Fuel cap rubber seal, AN part number 06.7102

Is it possible to replace the fuel tank filler cap rubber seal without dismantling the entire fuel cap assembly? The fuel cap on my 1974 MK 2 Commando 850 has the centre rivet not the screw connection. The rubber seal on my cap is in pretty rough shape and I’d like to just remove the old one and slip a new one in place without taking the whole assembly apart. It looks like it might be doable but I’d appreciate advice from anyone who might have attempted this. Thanks.

Yes you can. I did mine.

As above, can be done without separating the two plates. But, quite easy to drill out the rivet, tap in a small bolt. These extra few steps gets you access to the rubber bit of non-ethanol resistant and likely now long crumbly, hose for simple replacement. That bit of rubber hose is what actually makes the large gasket seal on the tank neck, not the spring.

Make sure you put the ribbed side on the tank side.

I have found the AN rubber seal to be less than successful. The rubber escapes the metal washer parts. Too soft? Don't know but
finally just put the rubber on the tank neck and close the cap down on top of it. Doesn't leak. Stupid but there you are.

My original tank cap, new seal fitted, leaked while riding bike. Solution was to renew the bit of rubber hose beneath the cap plates as described earlier. The original bit of hose was hard and crumbly. This hose is what applies all the pressure against the metal plates and thus the sealing gasket to filler neck.