New to the forum, have gained a lot of information regarding this common issue.
I recently picked up this 06 XB12X. I purchased knowing it didn't run.
1) it would turn over just won't start.
No codes on ECM
Checked and cleaned injectors
Fuel pressure checked by dealer OK
Used ECM DROID to check coil output to
plugs Ok
Tried new ECM
No change
I then had an idea that the ECM didn't know the engine was turning. I then checked the 5 volt ECM output for the cam position sensor. It was at 0 volts. While going over the wiring notice ECM was warm to the touch . I disconnected each sensor one at a time. When I got to the speed sensor the 5 volt signal was present. The bike started! The 5 volt wire was shorted to engine case. Replaced sensor, I did and didn't make sure the cover didn't pinch the wires. After 8 mile the speedometer syopped working. This time the sensor output was grounded. But the bike ran great, just speedometer didn't work. Fixed the short and rode back an forth to work no issues for a week. Took a ride to the dealer then to the mountains. At 73 miles the bike started this missing and studdering. Stopped at gas station to checked fuel level OK . Started back up ran fine until after about 7miles. Back to running poorly agian.headed home, some times clearing it self on the way. NOTE: the tach does not jump and Thier were no stored codes.
Now it's constantly missing. I have cleaned the grounds added the ground to the coil mount moved the battery ground so all ground wires are directly connected to battery. I have checked for intake leaks none found. While checking grounds again the ECM sensor ground pin to ground was reading about 13 Megs.
Disconnected the speedometer sensor because it was close and it went to 0 ohm. Another note: speedometer needle not jumping around. Seems to be operating normally.
So onto the question, could this be the cause of the missfire and studdering?

Thanks everyone for the information I have used so far.