I bought a XL1200N from a guy, who had won it in a contest. It had 27 miles on it when I trailered it home. It would idle erratically and when you would just barely crack the throttle the bike would kind of jerk gently when I was going at slow speeds obviously this would be more pronounced in the higher gears at slow speeds. No mods on the bike whatsoever. I put Rush slip ons on it the other day using all new gaskets( the bike now has 1900 miles ) and it runs like a scalded dog. Still no other mods. However it is still idling erratically and running exactly the same at low speed with the throttle just barely cracked. I can crack the throttle just a little more and it will smooth out and run just great. I talked to a Harley mechanic, who now works for a Kawasaki Dealership and he suggested it might have an intake leak. I su****ion that the map is screwed up from the day it left the factory. What can any of you fellows add or correct me on my theory.

 

Is this your first bike? I only ask because it sounds like maybe you are just lugging the engine at slow speeds. And the irratic idle could just be that old potato potato sound if you aren't used to it. If I'm way off base here then I'm sorry. Little more info I guess.

 

Need more info than that, like just when cold? all the time? just when hot? how erratically?, just at low RPM?
Remember that the sportster engine needs much higher RPM than a big twin, especially with fuel injection, don't be afraid to rev it and keep the RPM high in all gears, do not lug a sportster engine like the big twin guys do. Factory set up is very lean and that makes it very jumpy, since I got my PC5 my engine is much more mellow and predictable (at the cost of a tiny bit of raw power I might add).

 

+1. Sporty's don't like to go slow from my experience. Its prob because your RPMs are too low and its almost lugging. Get the RPMs higher and if you're going at really slow speeds in 1st gear, make sure you feather the clutch...it helps.

 

Sorry about the info, the erratic running is when there is no load, when it is basically coasting in gear on level stretches with the throttle just barely cracked. If you start up a hill then it will settle into a smooth lug. this is not my first bike. I am sixty three years old and road British Twins for years. I have a Roadstar which runs smooth almost to a stop. I don't lug the Harley because when ever it gets down to the fast idle I have to gear down to stop the slight erratic running. I have wondered if it might be the idle control unit. By the way this is a 2008 model.

 

Several people (including me) have had surging problems with EFI bikes that
are distinctly NOT BEING LUGGED. The problem is real, it exists and it has a
real effect on low speed operation. Nonetheless, the answers you are going
to get are "ride it like you stole it", "they all do it", "you're lugging it",
"it's a Harley, get over it".

Mine is now much better (it almost never does it) and I don't know if that was
the result of an ECM reflash that was done or it just settled in on its own.
See this thread..
https://www.hdforums.com/forum/sport...h-for-efi.html

Good luck getting worthwhile answers..

 

I take it this just started when you changed the pipes or has it been this way since the start?
Might be worth running some seafoam thru it and checking for intake leaks with WD40 while it' idling.

 

If I remember correctly some of the 2008 had a fuel pump issue (not with the pump but with a fuel line connection in the tank)

 

Thanks men, to answer Hotlaps question it has been doing this since day one even with the stock pipes. The Rush pipes seem to give more power its just that now its louder so you can hear the erratic idle and slow speed better then with the stock pipes. the feel is the same. This morning when I rode it to work I checked the oil temp by sticking my finger in the oil tank and I've taken baths in water that was hotter then the oil so I don't think its running hot.

 

If the fuel line is the problem what is the recommended fix. the bike is still under warranty but the Dealer closest to me is still thirty five miles away through all kinds of idiot traffic, rather fix it myself.