Hello
1974 DT100 trying to find out where these wires go to (sorry pics won’t upload)

2 black wires come out of the main wire loom and together end in a ring terminal
2 black and white wires coming out of the main loom and end together in a female connector. 

Pic Pic

Pic

 from Salisbury, UK.

Pictures upload issues a real downer at the moment. 

Anyway, the black wire with the ring end (M6?) is almost certainly an earth and can be attached to the frame at any nearby convenient point - underneath the coil is a typical site. Just make sure that it is a clean metal on metal contact - ie there isn't any powder coating getting in the way.

Assuming that your loom is standard, hasn't been chopped around, is routed correctly and all electrical components are present, then there should be a black and white wire with a male connector in the arc of your female one. From memory, black and white might be the engine kill switch.

Thank you for your help.