So recently bought a 1980 gs750l to have some fun with. So when the bike is in neutral you can snap rev it and gradually rev it above 3k with no problems. But when I decided to take it out for a ride under a load in 2nd through 5th it will just spit and sputter when it's in 3500 to 4k anything below is fine. Is it to small of a main jet drive bad vaccum needle? Also does adjusting the fuel screw mess with how much fuel the main jet gets or only during idle to 20 percent range?