I foul the front plug if I let it idle for a period of time. If I take the bike out and run it hard for 20 or 30 miles it seems to clean the plug up a little bit. The rear plug is still like chalk. I bought this 04 Road King with these upgrades. I got a good deal on the bike, that's the reason I bought the bike. The guy I bought the bike from didn't have much information about the motor. I have been searching serial #'s down trying to find out what kind of upgrades have been done to the engine. I have been experiencing this sense I bought it in March of 2014. was told that the engine has less than 5000 miles on the motor. The pistons and the heads look brand new like it's burning clean. The front plug is black and the rear plug is white. I have done a leak down test and got about 4 to 5% on the front and the rear cylinders. I have checked for intake leaks. I have also pulled both injectors and cleaned them with carb cleaner using a 9 volt battery. I have swapped the injectors and the O2 sensors to see if the problem followed the parts. I have tried to manually tune the Daytona twin tech TCFI and the the AFR on the front returns back to running rich and the rear to lean according to the live data log. I am not very savy with the Daytona Twin tech system. This is my first custom bike also with EFI. I had a Fat boy with carbs and it was no problem to tune.
Thanks,
Teddy Stevens
Sorry for the long reply. I hope that I give enough info.