wrong mixture???? (white smoke out of exhaust)

hi my bike is a yamaha jog n im tryna iron out all the creases to get it running smoothly .. there a a few problems with the bike ..what do u expect for 200..its sort of a little project for me while the weather is shite .. i presume the last owned has messed about with the bike due to it only haveing done 488 miles on the clock and still should be running smooth at that .. it seems bellow out a hell of a lot of white smoke wen revved up .. im presumeing the mixtures been tamperd with .. i dont no how it passed mot at the end of november if its produceing this smoke .. could any one give me some tips on what screws to turn .... is the mixture for the oil n petty on the carb or what ?? sorry about the essay... cheers ty

 

Or it could just be the fact of every 2 stroke smokes until warmed up properly, if started and revved without warming up then that cause be the cause..So my question is.. Does it smoke while idling or just when revved up?.. And a bike for £200 you want to be stripping it and checking it all way through to eliminate any problems it may have before they hit u in the arse! lol

 

sorry about the late reply .. i doesnt rele smoke at all wen idleing .. it has been striped down to the frame n engine .. and everything seems to be fine .. the only problem is wen reved hard to full revs for a few second the the revs cut out asif i have let off the throttle .. once reved agn it will do the same only at around the same rpm.. ( could this be some sort of rev limiter ) the bike is fine up untill i get up to this rev restriction ..i can ride it around fine untill i push it flat out on a straight .. if this is a limiter how can i remove/ alter this cheers ty