250 miles from a tank.

[stevierst]

I am going to drill a 2mm vent hole, that's all it needs, to aid filling, there is bound to be a good reason Yamaha designed it with an air gap though.
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I wouldn't bother with 2mm, there's already a 3mm hole there. I tried 5mm first, and it still took forever to get the last 2 litres in. Opened it up to 8mm, and it was better.
As for the air gap, pretty much all tanks have an air gap for fuel gas expansion should you experience a sunny day on the UK to leave your bike out and exposed with a full tank of fuel.