difference between four stroking and lean bogging?

Well, I finally got my Newport put back together after finding the crunchy metal bits inside my engine. I was really excited to ride it...it's been since the Cranks rally. That's just too long.

I was excited to find out that the bike fired up and idled great after just 3 kicks. I quickly called another local mopeder and we went for a ride around town. The bike seemed great at first, but I quickly realized that the problem I had before this all started was still there. It pulls nicely up to nearly half throttle and then it falls on its face. If I left off a bit...it'll start to accelerate again. It definitely bogs out, but I have no idea if it is four stroking or lean bogging. What the heck is the difference? I mean, I know conceptually what the difference is, but I have no idea how to tell the difference while riding the bike. I feel like this is something I should know by now. Don't you?

After I got home, I realized that in my haste to ride this bike again, I completely forgot to:
A. Put any ATF in it. Nice job!
B. Tighten my spark plug more than just by hand. Again, nice job!

I fixed those items and took it out again, but it didn't seem to make a difference.

So, last night I checked the bike for air leaks. It may be leaking slightly between the cylinder and the head. I could hear a faint drop in RPM as I sprayed carb cleaner around that area. I was comparing that to spray carb cleaner right on the metal mesh air filter. I could definitely hear a drop in RPM there.

I then tightened up the head a little more and up-jetted from 82 to 86 on the main jet. I also down-jetted from 50 to 40 on the idle jet. I've been wanting to do that for a while.

I wonder if my crank ended up failing because I was actually running lean (air leak?), when I initially thought I was running rich. See...knowing the difference between four stroking and lean bogging really could have helped me out.

BTW, my Pinto is currently doing something similar. It doesn't run above half throttle. I've even heard it backfire a few times. Do you know how lame it is to ride kitted bikes at 20-25 mph?