Hey Jester
I've been going through a very similar issue, that I think (I hope) I have finally solved.
Is it worse when the bike is warmed up?
Long story short, I think I accidentally found the culprit. Check the fuel line routing just before the injector/throttle body.
I happened to find mine was kinked, badly, and I'm guessing as my bike warmed up, the hose got softer and pinched/restricted fuel flow.
I usually leave my shrouds on when removing the tank, so I never saw the line till I happen to take the left side shroud off and there it was, kinked like crappy garden hose.
It would explain why, in my case, the bike would work great for a couple laps (I race supermoto) then start acting up...(getting worse when the bike warmed up and the hose got more compliant?).
I've installed a hard line, 90deg elbow, just off the injector with hopes this fixes it. (hose no longer is bent over to reach the injector)
For the record, I've been chasing this thing for a while.
I have replaced...
Tip over switch, Spark plug, Cap, Coil/Plug wire, Fuel pump & filters, even the pick up coil at the flywheel.
It's been on a factory diagnostics computer and showed no faults at all...totally stumped us. I've not a chance to run the bike hard yet to see if I've finally fixed it. I'll keep you posted!
