It does sound like you're running lean, with popping on decel and the hard starting.
What colour was the plug? Is it the right plug? Was it wet at all? What is the carbon build up like?
What kind of shape is your air filter in?
Any cracks in the intake tract? Everything seated and sealed up properly? Sometimes there may be a tiny crack in the intake between the carb and head causing a lean condition, and these cracks aren't always visible until you pull things apart.
I'd suggest taking the carb apart, cleaning it really good and then seeing what jetting you have in there. You may need to go up a size on the pilot to rich it up just enough, then spend a bit of time doing fine adjustments with things like the mixture screw and needle clip positions. How many turns out from seated is your mixture screw? If it's more than about 2 1/2 turns out it's too lean on the pilot. If you're not that far out, you can back it out 1/4 turn at a time to richen it, but there is a procedure to finding where it should be. The mixture screw isn't intended to be a "band aid" fix for proper jetting, it's a fine tuning mechanism to be used once the rest of the jetting is where it needs to be. It's handy to pick up one of those quick adjust mixture screws as they are a real pain to get to while on the bike, even more so when the bike is hot.
Last week I was having some jetting issues on the MX bike. Was running too rich in the lower RPM as I was getting on the throttle (it was running just like how 2strokes run until they "clean out"). I ended up pulling the carb off, taking it apart, cleaning everything and going down on my pilot size. Of course, once I got it back together I was very lean (shooting awesome snappy flames out the exhaust when slamming the throttle closed) so I now had a baseline and put my previous pilot size back in, and then made the proper needle position and mixture screw changes and I was good... This I learned from reading up on the net, what does what, when, how it interacts etc. There was a thread on the thumpertalk forum that was very helpful.
Eventually you'll learn to "listen" to what the bike is telling you, and experimenting is the best way to learn.
When you do carb work the importance is cleanliness. Think sterile clean. You don't want ANY dirt, grime, grease, fibers from your cleaning rag etc in any of the little ports. As you re-assemble, ensure everything is smooth and functioning, you wouldn't believe what a little piece of hidden dirt will do to a carb. I used a nice plastic bristled brush and a can of parts cleaner. Air compressor would be nice too.