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FLST Idle Speed Question

12K views 12 replies 8 participants last post by  Kainam 
#1 ·
I have a 2014 FLST (103, fuel injected) that idles relatively fast - about 1050 to 1100 rpm.

The idle speed is too high IMO, however the dealer refuses to set the speed any lower. I have asked several times, and get a variety of reasons that all sound a little thin:

- the idle speed has to be high to provide sufficient oil pressure
- the idle speed has to be high to generate sufficient voltage to keep the engine running
- the idle speed has to be high, since the fuel injection does not provide sufficient pressure to run at lower idle speeds
- the idle speed has to be high, since the engine will not respond / run at lower idle speeds
- the idle speed has to be high.... etc.

My suspicion is that the mechanic does not know how to set the idle speed lower, so is coming up with excuses.

There are a number of web postings that show the same year and model softail idling at a normal speed.

I am confused by the excuses, and lack of any real information. Does anyone know if any of this is true?
 
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#2 ·
Hello,

It is always a good idea to introduce yourself first and tell us about yourself. People will respond much better to your questions. There are so many people that get on this forum and ask one question and do not even stick around for the answer. You will find tremendous help from people with a lot of knowledge here on this forum. My name is Jeff and I live near Reading, PA and drive a Sportster.
Do not mean to be up front and blunt with you, or high jack your post. It is just some guidelines we go by here. Lots of good people.

Thanks, Jeff Ludwig
:bikerguy:
 
#3 ·
1050 is the right idle speed for a fuel injected Harley. Going lower will cause lack of oil lubrication because of low oil pressure. Also will not put out enough voltage to maintain battery. lights, fuel pump, and other electronics will draw the battery down.
 
#8 ·
Thank you for the response, however I am still confused.



Please forgive the questions, but I am trying to understand. The manual gives no information that would help with this.

The reasons you stated support what I have heard, however it still does not really make sense to me.

The oil pump is a positive displacement trochoidal type used in automobiles and motorcycles for years. They push a volume of oil per revolution. The distribution of oil should work even at very low speeds unless the bearing tolerances are extremely loose and oil is leaking around them.
When we used to rebuild engines, before we put on the cylinders, we would hook up the oil fed, grab the rods and spin the engine over until we could see oil coming out between the rods. It did not take much, and a significant amount of oil would come out.

As for the alternator, I do understand that running at very low idle speeds could reduce the output, but that is why there is a battery. Is the electrical demand really so high that idling for a few minutes would kill the battery? What is using all of that power? The EFI system?
 
#9 ·
From memory ... the big twin TC engines have an adjustable idle RPM of 950 - 1150 RPM. The RPM is adjusted electronically using the shop computer, no screws to turn.
The low oil pressure and supplied voltage are some of the reasons for the higher idle RPM. EITMS, if equipped, plays into the equation. No potato, potato, potato with the EFI TC engines ! Sorry !
The OP's 2014 Softail can be adjusted down to 950 RPM but still no potato, potato, potato !
My suggestion is for the OP to leave his engine idle at the optimum 1050 RPM.
 
#10 ·
As far as the question about the alternator, the alternator puts out amps and volts always. The regulator cuts in and out when it senses low battery charge. The regulator is the boss !
The electrical system taps off the battery until the regulator senses low battery volts then starts sending amps to the battery. If the engine RPM is lower than normal the regulator can't supply the battery quick enough and the battery discharges.
Hope this info helps.
 
#11 ·
What SCHMITDYS said.... Depending where you are in Kalifornia, when summer heat hits. Engine heat will thin oil. Higher idle speed will push more oil for cooling. Yes it a positive displacement pump. Need a certain amount of RPM's to push volume @ pressure down the line. Engine bearings require specific oil pressure to run properly when under a load while running. Spinning engine with starter will just lube engine parts prevent a dry start. Ride Safe.
 
#13 ·
The only high oil pressure part on a TC motor is the piston oilers, the tappets, and rocker bushings. And in the case of 2007 (+ 2006 Dyna) and newer, the outer cam bushing. Everything else is more oil flow and low oil pressure.

Harleys do not use high oil pressure Babbitt bearings as are used in automobile engines.
 
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