1977 R100/7 Gas Cap

[jpluist]

I have a '77 R100/7 which has been untouched in my garage for many years. The key works in the ignition and frame lock, but wouldn't turn in the gas cap, which would only rotate about 20 degrees. I have drilled out the cylinder and can see what appear to be the threads on the inside of the cap (about 2.5" diameter & 2" deep). Now the cap rotates 360 degrees, but I can't get the cap off. Have tried turning the handle while lifting it with a good deal of force via a rope, but no joy. Any other suggestions on how to remove the cap?

[Kurt in S.A.]

Welcome! Likely what's happened is that the cap locking feature was used and it was twisted on to hear the ratcheting noises like you hear on a car gas cap. Shouldn't be done on these caps. There's a way to defeat that mechanism, but it doesn't involve drilling such a massive hole in the cap. You can try this on Snowbum's page about half way down:

https://bmwmotorcycletech.info/fuel-caps-airheads-K.htm

in the "Ratcheting, unscrewing, re-keying" section.

If that doesn't work, about all I can think is that you'll need to continue to drill out or collapse inward the rest of the cap. Obviously it's toast. Wish you could have tried something like above first! Good luck!!

Kurt

[jpluist]

Perfect response. I drilled a hole at 15/16" radius and inserted a tight-fitting nail which did the job. Was then able to unscrew the cap. Thanks for the most helpful and thorough reply.

[SteveD]

You've probably seen now that it's apart that the top is just crimped and is part why it can usually be pulled out. That technique is suggested as: rope thru the handle then around the back of your neck whilst standing on the pegs. Stand up hard and fist...and bingo! hopefully it pulls out.

[mkj]

My cap suffered the same but at a petrol station many miles and I was without tool. I forced it out with by the handle sadly this distorted the tank and now the cap sits off centre and a new locking cap will not fit so I use the old one.