ULEZ and how it effects the Gen1:

[mtread]

The TFL site says they must meet Euro 3 and suggests that will mean registered after July 2007.

But looking at the detail of Euro 3 https://www.transportpolicy.net/standard...emissions/
That means :
Over 150cc 0.15 g/km
Less than 150cc 0.80 g/km

So that's the target.
Seems a bit daft that little bikes have a higher limit :rolleyes