give it a general tuneup.. use Fred's Guide as a.. err. a guide. Since top speed is still available the engine and everything must be in pretty good shape generally.
It sounds like maybe your timing is off a bit .. and an exhaust leak can hurt acceleration... you've probably waited long enough and need to get down and re-tighetning bolts and nuts, adjust and clean up some stuff... get a new spark plug.
If it always smokes try cutting back on oil a bit.. If i run my bike at 25:1 it will always smoke.. but at 32:1 it doesn't.. and yet when the engine is disassembled there's a nice oil coating on everything.