A little progress from today:
OiltankOiltank brackets tacked on, ready to check chain-clearance etc:
ExhaustsThe CR75O exhausts are a 'big' part of the appearance of the machine, and something that I would like to get looking tidy.
I believe on the original bikes each exhaust pipe was made of two pressings, which were then welded or seam rolled together. This left the appearance of a seam running at the top and bottom of the pipe. The headers were formed separately and were welded or clamped to the pipes.
Although the shape profile could be achieved with rolling or even sand bending rolled cones, the appearance of a seam is hard to achieve
The obvious next step was to give it a go...
So a good chunk of time was spent today trying out hydroforming! Something that I have watched many videos on and read about but never tried.
Quick trip out to pick up various fittings to allow the cheapo pressure washer to be hooked up to the sheetmetal assembly, tapped hole in the blanking plug for bleeding air out of the system:
The hardest part of the CR exhaust shape is the curve, so the first flat pattern was knocked up to test the curve profile section. Complete guesswork for the angle and diameter (scaled off of photographs) at this stage and purely for experimentation:
Seamed together and valve welded in:
Hooked up, with a little safety cage!
Pumped up around 400psi
Happy for a first attempt, but very wavy edges and some buckling
The pattern next to the product:
Round two!Stainless sheet, smoothed pattern shape, special attention on matching the two halves and having smoother curves:
The latest attempt above the first attempt and pattern:
What I have learnt about hydroforming today is that the pattern, weld penetration and consistency are key to repeatability.
And that it is with a bit more experimentation I could possibly achieve what I am after...
I think I am going to purchase off the shelf header pipes, however I may experiment with another process I have been wanting to play with for a while which is sand-bending...
Cheers,
CR21