iv had this trouble b4. If you wanna take matters into your own hands then strip the bike down, give everything a damn good clean down! Fill her with Grade A oil, Coolant... The works! (Treat ya bike like a woman) B4 startin her up, Hold the front brake tight and bounce the front end, this helps move air bubbles sat in fuel line! Start her up (if she does) and let her sit for 5mins with the choke open. As you move off, close choke and get her to a nice bit of straight road and open her right up!!!! If this fails or your not willin to do this, Book her in for a service. Hope this helps