Small Engines (Lawn Mowers, etc.): Carb adjustment for Kawasaki engine, kawasaki engine, carbon deposits

Question
Hi Eric,
I have an older John Deere riding mower, SRX75, with a 9hp Kawasaki engine.  Every couple of months it starts running rough, especially under increasing load, like turning uphill, and dies.  It will restart (with throttle at idle), but run rough.  I pulled the plug (very heavy carbon deposits) and cleaned it.  Seems to run well. It doesn't smoke or use any oil.   Is there some way to adjust the carb a little leaner?  Which screw is high speed (on the carb body?) or low speed (near the carb to engine mount?)? What are initial settings? Which way makes them leaner?  Is reading the plug the best way to fine tune it?  Thanks, Ed

Answer
Most of those carbs are leaned by turning the needle in and most initial adjustments are 1 1/4 to 1 1/2 turns out from a GENTLY seated position.

Is the air filter clean?  When was the last major tune-up?

Reading the plug is a very good way to check the engines health.

Is the intake gasket leaking?  Has the carb ever been rebuilt?

Let me know.
Eric