Hi
No fault codes are showing on the 2007 Harley XL 1200 it running lumpy this is the readings I’ve got on my 02 sensors 2940 rear and the front is reading 1080 and the front will go all the way down utill 400 when I try to throttle it and will stop the bike but the rear reading never goes that low is this showing a faulty front o2 sensor ?
Many Thanks Ben

 

While your front O2 sensor may be weak, if it's changing voltage with different conditions, it's working. Front might be running lean for a separate reason. Get some carb spray and spray it into the intake and see if that reading comes up to normal. If so, you need to find the vacuum leak or component causing the lack of fuel to that cylinder.