i got this 06' sporster.use to run great till recently. Engine sounds good but when i pull on throttle it doesnt have the punch it use to. I can no longer run past 70mph. When the bike is cold and I take off from idle it bogs out and almost dies. There is throttle response lag. If you need more description please let me know If this is in the wrong forum mods please move it. Thanks

 

You have ruled out bad gas I'm sure but if not I would do that first. If thats fine would look at carb. Could have some valves not seating or something internally but most likley in the carb. I would pull and give a good cleaning. Pull needle,jets make sure no trash in there. For some reason its not getting enough fuel it sounds like. Check for intake leaks between carb and intake manafold. Have not fooled with a Sportie but assume they have a rubber boot that the carb fits in like Big Twin does. Make sure its not sucking air there. You can spray some WD40 around the back of carb to see if idle rpm changes. If it does you have a leak.

 

My friends 06 883L ran like you described from the day she bought it new. It was running too lean because HD sets them lean to meen EPA rules. Had it re-jetted and it improved some, but when hot, it still had some hesitation. Last week, I installed the SE intake and breather. Seems to be running perfect now.

 

I would check the jets, my brother had the same problem replaced the jets and it was gone.