Sounds like your rings are stuffed. Try changing them and your oil - old dirty engine oil also causes your exhaust to smoke.
Sorry, as no-one else had done it, I had to!
Yes - I have quit many times as well. I do manage to get by on about 7 to 10 a day though. Go out riding more. I find its difficult smoking and riding at the same time - can't get the cigarette under the helmet without breaking it, or burning my nose.
Gum also helps - just regular Wrigleys or whatever. When you want to smoke, chew a piece of gum and take deep breaths. Just don't try to light the gum!
Good luck!
Cheers
Dwayne