It sounds like you were having the same problem that I am having with my 85 550. It had the rev limiter removed when i got it and does not want to run smooth no matter how much I tweak the carb. It sounds like you have found the solution. What exactly did you do to fix this problem? Restriction in the return line? What did you use, how did you do it, etc? Any help will be apreciated as I am pulling my hair out as well.
Thanks, Joe
Thanks, Joe