Gas Cap Leak

Hi All -

I've got a '73 250WR with a NOS gas cap which, of course, leaks like a sieve. I've used billet replacement caps from Husky-Parts in AZ in the past, but they are no longer available.

Do you guys have a fix or source for a non leaking cap?

Thanks for your help with this.

Just checking back on this post... any ideas for a leak proof but vented gas cap? Below are pics of my current tank / cap.

You may want to try the later vented style Husky cap with a spigot for a tube at the top:

https://www.hva-factory.com/frame-fixings/husqvarna-vented-fuel-cap

Hard to tell from the pic, but you may want to take some 400 or 600 grit wet/dry and smooth out the top of the tank opening - looks a little uneven there. After a while most tanks have no paint at that contact point anyway. Wrap the wet/dry around a flat piece of wood (or sanding block) to keep the surface level.

As a last resort, make a gasket of a bit thicker material than the original cap gasket from a sheet of Viton.

Vinskord makes a good suggestion. I don't like paint on the tank bung because todays fuel eats the paint over time. I prefer a clean bung for the cap to seal too. The pics below show how to take a bung mess and clean it up.

Another another leak problem with the Cawi cap comes from the thin paper shield inside the cap that allows vapor to pass through but not the fuel. After 50 years the paper degrades and fuel leaks. The same cap was used on maicos and pentons from the same era, so any of that aftermarket stuff will work.

Every tank I have painted, I do not paint the sealing surface of the bung. Look at street bikes. No paint. I learned the hard way on a showroom restored Honda 305 scrambler. When you paint the sealing surface, gas fumes will leach under the paint. It will work its way to the body of the tank. Yup...I got fumes under the paint. Unscrewed the cap one day and pulled off bout two inches of paint. Had to redo a beautiful paint job hoping it would match. BTW, do not buy the $ 40 to $50 gas caps. They are repops. I purchased three new ones at Mid-Ohio for $10 EACH.

Heart breaker and pisser at the same time.

Thanks for the help. My tank was recently repainted and I've had some damage to the clear coat on the first race due to the leaking cap. I'll remove the paint from the bung and level it out. I'm hoping the leak isn't through the venting portion of the cap - don't know how to fix that...

Yeah, don't paint that part.