Hanging Idle Definition?

[BigD_83]

I know that a hanging idle is kind of self-explanatory, but I found myself in the garage tonight, adjusting the fuel mixture screws, and wondering whether there is an accepted definition of hanging idle.

I'm trying to get a sense for what is normal with these GSes.

How long must the rpms remain elevated when one closes the throttle to be considered a hanging idle, say closing the throttle down from 4500 rpm?

Is 3 seconds too long? 1 second? Any hesitation at all?

In my case the rpms start to drop with little hesitation when I roll off the throttle, but it takes approximately 1/2 sec to get back to idle (~1100 rpm). I can't say what it does under load as I haven't been able to take it out on the street since I started tearing into the engine.

[Nessism]

I don't know what the answer is but I do know that the intake pipe boot O-rings fail at an alarming rate and should be changed as a part of normal maintenance. These O-rings are the number one cause of the common hanging idle issue so don't wait for the problem to occur, eliminate the possibility though maintenance.

[BigD_83]

Thanks, Ed.

Some of the terms that get thrown out there can be a little confusing. Just like anything esoteric and technical, it's tough to communicate a problem if everyone is not on the same page with understanding of terms.

I'm not having an issue as I've gone through the "Top 10" rigorously. The carbs and intake O-rings were the first things I addressed. I know I've read some people saying they get over 30 seconds, or even a constant hangup. I'm definitely not seeing anything along those lines.

[ChicagoBob]

I'd say that any hang is a problem. GS engines are known for their snappy response, like most engines with light flywheels. The engine should drop immediately to idle when you chop the throttle. When you want to stop quickly, or are riding downhill, even two seconds would seem too long.

[Steve]

I would say that your half-second is about right.

A quick jetting check can be done by judging the engine's response to cutting the throttle.
If it 'hangs' and falls slowly, it's running lean.
If it falls quickly, but goes below the idle setpoint and comes back up, it's running rich.
If it falls quickly and settles in at the idle setpoint, it's just right.

These checks are for the PILOT circuit only, they have NOTHING to do with the main jets or the needles.

.

[BigD_83]

I would say that your half-second is about right.

A quick jetting check can be done by judging the engine's response to cutting the throttle.
If it 'hangs' and falls slowly, it's running lean.
If it falls quickly, but goes below the idle setpoint and comes back up, it's running rich.
If it falls quickly and settles in at the idle setpoint, it's just right.

These checks are for the PILOT circuit only, they have NOTHING to do with the main jets or the needles.

.

Thanks, Steve,

I've never seen that kind of guideline in print, but it makes perfect sense to me and pulls together a bunch of ideas into one place.

Derrick