Fast idle duration?

How long should the fast idle last in average, before the bike switching to the "regular" idle? How long does yours do it?

My FJR does that less than a minute. The heat meter sometimes doesn't flinch, sometimes I barely get to one bar in the LCD. Is that normal, or should it last longer, starting from completely cold engine?

Background: Due to botched repair shop work, my FJR was recently driven a few miles (started many times) without coolant being routed through the fast idle. I am wondering if that could have done something to the fast idle. Having read how the fast idle works, I think it should not have caused any damage: the fast idle system probably just stayed always on since there was no heat (from warmed-up coolant) to melt the wax inside. Thought it not a bad idea to get a second opinion though.

1.5 min. Maybe 2 min.

If the bike isn't too cold and if the ambient temperature is 20 °C or higher, the elevated RPM for the cold idle only lasts a minute or so. The system is a little different on the Gen I bikes (I think the cold idle is a little higher RPM). They dropped the cold idle speed to accommodate the needs of the AE version on the Gen II. I doubt that running without coolant going through would cause any harm! (Might need a clean and adjustment as per the following...

Look here

https://www.fjrforum.com/forum//index.php/topic/122016-further-details-on-fast-idle-system/?p=643206

and

https://www.fjrforum.com/forum//index.php/topic/121060-fast-idle-unit-on-throttle-bodies/?hl=%2Bcold+%2Bidle

The pictures are hosted by Photobucket but if you use Chrome with the Photobucket fix extension, you can see them...

https://www.fjrforum.com/forum//index.php/topic/172794-photobucket-fix-for-chrome-and-vivaldi-web-browsers-and-now-firefox/

I'll hazard the assumption that contemporary motorcycles are subject to the same sort of emissions restrictions as cars are, and the fast idle time for automobile engines is limited by government regulation. This is mostly because the cold fast idle is also accompanied by enough mixture enrichment to keep the thing running until it warms up a little, same as an automatic choke used to work. The fast idle time will also be affected by ambient temperature; the warmer it is out, the less time it will run before settling down.

My '08 fast idles for about a minute most of the time.

Mine last maybe a minute, I wait for it to idle down before riding.

s.ga.rider said:

Mine last maybe a minute, I wait for it to idle down before riding.

Click to expand...

Why? I just start and go but don't hit the throttle hard until it is showing a bar or more. Never any issue with it balking when taking throttle input - unless it is REALLY cold.

With the elevated idle RPM, you do have to be a little more careful at low speed maneuvers. Might use a touch of brake sometimes where you wouldn't otherwise need it.