Mine doesn't do that, it will run on half or full choke as soon as I take the choke off, it dies entirely, I leave the choke on, and try giving it gas, and it'll backfire out both sides. Which is telling me not combustion all fuel, I've taken the carb apart a couple times, nothing is clogged left air fuel mix screw how it was, and cleaned the carb, re assembled a few days later, snapped a chain and had to replace the Magneto on my flywheel pulled it and hasn't ran right since.. and I took tha left side cover off today, and had score marks on side of my flywheel think I should get new flywheel and Magneto?

Check first your carburator settings to make sure that it is running properly and not choked. If that doesn't solve it then there could be something broken or messed up anywhere from in the clutch system to the gearbox depending on what the drivetrain is.