the beam being fabricated from sheet metal, e.g. forming fuel tank walls

Full Title

Motorcycles, engine-assisted cycles or motor scooters with one or two wheels (fairings or streamlining parts not forming part of the frame B62J; transmission of drive from engines to wheels B62M) > Frames (motorcycles or cycles with auxiliary engines characterised by position of engine B62M) > characterised by the engine being between front and rear wheels > the frame being of single-beam type > the beam being fabricated from sheet metal, e.g. forming fuel tank walls