This is an add-on to the first Custom-Built Exhaust Pipes How-To article by McGoo at Biltwell, Kyle at Lowbrow Customs is working on his Triumph, a '77 T140V motor in a '70 front loop with a David Bird hardtail. He is using the Biltwell Custom Exhaust Pipe Kit, which contains 1.75" OD exhaust pipe and assorted HD exhaust flanges.
The same principles are used from McGoo's article, including starting at the head (in this case a piece of 1.75" tubing that fits over the exhaust spigot on the head), and working your way back, cutting and tacking pieces of tubing to get the proper angles and curves you want.
The spigots on a Triumph head are 1.65" outside diameter, and the inside diameter on the exhaust kit is about 1.64". To be able to clamp the pipes at the head you can just take a grinder with a cut off wheel and cut a .5" notch into the pipe on either side, that allows it to fit over the spigot then compress when you tighten the finned clamp at the head.
This entire set of pipes was completed from start to finish, including the time to figure out a design, in a Saturday morning, about 4 hours not including the final mounts on the rear of the frame for the exhaust. It was completed with a TIG welder, a cut-off saw, 4" grinder, some flap discs, a couple files and a sharpie marker.
Keep checking the fit of your pipes as you go, and as you complete a section you can grind the welds down for a nice smooth finish. Spend the extra time getting proper fitment before you weld to ensure a nice, seamless look.
The right-hand pipe that crosses over the the left-hand side is made of 7 individual pieces. Kyle eyeballed, marked, cut and fit each one with trial and error. He used the shovelhead flanges from the Biltwell kit towards the rear of the pipes to be used as mounting brackets by welding some tabs to the frame, and finished the pipes off with a set of 1.75 OD Brass Exhaust Tips.
So with the exhaust kit, some basic tools and some patience a unique set of custom pipes was finished on half a Saturday, with exhaust tubing and a bunch of flanges left over. Kyle's fabricating tip: if you plan on welding all weekend check your argon so you don't run out on mid-day Saturday.
A great piece of advice from Derrick (hatchethairy on the JJ): "For all you tig-tackers, try using some hose clamps with holes drilled in it to hold your place while you tack. trust me, it makes a world of difference in time when fitting and welding a set together."