Hi, not sure if this has been answered before. My bike has been sitting for some months, and while riding it for the first time it ran fine up to 5000rpm, but over that it began to miss, backfire and lose power very badly. I'd drained and refilled the tank with fresh fuel prior to the ride, but didn't drain the fuel bowls. I thought it might clear its throat after a few goes but it seems to be getting worse. Any ideas on what I can try or whats causing it? I have next to no mechanical experience!