Author Topic: Fast Idle Question  (Read 472 times)

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Offline PJultra

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Fast Idle Question
« on: May 20, 2020, 06:49:56 PM »
I have a CV carb that I rejetted and the bike is running better then it has since I've owned it. I have just replaced the stock exhaust with a Rinehart 2into1.
What, other then maybe a choke issue, would cause the idle speed to run high and then go down to normal idle?
When I got off of the freeway and stopped at the first light, the idle was at around 1400rpm, I pushed on the choke which seemed to be all the way in, and after a few seconds it went down to 1000rpm. Then at the next light it happened again. I blipped the throttle a couple of times and it went back down.
It didn't do it on the way into work that I noticed.
First real ride since I rejetted.
No motor work done. Stock 80", ev13 cam, ness bigsucker air box, and the 2into1's.
Any suggestions? Thanx in advance,

Offline Burnout

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Re: Fast Idle Question
« Reply #1 on: May 20, 2020, 07:03:35 PM »
points ignition?
They don't call me Ironhead Rick just because I'm "hard headed"

Offline PJultra

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Re: Fast Idle Question
« Reply #2 on: May 20, 2020, 09:37:06 PM »
What is that, Dyna S dual fire with weights.
 

Offline Julio

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Re: Fast Idle Question
« Reply #3 on: May 21, 2020, 03:56:51 AM »
Idle mixture is too lean. Turn out the slow jet screw until it returns to idle immediately after you blip the throttle.
If turning the screw doesn't give you results, install the next bigger slow jet.

Offline PJultra

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Re: Fast Idle Question
« Reply #4 on: May 21, 2020, 07:02:05 AM »
Thank you. Right now the jets are 48/180. I will check that out.

Offline Hossamania

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Re: Fast Idle Question
« Reply #5 on: May 21, 2020, 07:11:45 AM »
A 48 seems a little large for an 80" motor. I don't think I'd go any larger, and would actually go with a 45 or 46. For reference, I run a 46 on a 95" with a cv44 carb.
Check for vacuum leaks first.
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Offline Racepres

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Re: Fast Idle Question
« Reply #6 on: May 21, 2020, 07:38:40 AM »
I had that with an Intake leak once also...

Offline Hossamania

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Re: Fast Idle Question
« Reply #7 on: May 21, 2020, 07:51:18 AM »
An intake leak may also cause false readings resulting in an overly large jet to overcome a lean condition.
When borrowing money from a friend, decide which you need most.

Offline Julio

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Re: Fast Idle Question
« Reply #8 on: May 21, 2020, 08:59:29 AM »
I've been running 48/175 jets on 2 stock early evos and an '81 shovel for years. I get ~42 mpg and all 3 start within 2 kicks when cold.
Before you start chasing vacuum leaks, open your slow jet 1/2 turn at a time and see if that makes a difference.

Offline JW113

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Re: Fast Idle Question
« Reply #9 on: May 21, 2020, 08:59:36 AM »
When is the last time you had the intake manifold off the heads? Those intake seals are notorious for getting brittle with age/heat and cracking.

-JW
2004 FLHRS   1977 FLH Shovelhead  1992 FLSTC
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Offline PJultra

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Re: Fast Idle Question
« Reply #10 on: May 21, 2020, 05:52:57 PM »
When is the last time you had the intake manifold off the heads? Those intake seals are notorious for getting brittle with age/heat and cracking.

-JW

It's only been a few months. I picked up the thicker blue seals. I have sprayed the manifold with carb cleaner and my idle doesn't change one iota. So I know I do not have a leak.
I will make little adjustments to the air mixture screw. If need be, I'll put the 45 back in.
That reminds me, I ordered new air mixture screw packing from CV Performance weeks ago. I haven't heard anything back from them

Offline Burnout

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Re: Fast Idle Question
« Reply #11 on: May 21, 2020, 08:23:19 PM »
Advance mechanism is borked and slow to return to idle.

(broken spring?)(or worse)
They don't call me Ironhead Rick just because I'm "hard headed"

Offline Racepres

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Re: Fast Idle Question
« Reply #12 on: May 22, 2020, 05:05:41 AM »
Advance mechanism is borked and slow to return to idle.

