Motorcycle Repair: Smoke!, valve seals, tail pipe

Question
I recently got my 72 yamaha xs650 out of storage and after I replaced the spark plugs, one tail pipe is smoking alot.  Probably simple, but I'm not sure where to start.

Answer
William,

-the pipe may have water condensed in it that is burning off.
-once you have run it a bit with fresh fuel,
check the compression on both cylinders.
-It could be stuck rings or maybe some
hardened valve seals.
-It might help to run some Seafoam type
additive through with the gas.
-check if both carbs are opening at the same time (carb synch)