The downpipes were usable once the ends where they went from 4 in to 2 had been cut off, a massive bonus as I don't have the kit to bend pipe without kinking it.
I suspect this arrangement might have lost a couple of horse power.
Starting to take shape, new brackets will be needed, the rear stays should be round tube with flattened ends, I will sort that later. New fixing brackets will be added to make sure the exhausts don't move about and fatique.
In case you haven't seen my other articles on this build, the bike came with 2 reverse megaphone exhausts but the 163 had 4 so another 2 will have to be made.
The two that were on there were quite badly done, the brackets were simply horrible and didn't really match up with any mounting point and they didn't come anywhere near far enough back and were at the wrong height and angle, apart from that they were fine. I used some video of the original bike at the motor museum as my reference point and various replicas I had seen had the exhausts in various positions, I want mine to be as close as right as I can get it, I have a bit of a problem in that I don't have any good way of bending pipe but the headers looked usable.
First job was to take everything off the bike and cut the headers so that I had 4 separate pipes terminating at the bottom of the engine. They were arranged so they had good clearance and the retaining collars at the head end were done up tight enough so I could still move the pipes but they would stay put against the force of gravity.
All splendid so far, the angles are not perfect but I feel I can work with it and make it splendid.
Next was to cut away all the nasty brackets, much care was needed here to not cut in to the metal of the silencers themselves, that would be a real pain. I left a bit of material and finished off with the angle grinder, they look fine now.
The original has two hangers at the back of the bike that hold the exhausts in the correct position, the outer exhausts point out and up, the inner two run a bit straighter, the two are joined with small welded on tabs, that will be one of the last jobs. i referenced the original to work out how far out the pipes needed to be, it's kind of dictated by how far out the rear wheel spindle comes, it's obviously important that misses the exhaust when the suspension goes up and down. I used the wheel rim to check that both sides were the same, the brackets on there are usable but I had to shorten them a fair bit and bend them to a better shape, I'm happy with them now but I may replace them with tubular ones when I am finished to make it more authentic. For now they are perfect for holding the exhausts in place while I work at the front end.
The down pipes turned out to be exactly the same outer diameter as the inner diameter of some 38mm exhaust pipe that I had left over from a previous project. This was a real piece of luck as it made fitting it all up extremely easy. I cut the tapered exhaust at the point where the inner diameter was exactly 38mm so the tube slid snugly up the inside of the pipe. It all holds together nicely like that, when I have both sides correct I will tack weld it together so it can be taken off the bike and fully welded. Some days things just work out all by themselves. I need to et some more pipe to do the same trick on the inner two pipes but I have been able to check my pipe runs and it's all looking good.
I now have to make the pipes themselves, they are very simple affairs but I have never formed a tapered pipe before so things may get interesting. It's really thin so should bend easily, it will be mild steel, the bike's not going to get much use and will live in the dry, stainless is a real pig to work with when all you have is basic and tools.
bit of paint makes all the difference.
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