I’ve just replaced the exup valve on my gen 1 after running it without for a month or so. The previous owner had the bike into a ‘carb specialist’ as it wasn’t running right with no valve. He apparently richened up the mixture and it ran ok. It’s already been dynojetted, and there’s a R/R printout for 131 bhp and 75lb torque exupless. Not too shabby!
I replaced the exup, and it feels like there’s 10-15% more mid range now, the bike runs better, and I’m getting better fuel economy too.
I don’t nail the engine too often anyway, as my commute is all town work, so why the hell would I want all the power up near the red line? 👍