I just sold my 1999 Banshee to buy a bike, I'm 6'2" and just south of 200lbs. I've decided that I want to enter the bike world and was thinking a yz125 wouldbe a good place to start. I odnt want to buy a bike and ending up having too much for my skill. I want somethin to learn on, then eventually step up to a bigger bike!
I've been riding a 1996 YZ125 for the past three years now and weigh 196 myself. The bike has more than enough power with minir tweaks. I put an extra tooth on the rear and boyesen reeds in it. You might want to put some heavier springs in it though. When you take it on a track you will be surprised how much power it has. I love it!
BTW I am 6'3" and would recommend getting a top triple clamp of of a 2000YZ if you get a YZ from 1996 to 1999 because they will give you more room in the saddle.