Scooterotica

I recently fitted a 12.5 litre tank (along with fuel gauge that worked off a battery on the bench but not on the scoot but that's another problem).
Before this it was running well , new RT kit 130 miles so far running in 26mm Delorto with a Clubman through rubber elbow and foam filter.
The tank and MB regulator were the only changes before going out yesterday , so nothing that should cause problems.
Yesterday struggled under acceleration and top end , seemed better when accelerating very gently. Don't think any of the filters can be blocked as this was the first run since I filled the tank. Flicked the choke on while riding but that made it worse.
Have,'t had chance to try with the pannels off to see if it's not getting enough air now there is less space with the new tank.
Could it be as simple as reduced air flow? What are the filter options? I don't really want to run open mouth.
Thoughts please guys.

Have a look at the filler cap breather. Possibly not flowing enough air thus reducing fuel flow.
SF

i ran a Breathsweet type filter on my Avanti with no problems (3000 miles). Changed to a 12.5 L tank and had to re-locate the filter to run horizontal instead of vertical.......still didn't like it and now run open mouthed.

Thanks Spanish Fly,
I did check this before the running in started , just drilled them out a bit to be sure though.
On the plus side just tried a battery feed to the fuel gauge earthed to the frame and at least that works , just need to sort a feed out or get a dry cell.
Mick , that was what I was thinking. I did exactly the same , stopped tried another angle still not happy. Might be open mouthed then.
Thanks.