I’m working on a custom, one-off exhaust system for a Yamaha XV-TR1. This has quite a few steps. Firstly I need new flanges to bolt the exhaust up to the cylinder heads.
If I can buy exhaust flanges with a few minutes searching on the web, then I’ll buy them, as thats generally quicker and cheaper.
However, if I can’t buy them, I have to make them.
These are the steps involved, and I’ve inserted a video below to show you, in eight minutes, how I did it.
- Measure the existing exhaust flange or exhaust port in the head
- Draw up the flange (I like to do it in scale, so I can confirm it is OK).
- Transfer the drawing to steel (I used 6mm mild steel plate).
- Roughly cut the flange out with an angle grinder.
- Grind and sand smooth.
- Drill the manifold bolt holes.
- Bore out the exhaust port hole (in this case – 44mm diameter – done with a holesaw).
- Quick clean, take off the sharp edges, and sand on the flat bench (mainly for looks).
Once the flanges are done, the exhaust build can start. The following two-part video shows a time-lapse of the build. The pre-bent sections are available online from exhaust/auto suppliers. This is one way of fabricating a custom exhaust. After doing a few of these it become easier, but you have to visualise how pre-bent sections (45, 90, 180 degree bends) can be used as-is, cut or modified to create a shape that you see in your head. You can see from the start of the following video that I had done some planning beforehand, and used this sketch to plan out what bends I would need (before I ordered them). Obviously the customer shouldn’t pay for parts not needed, so the planning process is part of making sure we don’t waste money on the build.
Contact me if you have any questions!