A quick update. I've been fine tuning (without the O2 sensor) and, as suggested by Jim, I went down to a 230 main jet, and, progressively, down to a [HASHTAG]#197[/HASHTAG] air jet. After playing with 45 and 50 pilot jets, I went back to a 40. Hallelujah! the bike has always run well, but it is now really running nicely. The best yet. Starting is easy and idle solid. With the bigger pilot jets you can watch fuel economy plummet and watch it improve when you go leaner. All in all, a really interesting exercise. I should have the O2 sensor plumbed in this weekend, so that should be fun. Also, another dyno run is coming up with my mate's Commando as well. He's had a TriSpark fitted, replacing a Boyer and a bit of fine tuning on his Mikuni. He was having a few starting problems, since cured.