moving to 2-strokes

Let me guess..... He has tried to jump every jump that all the 80's do and has trashed his xr80 and now wants to motocross. He shouldnt have any problem!

hold on!

nah, he should be fine as long as he don't try to attack the throttle on the 2 like he did on the 4. make sure he rolls on the throttle easy cause it won't take much to get the front end up.

My son spent 4 months on an XR100 then moved to a YZ85 in September when he turned 13 (he is only 5'1"). I made sure he took it easy for the first couple of tanks of gas. He had no real problem at all switching. If anything he still tends to not rev enough, the XR100 had much more low end and he was use to short shifting. Even so after about 4 laps yesterday he started catching me. It looks as if I can only challenge him to short races from now on.
If he can touch the ground well enough to start it, and can pick it up if he drops it he shouldn't have a problem. He will need to learn to slip the clutch and not just rely on the engine torque when taking off and coming out of corners, that is about it.

My two sons (then 11 & 13 years old - now 12 & 14) rode XR-100's for about 7 months before moving up to CR-80's.
I had the same concerns as you. I had them ride a flat open field first to get the feel of the CR-80's power hit. They don't have the bottom end that the XR-100 did but an awesome top end.
After riding around a field for a while doing turns, figure 8's, fast straight-aways, and quick stops, we went to the MX track. They took to the bikes in a quick way. They learned much faster than I thought. They have been riding the 80's for over a year now and no problems at all. (except they probably ride better than me now!)
Just start him out a little slower to get the feel when the power hits.

Check out their links below to see how well they actually ride.

Good Luck!

I owned an xr 80 and stepped up into a cr 80. I'm just like your son...I was very good and trashed my xr 80 (It was in good shape, just bottomed alot). The step is no problem. Watch out for the powerband kicking in tho. I almost wheelied out the first time I rode my cr. Its like a plane, the front wheel just lifts off and before ya know it its wayy up there. You learn to control it though.