Mk 1 fuel cap seal

Does anyone know where I can get a Mk 1 fuel cap seal from? I’ve tried making one out of neoprene but it expanded & isn’t very good. Ideally I’d like to use what Moto Guzzi use.
I’m not sure if the reason that the one that I made expanded may be the same reason that my floats started to pinch between the posts in my carbs. I blame the fuel we get nowadays.

I believe he is referring to the LM1 chrome flip-up locking tank cap, it has a sprung inner part that presses down on the filler 'ole and which has a large circular tap washer like type thing. Mine was starting to get ropey as well, someone else’s problem now! Point of note, for the last few years MOT’s require working filler cap seals able to prevent fuel running out if bike falls over. Just FYI HTH
Mike H2014-08-10 16:48:46

That’s the item Mike & yes the cap has to seal properly.

Are they different from the T3, Mk11+111?If not would make life easier.

Could be no, actually, basically it’s the flip-up lockable chrome cap. Turn key, it wants to flip up immediately (on a spring). Yes sure I’ve seen same style on other models. So worth asking reboot?