As someone who has ridden the road to Batopilas and once owned a rigid Harley with a suicide clutch, I'll offer my opinion for what it's worth. The road into the canyon is not technically difficult, but is heavily washboarded in places, and in others there are sheer drops of several hundred feet, with no guardrail. I would not hesitate to do it on a street bike, but I think a hardtail would be torture on the washboard. If you go, plan for a long, slow, hard ride. I took me just under 4 hours to get from where you turn off the paved highway to Batopilas, stopping to take pictures, and 2-1/2 hours getting back out, hauling ass to beat nightfall. This was on a KLR 650, so on your Harley, I would figure 50% longer. To me a highlight of this trip is the mission at Satevo, about 6 miles past Batopilas, and that road is much rougher. Lots of loose sand, short but steep hills and loose rock. I would not take a foot clutch bike there, although someone will say it's no problem for them.
Almost forgot, plenty of places to stay in Batopilas, so stay overnight and walk out to Satevo in the morning.
[This message has been edited by AndyT (edited 03 April 2004).]