just a thought when i wash the bike i then give it a good spray of wd 40 or similar on start up i get smoke as such from the front header pipes, it could be this that you have noticed it does smell a bit too but soon goes away.

hopefully it is nothing serious

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Ride On :tenere:Camel 2008XT660Z
harvey mushman did it in the dirt Uma 1994 TT250R