Most people don't let there bikes idle for more than a few min anyway. So unless you let it idle for 15 or 20 mins at a time, doesn't seem like you have much to worry about.

 

Yikes...I just checked the price of the TTS MasterTune....pricey mod for a lumpy sub 1k idle.

I have an 06 Dyna, FI twin cam 88.
Correct me if I'm wrong, but the 05 Dyna with the twin cam 88 was carb'd, right" Yet..the rest of the engine was the same, oil delivery system and all? And those, by default, idle lower, correct? If the above is true...I don't get the "you'll starve your engine of oil" arguement. //scratches head

I'd love to get mine down to 860 or 900 or so, but I ain't swinging 400 plus bucks for that TTS setup.

 

I found a difference of .8 volts between 802 and 2400 RPM. 13.1 volts at 802 rpm, plenty.

 

I'll throw out another theory for the higher idle. Harley's FI is speed density so it depends on a MAP sensor. I would imagine that low idle potato sound would also produce a pretty irratic vacuum reading.

 

Nobody I know buys the TTS unit just to get the idle down. There are plenty of threads on here with info related to the performance benefits of this unit and the versatility it has for engine modifications. Its without a doubt the best mod I've made for my EFI bike and would be the first I make to any new bike in the future if it is still available.

BTW... I've been running 950 RPM on my 08 EFI TCB for about 21000 miles now.

 

Subscribing. This is a great read. As I'm considering HD#3 but the new bikes that's the one thing I hate, the honda-esque fast idle that makes me miss my 90 heritage with duals. And that first opening post was probably one of the best openers I've read, ever! Well put Sir.

 

Anyone else wishing to subscribe could do so through the use of the thread tools at the top of the page. I found and used it, but after all these subscribed remarks I thought I would remind that the ability is there! Jus sayin!
My$0.02

aka Bob

 

There is a cap to the output, as the voltage regulator dumps excess voltage as heat. Sounds like yours is set to dump at 13.9 volts.

Generally speaking, optimal charge voltage in a motorcycle is in the 13.5 to 14.5 volt range. 13.1 is too low, though it probably won't result in a discharged battery.

In my case, I've had two bikes where the alternator's output at idle was right at or around 13.5 volts and any additional load would drop it, including a turn signal. On my current Monster the turn signal drops it by ~0.2 volts, and the high beam lamp drops it by ~0.8 volts. So just idling with the high beam drops me to 12.7 volts, which isn't enough to charge the battery. Any additional load would drain it at idle.

Which is exactly what happened on my previous Ducati which was water cooled and therefore had a cooling fan. Sitting in traffic for a couple of hours resulted in the battery draining so much that it could no longer supplement the alternator's output enough to handle the total electrical load, so my bike died. Ironically, if I'd idled the engine faster, it would have had enough alternator output to keep running the cooling fan to get me home.

It is best that idle never be set lower than whatever setting gives you a 13.5 volt output from the alternator. Start plugging in accessories and you can very well drain your battery when sitting in traffic.

 

My warm idle on my 07 is about 900rpms all the time with a dip lower here and there. All it has is XIEDS/SE a/c and cfr slip-on's w/fullsac mod.

At times I have seen it dip to mid 800's. It most certainly gets more of a lope to it.

weird.

 

I've got a FI 2002 Deuce, stock except for stage 1.

I have 25000 miles on it now, and have been running an 800 rpm idle on it since it was at 5000 miles. I've never had any problems with it.

A tech can set or adjust the FI idle speed (at least on 2002 Softail models) anywhere from 800 to 1200 rpm using the Scanalyzer.

Mine was factory set at 1000 rpm until I had it adjusted to 800 (which is as low as it will set) 20,000 miles ago.

I've had no issues with it. No dimming of lights at low idle, no low oil pressure lights, no unusual or excessive engine or valve noises, etc. It seems to be fine.

I would think that if there was any real danger to it, the computer wouldn't allow it to be adjusted under 1000 rpm. As it stands, the computer limits it to an 800 rpm minimum, and their must be a reason why the designers chose that number for a lower tuning limit. (It still idles well, and isn't close to stalling, etc.)