smoke loss of power
if the smoke is black it may be that it is runing rich. on the other hand if it is bluish in color it may be a sign that the piston rings are starting to show wear.
Replacement piston rings.
you most likely have bad piston rings or in a overhead cam you might need to rebuild the topend
The engine would smoke and damage the bores.
Piston rings or Rich oil .
The Piston rings are probably worn causing oil to get into the combustion chamber which causes smoke when burned
broken piston rings maybe and oil gettin into the piston chamber.. too much oil maybe a blown head gasket... the smoke is steamy
Oil !
Engine "Blow-by" caused by excessive engine wear usually bad piston rings
It would be very rare for them to do so.
The pseudolink at the bottom will guide you to videos for this. youtube.com/results?search_query=how+to+blow+smoke+rings