its supposed to smoke its a 2 stroke engine worry when it doesnt smoke,if its really badly smoking and has no power then the exhaust may be blocked with carbon from the burnt 2 stroke oil and the excess smoke will be from the oil in the exhaust burning with the heat as a blocked pipe will run very hot and also the gases that come out of it will be very hot too as its forced out of a small hole the gas heats up.
adam bike doctor, May 2010