Still inclined to saying it`s a carb problem. Maybe the float needle is jamming in the #4 carb so it wont fill up? Or clogged jet

 

Welcome to the board! Without being there diagnosing skipping issues is difficult. Maybe your bike likes Glee

I'd take the carbs off completely, disassemble and clean thoroughly. Takes only a tiny speck of crud to plug needle orifice and cause strange issues. If it does fire and run lean on that cylinder you could end up running it hot.

Once cleaned it's easier to put the boots on off the bike and install carb bank as a unit. A smear of oil on the boot as well as making sure the boot is warm will work wonders.

Good luck!

 

Welcome to the forum and best of luck getting her reliably firing on all cyclinders