Oil out of exhaust slip joint

New to this forum. Thanks for allowing me to join. Bought a ’86 350X that was smoking a little. Took apart and put in new valve seals. The bike was set up with a 250 carb. Started it, which was a total PITA. Bike ran with no problem other than hard to crank (compression) and the butterfly wanting to stay closed and no smoke. I have since gotten a 350 carb..don’t know why but much easier to crank. It started smoking out the exhaust with the 350 carb and started noticing some oil dripping out of the slip joint on the exhaust. I find it hard to believe it wouldn’t smoke with one and smoke with a different carb. I think its coinincidental. Not trying to chase ghosts. What would make it drip oil out of the slip joint on exhaust? Starts right up and idles. Thanks for any help I can get