engine revving problem

[kirkmc52]

when my 1200 nightster xl is driven on the freeway for longer than
40 minutes (approx), and the throttle is released to slow down and or stop- the engine stays revved up for 30-50seconds before idling to the speed im traveling or to the nuetral rest if the bike is stopped. Its got 7,600 miles has been in for all its services prior to the problem starting, since it has started ive taken it in had it hooked to a computer and the cables checked. The cables were fine and no error codes came up. i have since checked with two other hd service departments and none of the techs had any idea what is causing this. Any ideas?

 

[Hoople]

What year bike. Carb or injected.

 

[kirkmc52]

09-injection

 

[Hoople]

You may not have a tach, but how much reved up would you say. By a lot?

 

[HDDon]

Have you done any mods to the motor? What is the last thing you added or took off the bike? Did this start all of a sudden or did the engine slowly creep up?

 

[kirkmc52]

no i dont have a tach. i have not made any engine mods or any other major changes to the bike. if i was traveling at 70mph and stop there is no change in the engine revv at all, the engine still sounds and acts as if its at 70 . it started doing it sporadic then became evertime i travel on the freeway longer than 40 minutes

 

[HDDon]

Have you tried cleaning the IAC?http://www.hdtimeline.com/archive/t-18936.html

 

[Hoople]

if i was traveling at 70mph and stop there is no change in the engine revv at all, the engine still sounds and acts as if its at 70 .

70 MPH in 5th gear has to be 2750 RPM. That is a bunch. So when you stop, the engine is racing at maybe 2700 RPM. If the IAC was wide open, you may be able to supply enough air to do that.
Both the pull and push throttle cables are still factory stock? If so, I would start with the IAC like HDDon suggested. See if flushing makes it better. You may have to pull it out and really clean the stem.

 

[kirkmc52]

I cleaned out the IAC and rechecked my throttle cables, went out for a ride yesterday and it seemed to fix the problem.
Thanks alot!

 

[HDDon]

Glad your back to running. Keep us posted if the problem comes back.