Dont try to over analyse a problem straight away. Start with basics - Have you tried thoroughly cleaning, servicing and blowing out your your carb?? Any muck or water or build up of old gunge at all especially in your pilot jet will make bike run like crap!!! Check for any dirt / excessive wear / missing/broken parts / float height and condition etc... It should all be as clean and serviceable as a surgical tool!! Have you replaced the spark plug / ht lead or plug cap??
Good luck mate - you never know - a lot cheaper starting point than timing and removing flywheel issues.
jumbostu
Team Yellow