Running rich

went out for a ride yesterday and there ws a distinct small of petrol when i stopped at traffic lights. this ties in with it being a bit funny on choke. So im thinking its runing rich. Is there a way to adjust it? and how?

Also when going along a mate said they i had a large bit of smoke pop out of the exhaust. twice in an hour. first time it was black. next time it was white. But the bike was running fine and both were revving it a bit. Any ideas?

Smoke coming out the back .... I had this when the local garage overfilled my SV with oil , so check that for starters . I`m sure one of the more knowledgeable guys will be along with correct advice regarding the choke etc .