Why an idle cable?

Reply Subscribe

Thread Tools

Search this Thread

Jun 28, 2018 | 07:49 AM

The Twigster

Thread Starter

Advanced

Joined: Jun 2012

Posts: 54

Likes: 1

From: Deming, NM

Why an idle cable?

So......on my '08 Dyna I snapped the idle cable tube at the adjusting nut and ordered a new one. While installing the new one I question as to even needing one. Someone correct me if I've missed something. Since the butterfly opens with the throttle cable and closes because it is spring loaded, what does the idle cable do? The idle is set by the computer so there's no adjustment needed for that like on the old carbs. So right now I'm riding with only the throttle cable and don't see any difference.

Jun 28, 2018 | 07:51 AM

SixDD

Banned

Joined: Jan 2014

Posts: 8,688

Likes: 1,902

From: Depends on who wants to know.........and why.

Great question. ***subscribed***

Jun 28, 2018 | 08:09 AM

MURPHCC1

Club Member

Joined: Apr 2013

Posts: 5,760

Likes: 3,756

From: Cape Cod

The butterfly valve spring is not strong enough to make the whole thing return.
There is NO designated return spring (Like a car) so the idle cable is mechanical advantage to return to idle. Great safety feature as far as Im concerned......back in the day a broken return spring would most times result in a full throttle run.....NOT GOOD!!!

Jun 28, 2018 | 08:11 AM

archergodwin

Elite HDF Member

Joined: Sep 2008

Posts: 4,440

Likes: 148

From: Northwest

It's a safety thing thought up by someone who probably isn't a rider. The thought is, if your throttle cable broke while going down the road, or a WOT, you can 'pull' the throttle closed with the other cable.

It probably happened once.. or twice maybe... and some bureaucrat somewhere 'had a mission' to save us all.

Jun 28, 2018 | 08:25 AM

The Twigster

Thread Starter

Advanced

Joined: Jun 2012

Posts: 54

Likes: 1

From: Deming, NM

Yah, I thought of that too but the kill button would over ride runaways.

Jun 28, 2018 | 11:35 AM

JohnMn

Outstanding HDF Member

Joined: Sep 2014

Posts: 2,717

Likes: 273

From: Minnesota

Quote:

Originally Posted by The Twigster

Yah, I thought of that too but the kill button would over ride runaways.

Sure,, but only after the few seconds pause of awareness and action that is the human condition of brain and muscle. A lot can happen in 1.7 seconds at WOT in traffic,, that an already conditioned wrist twist of throttle response could avoid.
As already said,, the second "idle" cable was added as another safety feature along with the changes in throttle body of EFI, lighter springs and ECM engines.
HD is not the only one with this now decades old advancement in control.