Just picked up a 1989 NC30 that needs some TLC. Looks like it's been fitted with a wrong battery and the earth lead has been bodged. New battery is on order, however could anyone please post a pic or two of how the earth lead is supposed to run and where it attaches on the frame or wherever?

Thanks in advance, not so new bloke

The earth goes from the negative terminal on the battery to the nearest lug on the LH side of the frame. About 20 cm worth of wire.

On mine it connects to LH side of sub - frame from neg battery terminal

The standard battery is supposed to be a YTX7A-BS, though the more common YTX9-BS which is a slightly taller battery, fits fine and has a bit more 'cranking power' (8-9ah); useful especially in Winter!
Here's a photo of where the Negative(-) battery lead connects on the frame: