Had 4 lower left molars pulled 50 hours ago. i really want a cigarette. what are the risks if i smoke at this point?

Many: Smoking can contribute to clot loss and bone infection (dry socket). I don't have to tell you that smoking causes mouth cancer, lung cancer, kidney and pancreas disease, contributes to colon cancer, increases heart attack and stroke rate, etc. Smoking is just plain stupid, so don't look for any doctor to tell you it's ok. You've gone 50 hours, more than 2 full days. Keep it up.

Rolling the dice...: Delayed healing, dry socket... Nothing good can really come from smoking, of course there is a chance you may be fine, but is it worth it taking the risk?

Do no smoke: Smoking can definitely hinder the healing process. Also, normally there are only 3 lower left molars, unless you had an extra one in the wisdom tooth area, or one of the teeth extracted was a bicuspid.