Are you absolutely sure you set your timing correctly? Exactly how did you determine your current timing?
Also, what's the history of the engine? Has it been rebuilt with fresh seals and a roller crank?
A video of the bike idling, running and riding would be helpful to diagnose your issues. Could be as simple as having your jetting off. I don't use VM or mikuni carbs in general so I cant help much there.
Also, just to be sure, make sure your brakes aren't dragging. (edited)