It's a PA6 nylon issue
PA6 nylon is "hygroscopic"
It was used because it moulded easily (pour in the mould, rotate and swirl it around) and paint sticks to it well. Typically it's a white creamy colour and usually not coloured.
Later tanks went over to a different nylon that's black but it is almost impossible to paint so began the trend to hide it under panels that could be painted.
* An after thought. The newer black ones do suffer from expansion when they get hot, it's just thermal expansion so they shrink back on cooling. Didn't some numptis push the cover panel a bit if left in the sun?
Harleys just fitted (even) smaller tanks, on the XR1200 it was a common problem
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"The final measure of any rider's skill is the inverse ratio of his preferred Traveling Speed to the number of bad scars on his body." Song of the sausage creature
Last edited by Nickj; 18-09-2021 at 12:02 PM..
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