You probably either have too lean of a pilot jet or an air leak somewhere either in the intake or the left side crank seal. I would try to go up a bit on the pilot before anything else. I'm also assuming that your slide is closing all the way down to the stop (Idle adj.)
Defintely do a search on this... we beat this topic do death not too long ago. To a degree, you'll always end up with a bit of a high idle on a cold start with choke. Personally, as soon as the revs start to come up, I flip the choke back down, I'll go on and off with it a few times if its real cold out. Now, some people will say the high revving with the choke on indicates that the pilot or air screw is set too lean. While the high revving with the choke on when the bike is cold can and often does indicate too lean a pilot circuit, it is also just the way some bikes, like my YZ is. If your getting major revving, I'd look into adjusting the pilot circuit, if your just getting some, and the bike doesn't need choke for a long time, your probably ok. You didn't give much info on the bike, is it in good mechanical shape? Has it always done this? How does it run other than this?
Did it run OK before doing the top end? If so then 9 times out of 10 the throttle cable is not seated in the top of the carb and it's pulling up on the slide. It's easy for it to get pulled out of position when putting everything back together. Twist the throttle and let it go. You should hear the slide bottom out in the carb. If not then check the throttle cable routing and make sure it's seated in the carb. Some times it pulls out of the throttle housing too so check that too.
If you have verified that the cable isn't the problem then look for an air leak. Don't mess with the jetting until you have exhausted all other possibilities first, especially if the jetting was OK before doing the top end.