Back in '71 I was taking my first road trip on my first BMW. An R60US. Running up Hwy 101 thru the Salinas Valley late on a Saturday afternoon.
Suddenly it started running on one cylinder. Simultaneously my left foot felt chilled. Must have been the gas pouring out of the carburetor. The threaded cap at the bottom of the carb managed to loosen itself and, who carries a spare of them? (Me as long as I owned that bike!).
I open my trunk and found nothing except:
My Buck 110 folding knife
My camera bag.... Which had the old 35mm aluminum film cans...
I hacked the film can to fit around the Housing the cap fell off and taped it in place. Gas still sloshed out but at least it ran til I got to the closed Honda BMW dealer in Salinas. A few of the guys were standing around in the parking lot and when the saw the predicament told me they doubted they had one in stock. Ended up taking on off a trade in.
When I got home to LA the following week I promptly bought one of each cap and the corosponding gaskets. Where ever that bike is now, I'm pretty sure those caps and gaskets are still in the tool kit.