Starting on the tail-chop was very difficult for me. I've never done this kind of thing before. I didn't want to make a mistake and cut-off too much, and it was tough to really visualize what it could look like when all I could see was the bare frame in front of me. I deliberated for hours each night, sitting on the ground in front of the frame trying to picture the design in my head.
Here's what the existing tail section looks like without any frame covers:
Here's what it looks like from the top with the rear fender missing:
(notice the location of the cross piece in relation to the battery. This piece will be cut off, shortened and moved forward. I need to shorten it because I want the new seat to sit closer to the frame than it does stock.)
Here's the rear-end marked up for the cut:
(you can see I've already ground out the welds on the frame. On the right you can see the raised square piece on the frame that the stock seat rests on. This will get removed.)
Here's the first cut:
I started slow and then cut-off more later. (again the square piece in photo center gets removed)
Marking out to cut the angle:
And now the angle cut. This took a while to get just right, and required a lot of grinding to get even.
And after the cut, mocking up the position of the cross piece and trying the new tail-light on for fit: (you can now see where I removed the square piece from the top of the frame)
I salvaged this tail-light off a '97 Honda CBR600 that I found derelict in an abandoned warehouse in Alameda during some of my travels. It just so happens that it fits right between the ends of the frame and hides the end cut. I decided to use this model of tail-light after much research and looking around. I then ordered a new clear version with integrated turn signals from Clear Alternatives that I'll use instead of the red lens one. The raw ends of the frame will get covered in some kind of rubber shielding, after the powder-coat, to protect the tail-light.