Be kind I'm an Old fart and old School.  My bike is a 1200 xl c 2013/2014 got new from a Sydney dealer, with First stage kit. slipons,air fillter and tuner fitted, all S/E. Problem. First time about 30 months ago. it happened I was slowing down after a good run, at lights. The revs just started biulding (mear 2500) up with no action by me on the twist grip. As I was going past the dealer on the way home I just was very easey driving there ( high gear no action on throttle). About 300meters before dealer the bike went back to normal ?? Still went into dealer but they found no "error code"  so there was no problem ??  Same problem 1 week later, at lights but after setting off from lights problem went. Then all ok for the next 28/29 months or so. Now for the last 5/6 weeks the problem is back. I ride with the Old Farts club midweek. so we have morning smoko after about 1hr ride when the bike is OK. then on setting off after smoko within 2/3 km the reving problem starts again, about the same each week with only one week with no problem. It was a longer smoko that week. I did take the bike to another dealer whom did warm the bike up before working on it. But again "not error code no problem"  The 4/5 weeks I rode with the problem riding very slow under 60k/h in 5th gear the problem went, but was back within that same 2/3 km. Hope a techo can put me on the right track, If you say a sencer ABC  or  XYZ  it my go over my head , so be kind we all grow old. Thank in advance for any answers.   And no cannot find a sticking butterfly valve at airfillter. Old Sandy.      

Hey mate,

Very common problem with EFI sporties, the IAC valve is most likely the culprit.

Stuff you can check in the meantime, the push/pull portion of the throttle is smooth, the little knob at the bottom of the throttle is not done up.

My reccomendation is to spray some MAF cleaner (Mass airflow meter) made by CRC into the IAC hole. If it is dirty/gummed up it will do as you are describing.

The IAC's can also fail, it's not an expensive part and can be replaced by the average home mechanic with the manual.

Besides the IAC and the stupid riveted clutch plate, EFI sporties are absolutely bombproof.

Hope it helps.

i agree with brash, might did it too, on mine it was the IAC, i tried the cleaning, but it didn`t really help for long, i ditched it last year and made an adjustable screw needle instead, it works well other than in winter you need to hold the throttle open alittle for the first 2 minutes, or continually adjust the needle.. they are for sale on ebay i think, called manual IAC, lets you bring the idle speed down alittle lower too.

http://xlforum.net/ this is a great american sportster forum, search and chat some on there old sandy. good luck (((-;

Thanks to All for a Quick answers. will try to work my way through one by one. Old Sandy.

start with the AC and TPS...About $50 each

And start going to a different bike shop. If these guys here on the forum know this, ask yourself why experienced, trained mechanics don't know and don't have the intelligence to ask someone more experienced or research the problem.

Hi lucifer_mr2. old sandy here. Maybe you are one of the very few to have this problem, and has corrected it. Were is the TPS sensor as regard to the IAC . Did you or a Stealer "Dealer" find it. can it be found (tested) with a multi-meater or just by looking at it. Was it nice and eacy to change. I have time on my hands so could a guy that can use a spanner or a Multi- meater do the job. Any help, tricks, or things to do or not to do would help. Thanks in advance. Old Sandy. And a Picture would be good. I hope my lucks in on that one.

Hi punkin. Old sandy here. Yes I did ask myself all you put in your message, but I did NOT get a good aswer to myself. So I got on the XL forum and going by the number of US guys with this problem it would make a lot of dealers uncarring about their bread and butter customers. so if there is a one off answer it would be out there by now I think this bike being air cooled with so many sensors that cross loop back and to, to the ECM that any one less than 100% makes problems. Even Air temp as over here in Oz and to say nothing of petrol quality. I think it would take a mass legal action for HD to correct this problem. Anyway thanks for your input. Old Sandy.  

Just basic fault finding would be great at a dealer.. which comes down to experience..

And the outcome was?