I would take it back to whoever did the work. Maybe they screwed up something, but for the life of me I don't know what it could be.
Maybe I mis-read this; when you said the front wheels locked up and you had to get towed back to the truck, I was assuming that you meant that the front wheels locked up (as in would not turn). Now it sounds like you're saying that the front wheels are turning, but the differential is locked (like the yellow lever is pulled in).I have an 05 BF 650, I took it last week to have recall work done on the front end. They replaced the A arm and other parts on it. Well I went riding today for the first time since I got it back and was there maybe 15 minutes when I switched to 4x4. I then switched back out and both front wheels locked up completely. Got pulled back to the truck and the front end actually freed up. So I rode a little more in 4x4 to see what would happen and when I switched to 2 it locked up again and was popping a little. If any of you have any input , it would be greatly appreciated.
Camo Joe, you have to be careful lying to the dealer like that about not driving it, Most dealers record the mileage on the work orders to prevent this kind of thing from happening to cover there own butts. It is also normally required to record the mileage for warranty claims. Just a heads up for everyone