[subxero]

As far as the jetting, get it running at WOT first. Don't worry so much about how it gets there just how it runs when you are WOT. Dial the main back until you get it running well. Then work on leaning out the needle clip and moving to a leaner needle all together if you have to. Then the idle - 1/4 shouldn't be too much of a PITA to tune. If you are running the stock carb. 38mm PJ i believe, they are not the best carb but they can work good enough. Most people opt to a PWK. I had a 39mm pwk on my 500, and boysen rad valve. It took a ton of jetting tests and changes but i eventually got it dialed in and it was electric.

As far as the pipe. Weld the crack then make 2 plugs, a solid for the exit and one with a shrader valve for the intake. Pump ~ 20psi of air into the pipe, then heat the dents with a torch, nothing too hot that you will burn through it. Handheld torch with MAP works. The heat will expand the 20psi of air already in the pipe and increase the PSI and force out the dents. If you get the dent nice red and hot and it is still going nowhere after awhile, pump a few more PSI into the pipe in small increments until it does.

As far as going fast on the 500, you are entirely correct, they get scary at high speeds, the chassis isn't designed for that kind of speed and the front gets so light very subtle unwanted inputs into the bars can cause big problems.

Here is a picture of my valve pipe plug for blowing out dents. Pretty simple, i just used couple pieces of angle and a piece of wood to create a clamp, cut a patch out of an old tube with the valve stem. Just sandwich it all together and it is good to go.

Good luck and have fun.