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Rattle-y Gas Cap

B

bobinthemtns

New member
I've got a '77 r100s with the anodized gas cap with the bmw logo on it--
But the thing rattles loudly at lower rpm's- I've tried locking it, screwing to the point of racheting, but because of it's spinning design, it still buzzes like crazy...

Any fixes out there?
 
Quick and easy solution without replacing the cap is cut a small piece of rubber tubing into one inch or less lengths and put one or two of them in the well on the tank. They will keep the cap from vibrating if you get the right size tubing. The cause of vibration is not due to the cap being loose, but the inside ratchet mechanism on the cap is worn. Happens to most of them, if not all over time. Still, no reason not to throw it away.

Wayne
 
It's been recommended not to ratchet the gas caps...it's a different design as compared to you car gas cap. Continued use of the ratcheting mechanism will break off the plastic tips inside and the cap will be stuck on and you'll have to go through more steps to physically remove the cap.

Should the cork be changed to how tight the cap fits to the neck?
 
Thanks for the info guys-
And yeah- I don't purposely ratchet the cap- it just seems like something begging to break and then you're screwed.. or perhaps unable to unscrew as the case may be-

I was debating to fixing it solid with a drilled screw.. but I'll try the rubber tubes first to see how that works-

Thanks guys!
 
Okay! I tried the easiest solution first, and it worked like a champ! Simple 5 inch (or so) piece of fuel line I had laying around unused... Wrapped it around the tank opening and screwed the cap on, and voila! Zero rattle!! And if I ever get in a pinch and absolutely, positively need 5 inches of fuel lines... Oh yeah! Haha...

Thanks for the help guys!
 
When the cap rattled on my 81 RT I found some slop between the two parts. I just went around gently peened the edges to tighten things up. Maybe that is your problem?
collage of gas cap.jpg
 
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