Well thats prob because the carb needs a good cleaning. By what you've told us, the clutch bushing sounds like it's dry and binding up. This would cause the bike not to roll easy or not at all. I've got a Manco out in the garage now that is bound right up tight from sitting outside. Take the clutch apart, clean it up good and oil the bushing. Make sure you oil ONLY the bushing and you should be good.
Vic