Cutting up engines to graft on more cylinders is the flavour of the month on YouTube, I’ve been an avid follower of Allen Millyard since the 90’s, and there are two Vietnamese guys (Le Dan, and another guy who’s channel’s name escapes me) who turn boring single cylinder scooter into V twins and triples, with really basic tools. Makes me want to build something too, but I’m too lazy, so I’ll stick with my twin engined bicycle.