I'm working on a Suzuki GSXR1100W 1994, with K&N dual pods filters, 4into1 headers and 40mm CV carbs for a customer. I've cleaned the carbs as usual with an ultrasonic cleaner, bought new emulsion tubes, seals, fitted a Factory pro stage3 kit 15mm float level and balanced Now I have a problem that I can't solve. Cruising at maybe less than 1/4 of throttle opening it gets rich until it fooled the sparkplugs. The enrichment comes a fraction of second before the needle valve start to raise even spitting fuel outside. I've tried to play with the pilot jet (stock 40) going from 32,5 to 42,5 and moving the needle until the first position from top. It gets leaner everywhere but the problem remains. Of course going to a leaner pilot circuit the strange enrichment gets slightly better, but the problem remains.
I suspect that a previous work on that carbs, somebody trying to clean them has enlarged the transition ports at a point of no return. Does anyone have a solution for that?