Ethanol is the culprit,you can seal it with after you made the tank,using peel ply will give you a good surface to bond,also pst cure your tank,vylonester resin offer good heat resistance.

Hmm, could be a PITA to source.  Maybe a small Ali inner tank with a carbon dummy tank around that....Loose out on capacity though.

Hi Steve, to quote Warren at Easy Composites

Any idea what this coating is called?  I suppose it'll have to be ethanol proof due to the amount they put in petrol these days....Mine is a plastic tank anyway and has a couple of bubbles due to this and my brother has an Aprilia and his tank has swolen a lot, so much so that he can barely fit his seat and the front of the tank almost touches the headstock.

You need a special coating on the inside to be able to handle the fuels. 

Hi all, I've been having a look on the site at the various kits etc but before I get any further I have a quick question.  I'm thinking of making a petrol tank for my bike - what would I need to do for this?  I'm assuming I'll need some sort of iner tank or can fuel mix with carbon safely?  Has anyone else gone this route before?

Thanks in advance!