All I can add is that my M20 with two plain taps will get you from Aylsham to Swanton Morley, about 15 miles , on a very dark night on reserve. I'm pleased to say
Richard
I have got so fed up with leaky original tasp that I have changed ovefr to Bap taps on all my bikes. I get them in pairs (maoin and reserve). Admittedly a bit more fiddly to operate on the M20 due to the carb cables being right in front of them but a price worth paying for long term reliable taps.