I have screwed up the adjustments on my caburator. My manual has instructions on how to adjust low speed jet, but does not have instructions on how to adjust high speed. Can someone help?

 

Get going down the rode around 50 MPH and screw set it at base setting and ride down the road about 50 screw it out till it starts running bad the screw it in till is runs smooth and has as good of acceleration for a 45. It is best to run a little on the rich side! Been years since I while since I rode a flat head. I have had both a 45 and a 74. One time I rode my 45 from Georgia to Virgina and back. Rode the 74 all over south east.