simple question

[recent400exbuyr]

just bought a 01 400ex dont know a whole lot about it its fun
any ways is it normal for it to puff black smoke its just a little each revolution? i also have a two stroke i know it will smoke but not sure if a four stroke should pleas help and if there is any other helpfull tip please tell

[GPracer2500]

Black smoke = rich jetting. A four stroke shouldn't smoke (any color).

Make sure your air filter is clean. Dirty air filters restrict air flow which richens your current jetting settings.

[krt400ex]

mines stock and it smokes a little when it's cold.