Speed Triple Petrol Tank Overflow Fittings

Anyone know what thread the overflow fittings are on the underside of the plastic petrol tanks?

They are smaller than 1/8 bsp, Larger than M6 but smaller than M8. An M7 tap will start but bind so not that and surely nobody would use a non preferred size, and, you can't buy M7 fittings. I have access to push fit plastic connectors and was hoping to save a few quid over original parts.

Cheers
Nigel