New Honda 2020 baaj 8 Idle adjustment

I have a new 2020 Honda Baaj 8 HP , I have broken the engine in and now want to troll . I got a hour / Tach and installed it yesterday. After the engine is warmed up it idles at 840-850 RPM. Is there a adjustment to lower the idle ? I wanted to troll at .5 -.8 MPH and with the throttle all the way back at idle the boat trolls at 1.1 MPH. The Propeller that is on it is a 10/6.5 . If I have to change the propeller to go slower at the same RPM which pitch should I get ?

There is a "curb idle" (automotive term) screw located on the side of the carburetor closest to the engine. However, 850rpm is actually a fairly low idle speed for this engine so I'm not sure how it will "like" turning much slower than that. But, you can try backing it out a tad and see what happens. There is also an idle mixture screw on the side of the carb but it isn't intended to be used and it is covered by a tamper resistant "cap".

As far as prop change goes you would want to go with a lower pitch to slow it at idle. I know people will disagree with that as a lesser pitch typically increases top speed and reduces torque but we're talking idle here and inches forward per revolution.
I have no idea what pitch would get you where you want to be.

Good luck.