Hi and welcome.
PieEater has pointed you in the right direction regarding the EXUP valve. It's possible that yours might even have been removed or disable by a previous owner, in which case you would notice a flat spot lower down the rev range.
More info on the year, mileage and condition of your bike would be helpful.
I haven't exactly retired my toolkit yet but other commitments mean that I can't make as many Ivanising trips to the UK these days as I used to. A lot depends on demand, too ...
I'm weighing up the possibility of a trip in August but that depends on a few other things which I won't know about for a while yet. I'll contact everyone on my waiting list directly by e-mail but if you'd like more information, use the e-mail address PieEater posted above.