Finally had some time to resume with the 500cc Runner.
Resumed with making the fuel tank bigger at the front.
Filled the tank with water, and it holds 8.8 litres now.
Thats more then enough for me.
The original tank (old type) holds around 8.5 litres, so its a small improvement.
And its not my daily driver, just for fun.
Made the places where the welds are extra strong by melting in stainless steel mats.
And over these mats i melt some extra HD-PE.