of the process, I removed the "hidden" high speed adjustment screw. I neglected to bottom out the screw to determine how many turns out I should back it out when making the preliminary adjustments. How many turns out should this screw be for the initial adjustment. What should the wide open throttle RPM's be? Thanks in advance, Oli

[KE4AVB]

The info I have says 1-1/2 from seated as initial setting. Tune for max speed then enrich to drop 50 rpm.

[bgsengine]

To add- with a string trimmer, you wanna do your adjustments (usually) with a set length of string sticking out (usually just a bit shorter than hitting the line limiter) .. trying to tune it with no string , you gonna see much higher RPM's (and risk getting it way too lean)..

[38racing]

Saw a youtuber adjusting one a week or so back. Knowledgeable guy on 2 strokes but I felt it necessary to unsubscribe after his short video threatening to cut someone's head off with a mower blade over something on tiktok.