I wonder if the bike had been standing a while with regular 95 Ron unleaded in it.
Thats possible as well mate. As I say, it had done 620 miles in what would have been 2 years but it was brimmed to the top when BMW delivered it…mix of both in the tank I guess.
Anyway, I went to a classic meet in the Shropshire hills today, 250 mile round trip, was perfect throughout.