Home / Shop By Part Type / Petrol tank parts / Tank vent assembly Tank vent assembly £25.00 £30.00 (inc. VAT) £25.00 Add to your Wish List Info Reviews Petrol tank vent assembly. Thread is M12 and the securing nut measures 29mm across flats. 'Barb' on the exit spigot measures 7.40mm diameter. Not yet reviewed Write an online review and share your thoughts with other shoppers! Be the first to review this product.