FZS 600 '98 model Under powered at 3/4to full throttle

[bobertsoft]

Hi all. I'm new here. Please excuse me if I ask a question. I have the same problem as the chap above. I don't have any prob starting hot or cold. When the engine is in neutral the rpm's will struggle all the way up......smooth up to about 4500 to 5000....struggling from there on. But when riding its a different story. It struggles to get past 4500. Same bike...same year in fact. Any thoughts....or am I looking at the same issues as you've all discussed already. What confuses me is that the rpms will go all the way up in neutral but not when riding. 
I'm a real newbie at all this...sorry to impose. Thanks, Robbie