Another Idle Speed Adjustment Question...

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Apr 20, 2014 | 09:26 PM

AAAC

Thread Starter

Tourer

Joined: Mar 2014

Posts: 326

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From: Idaho

Another Idle Speed Adjustment Question...

I just got through reading the other thread regarding idle speed adjustments and now I'm wondering about mine. I have a carburated '97 Road King. When I bought the bike and you started it up cold with the fuel enricher pulled out, it would idle at around 600 rpm until it warmed up then it would jump up to 1100 rpm...at which point you push the enricher in and it would drop back down to about 600 rpm. I bumped the cold idle up to about 800 rpm and my warm idle is about 925 rpm now. Is this still too low? The guy I bought it from said he liked the way it sounded at lower rpm but it's my understanding that this is not good for the engine. I figured I'd see what you guys thought about the matter...Thanks!

Apr 20, 2014 | 09:35 PM

johnjzjz

Seasoned HDF Member

Joined: Nov 2006

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From: la la land jerzey

if it idles to low the connecting rods chuckle and at some point will damage the rollers - this is not what you want leave it around 1000 RPMs and you wont have any issues

Apr 20, 2014 | 10:34 PM

amasoniii

Cruiser

Joined: Mar 2014

Posts: 125

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From: michigan

right, anything below 950 can give you oiling problems that lead to engine damage and can also cause charging problems. Change the pipes if it doesn't sound good at the proper idle.

Apr 20, 2014 | 11:20 PM

cowboy 51

Road Master

Joined: Nov 2012

Posts: 794

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From: Alvin TX

I know a lot say 1000 rpm Idle is perfect ,But I run 950 & no problem at all oil runs good & sounds good at idle ,I have a bit over 68k miles on my 94

Apr 21, 2014 | 11:35 AM

falconbrother

Road Master

Joined: Jan 2012

Posts: 856

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From: North Carolina

I had a Heritage with cams and all sorts of goodies. I left the idle where it was when I bought it which was low.. It sounded really cool but, I now know it wasn't very good for it. If I had it to do over I would turn it up a bit. On my 1988 EG the charging system isn't doing anything useful till about 1000 RPMs.

Apr 21, 2014 | 04:00 PM

grbrown

Club Member

Joined: Jun 2007

Posts: 45,429

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From: Bedford UK

There are various jolly good reasons for maintaining the book rpms, of which charging and oil pressure are two. However the main one is mechanical. If engine speed slows too much, the crank is accelerated when one cylinder fires, but slows as the other one reaches compression, then accelerates, slows, etc. That is where the damage John mentioned can come from. Book idle speed enables flywheel momentum to even things out, to prevent that cyclic crank speed.