(broken spring?)(or worse)

On Older stuff...that used a mechanical Advance Mechanism... my go-to as well... But...OP says Stock 80 inch Evo... stock is Cup Pickup!!

Offline rigidthumper

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Re: Fast Idle Question
« Reply #13 on: May 22, 2020, 05:27:47 AM »
What is that, Dyna S dual fire with weights.
 
Check/lube the weight springs.
Ignorance is bliss, and accuracy expensive. How much of either can you afford?

Offline Racepres

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Re: Fast Idle Question
« Reply #14 on: May 22, 2020, 05:45:52 AM »
What is that, Dyna S dual fire with weights.

Apologies Burnout... You nailed it... I only read "Stock" and was silly enough to Assume we were talking about Stock.

Offline Burnout

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Re: Fast Idle Question
« Reply #15 on: May 22, 2020, 08:08:04 AM »
My most NOT favorite ignition!

This failure was in part caused by a Dyna S ignition.
They don't call me Ironhead Rick just because I'm "hard headed"

Offline Racepres

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Re: Fast Idle Question
« Reply #16 on: May 22, 2020, 07:43:12 PM »
My most NOT favorite ignition!

This failure was in part caused by a Dyna S ignition.


Damn Shame... But... I have had Much very good luck with the Dyna-S
Street bikes and On the Strip... on the strip we disable the Mechanical advance... locked down at full advance...turn ignition On after engine Spinning... Sorry you had problems... Looks like a Timing or...RPM problem... the Dyna-S as you know, does Not control RPM!!!

Offline PJultra

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Re: Fast Idle Question
« Reply #17 on: May 22, 2020, 07:56:02 PM »
What is that, Dyna S dual fire with weights.
 
Check/lube the weight springs.

My stock WAAAS EFI

Offline PJultra

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Re: Fast Idle Question
« Reply #18 on: May 22, 2020, 07:59:14 PM »
I've been running 48/175 jets on 2 stock early evos and an '81 shovel for years. I get ~42 mpg and all 3 start within 2 kicks when cold.
Before you start chasing vacuum leaks, open your slow jet 1/2 turn at a time and see if that makes a difference.

I have a 170 and a 180. I should pick up a 175 and give it a try. pretty easy since I don't pull the carb.

Offline PJultra

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Re: Fast Idle Question
« Reply #19 on: May 22, 2020, 08:01:09 PM »
Advance mechanism is borked and slow to return to idle.

(broken spring?)(or worse)

I will definitely take a look.

Offline PJultra

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Re: Fast Idle Question
« Reply #20 on: May 22, 2020, 08:06:57 PM »
What is that, Dyna S dual fire with weights.
 
Check/lube the weight springs.

Cuz there's better then lubed springs..... :SM:   hahaha  I get yer meaning. I'm just a true blooded smartass.

Offline PJultra

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Re: Fast Idle Question
« Reply #21 on: May 23, 2020, 09:41:49 AM »
My most NOT favorite ignition!

This failure was in part caused by a Dyna S ignition.


Can I ask, how did the ignition cause that? What happened?
I ran the same iggy on my shovelhead for years and never had a problem.
What iggy do you prefer?

Offline Burnout

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Re: Fast Idle Question
« Reply #22 on: May 23, 2020, 06:11:28 PM »
It was a single fire Dyna S, that unit has two sensors one for the front and one for the rear. The rear one failed, it went un-noticed as there were multiple problems. Got the other problems fixed and took it out for a test blast, and the random sparks nuked the rear piston.
They don't call me Ironhead Rick just because I'm "hard headed"

Offline Racepres

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Re: Fast Idle Question
« Reply #23 on: May 23, 2020, 06:39:47 PM »
It was a single fire Dyna S, that unit has two sensors one for the front and one for the rear. The rear one failed, it went un-noticed as there were multiple problems. Got the other problems fixed and took it out for a test blast, and the random sparks nuked the rear piston.
Someone didn't notice it was "One Lunging"

Offline Burnout

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Re: Fast Idle Question
« Reply #24 on: May 24, 2020, 09:47:28 AM »
It ran fairly decent, started well, like I said there were other problems that masked the problem with the ignition.

The other problems got fixed and he was enjoying the power improvement, when it belched out a significant fireball.    :bike:
They don't call me Ironhead Rick just because I'm "hard headed"