I can see the fuel in the tank bubbling like mad and there's a constant stream of air bubbles going to the carb.

The manual advises that the tank should be wrapped in foam but the holes in the formers are not large enough to allow this. I put foam when I could but the tank will still be touching the formers. I suspect that this is causing the problem.

It's not easy to take out the tank and install an anti-foaming clunk. Are there any other options ?

Thanks