[sivan]

This is an issue that we frequently see brought up: why does it idle higher after a long, fast ride? I'm pretty used to the phenomena myself not to make a fuss out of it, but lately it's been a little too much to ignore. Yesterday I came into the city from the freeway with idle at 2500, and combined with the hot weather and traffic jams, found myself forced to turn off the engine at stop lights before it shoots close to max temperature.

The factor of coming down from revving high for a while is familiar, but I can't resolve the correlation between high temperature and high idle as they appear to reinforce each other. Earlier yesterday, I was doing some parking lot drills (MSF exp.), not revving high, but the hot weather apparently shot my idle high as well throughout the day, again reinforcing high engine temperature and so on. I'm a little alarmed that this phenomena can actually get to a point of being forced to shut down. The bike runs great otherwise (jetted, K&N) and has enough oil. Any ideas?

 

[mspgs2]

Well there is a relation between RPM and temp and at higher rpm with less airflow you are going to run hotter. The pistons have little fireballs on top of them and the more fire, the more heat.

What kind of temps are we talking here? 230? 250? more?
Whats your idle rpm at after coming to a complete stop for a few seconds? Possible the ECU isnt reading the environment correctly if this is a FI bike.. or is this a carb'd bike?

 

[sivan]

This is a carb'd bike, 250F

 

[mspgs2]

hrm that is odd.

Is the throttle completely closed (cable not kinked or stretched)?
Can you reachdown and manually work the linkage and its definatly closed?
Maybe something in the carb is heating up and sticking open?
Fuel leaking into carb?

 

[sivan]

Well I spoke to my shop and they recommended adjusting the idle a bit lower on hot days. They also confirmed that high temperature and high idle basically reinforce one another.

 

[javadave75]

I have a question about this topic. I seem to have a high idle that revs high when I come to a stop and rolls down a bit after 4 secs or so. This doesn

 

[sivan]

It's normal for it to be high a minute or so after coming to a stop from riding at a high RPM for a while, whacking the throttle for a second sometimes takes care of it. From what I understand the carbs float bowels are flooded and it takes a bit to adjust again. In my case, it just wouldn't come down after reaching high temperatures. I couldn't understand the theory exactly, something about the high temps making it too lean and that somehow pushes the idle up.