Originally Posted by Polwart
Finally there is no reason why a "very good engine" can't also be a bit smokey.
I would disagree with that , if a 4 stroke is smoking its using oil which means there is something wrong . Presuming the oil level is correct and the breather isn't blocked or some fool; has put 2 stroke mix in it then there is something worn which at least would require the cylinder head off .
problem with engines is that some sellers really do believe its ok when its not you do need to check it out before handing over the money .