I bought a 2001 Kawasaki bayou 300 4 x 4 and it was running awesome. I parked it and went out of town for a few days and it got cold here, I had fuel shut off and I was pull starting it but my arm was getting tired so I got a new battery and tried starting it and it normally started right off the bat first try maybe the second with the choke of was cold out. Now I have adjusted the screw under the carb I’m assuming it’s the fuel air mix. but I cannot get it to start now any ideas, I’ve reset the fuel air screw to 2 1/8, and checked the Spark the plug is a little black I’m going to replace it.

 

First thing is check for a spark. If you have a spark, clean the carb out, never alter the fuel air mix, if it ran fine before dirt got in, it will run fine once you get it out, unless you start messing up the air/fuel ratio.

 

There is also a dran screw at the bottom of the carb, you didnt adjust that one did you?

 

Also Look up what the factory settings are for that screw, Some times they are 2 turns out from full close but that will vary by model and possibly year as well. A side note turn screws full closed upon disassembly, Count turns as you close it, then mark those numbers down.
Carbs are very touchy, Good luck with your maintenance. Happy Riding