Pipes Of Peace!

Just what creates that gorgeous six sound? Allen reveals all...

The exhaust system for my RC374 had been on my mind for a while and I was looking forward to getting started.

I have made a few expansion chambers for my two-strokes and I have also made small megaphones for my SS100 V-twins so I’ve had a bit of practice, but these Honda exhausts were going to be harder to make. Firstly because they are so small in size and secondly because the genuine RC174 pipes are made from two pressed pieces that are seam-welded together along the top and bottom, which was a common way of making exhausts at the time. I wanted to replicate this look with my exhausts and had been thinking about different ways I could make them and researching photos online. Due to my slightly wider engine and the shape of the sump I would not be able to replicate the exact look but I was hoping to get them close. I had already made the header pipes for the test run of the engine and they were okay to use after lengthening the straight portions to fit alongside the frame rails and with a few minor adjustments to the curves.

I decided to make a start by cutting out cardboard cone templates to dimensions that I had worked out from my book of pictures. When I was happy with the shape I took the templates to my friend Bernie at Project Metal for them to be cut out of 1.2mm steel sheet on a guillotine. I also asked for several 6mm wide strips from the same sheet (I will explain what these are for later).