OK, finally got my 89 GS 500 trackbike together and took it out on some WOT runs. 1-3 runs great all the way to redline. In 4-5 however at around 6krpm it just wont pull past that. Valves are done, havent done a throttle body sync yet. No vacuum petcock, full gravity system, single 1/4" line with 1 fuel filter.
Current jetting is
Pilot: 40
Main: 125
Needle: Shimmed 1 #4 washer
Air mixture screws set 3 turns out
Intake/exhaust stock
Any ideas? Maybe the main jet is too small to handle load at that range?
Obligatory pic
(http://i178.photobucket.com/albums/w241/catch2otwo/gs500/IMAG0184_zpsf411a83f.jpg) (http://s178.photobucket.com/user/catch2otwo/media/gs500/IMAG0184_zpsf411a83f.jpg.html)
Do a carb sync before anything else, my 93 has the exact same jets, washer, air screw settings as yours and after the carb sync it was a whole different bike. Before it would struggle just to get to 75mph now if I am not careful I can see triple digits (OK well 110 maybe) :) Although I still see a 5-6k stumble, once its past that it pulls strong. Do the sync and let us know how it goes.
Yep I was going to do a sync this week, just figured id pick peoples brains before hand. The jetting seems to work well for alot of people that are stock.