Stalling while riding is a common problem with the 03 year. Everyone says kickstand, but that wasn't the cause for my stalling and couldn't find a solution anywhere online.
When it stalls it just shows CHEC, which doesn't give an error code. And sometimes it shows FI and gives C32, C33, C34, C35 (FUEL INJECTOR CIRCUIT MALFUNCTION). I tested it all and the fuel injectors are fine. Fuel pump and fuel filter are fine. Fuel relay is good.
So I bought my gixxer used and in the process of debugging, I found that the "Sensor Ground" line on the ECM harness was cut. It is cut as part of the bypass for the exhaust valve. It is cut in order to avoid getting the C46 error ("C46" EXCV ACTUATOR CIRCUIT MALFUNCTION) FI error.
For more info on the exhaust valve and why the "sensor ground" line is cut, see bugmanweb's page below:
The Sensor Ground line goes to a bunch of sensors like the Tip Over sensor, throttle position, secondary throttle position sensor, IAT sensor... The behaviour sounds like Tip Over? But once I re-connected Sensor Ground, it fixed my stalling. I sometimes get C46 error but at least the bike doesn't stall any longer.
My stalling begins after about an hour of riding. I have ridden for 2 hours, twice now and hasn't stalled so I'm expecting that it is now fixed.
I can't imagine why anyone would think cutting the Sensor Ground wire was a good idea!!! If you are having this problem hope it helps.