I messed with the "idle adjusting screw" (a black **** located behind the carbs)
and the bike either won't start or revs so high I have to shut it down

Sometimes it'll idle too high and then rev itself way down to the point where it stalls out

I can't find a "set point"

Any suggestions?

 

I messed with the "idle adjusting screw" located behind the carbs
(a black plastic **** you turn with your fingers)

Now I can't get the bike to start

It'll rev way too high so I have to shut it down, or it won't start at all!

I can't find the "set point"

 

Welcome to the forums davehayward1

Did the ride run properly before you messed with it?

 

You just have to mess with it while the bike is warmed up and running with the choke off. It shouldn't make your idle go crazy like you say it does.