I have successfully printed a part about 75mm across in Taulman Bridge nylon with temps of 240/90 on the first layer and 250/50 on subsequent layers. It took me several goes to get it to print, in fact my first goes looked a lot like your picture. In the end drying the filament at 80 degrees C in the oven for five hours before printed seemed to make the crucial difference, once I had done this the print worked fine. I do not have an enclosure, the printer is sat on a table in the lounge.