I was sorting through my collection of Amal carburettors yesterday (yes, some people collect these things--they make wonderful loving cups) and was surprised to see a remarkably large hex fastener as the drain plug on one float bowl. The correct plugs are plastic. Below, a picture of the bowl, with the arrow showing where the plug goes, plus the hex plug (left side) beside the correct plug:
Below, a close up, showing the inexpertly sawed-off bolt that appears to be 9/16" 20 threads per inch, which was forced into the drain which is internally threaded 9/16" - 26 TPI CEI. Nicely ruined the float bowl.
Really quite remarkable how ignorant and sloppy some home mechanics can be. Same folks who put self-tapping sheet metal screws into holes threaded for machine screws, or who use vice-grips as a substitute for wrenches (I've seen examples of both). These are the people who believe that the rule is to "torque it till it strips, then back off half a turn."