Do you have the air filter on the carb? Got to have one. If you have one , clean it if there is a round wire mesh in the side hole of the air cleaner.
Is the black stem on top of the carb pulled up all the way? This is the choke. You are supposed to push it down by hand when you attempt to start the bike. The choke stem is supposed to come up all the way when you twist the throttle full range. If it doesn't use a little WD40 and some fine steel wool to polish the choke stem so it slides up and down properly.
Did you check the oil in the transmission? Puchs have a wet clutch. Puchs made a one speed (round external cover on right side of engine) and a two speed (oblong or rectangular cover on right side of engine.)
1 speed takes 5.5 ozs of ATF type "F" . Filler screw, slanted screw on side of cover near the bottom.. If ATF runs out it's full.
2 speed holds 9.5 ozs ATF type "F", plastic twist type filler plug on top of tranny case. Use only 9.5 ozs. (DON'T top it off or overfill it)
Did you oil your chains and is the drive chain on the left side adujusted to the proper tension.
Are the brakes adjusted too tightly?