Dyno with A/F meter make it easier. I found the needle setting of my TMR32 with help of a dyno run, slowly increasing throttle on 5:th gear from 2000- 6000 rpm.
Way too rich so I knew what to change. 1 step felt better but still wrong, 1 step further leaner and it felt right. Verified at another dyno visit
I verified main jets earlier this year when I changed from 4-4 to 4-2-1. WOT (around 200 kmh), slowly reduce throttle from WOT, if it accelerate, more fuel
I was very close to enter a car from behind so Dyno is better!
I have struggled with pilots and fuel screws for a while. Replaced coils fixed it so I could start over with various pilot jets.