O-Rings have arrived. All the sizes fit. I'm leaning toward fitting 23 x 2.5mm between the tap and tank as it seems to protrude more from the body of the tap, the 2mm one protrudes but I'm thinking it's better to have a little more compression available rather than a little less.
The bowl one, both look ok TBH, but I'm thinking the 2.5mm might be better as the ID means it's fits the bowl better. I'll test it and see.
The doughnut and new bowl have also arrived. The doughnut is actually 3.5mm thick so I've ordered some 4mm Viton sheet and if I need to I'll sand it a little thinner but I'll test fit it first. All the 4 holes seem to be the same size, which is odd as the pics make them out to have at least one slightly bigger. I'll try a 4mm punch and see if the hole is large enough, if not I may need to order a 5mm one. The diameter is 20mm, in case anyone else is considering doing this. It's also very supple, they don't seem to stay that way for long though. Most of the ones I've felt were hard as rock.
If it all pans out I may sell a set of 2 rings and a new doughnut for £5 inc P&P. Approx £25 for the same in genuine Honda parts and they'll most likely be Nitrile not Viton.
