Idle rise


Information and questions on GL1500 Goldwings (1988-2000)
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dj norm
Posts: 17
Joined: Sat Mar 03, 2012 10:10 am
Location: Quebec, Quebec, Canada
Motorcycle: 1997 GL 1500 SE

Idle rise

Post by dj norm »



Hi I have a 97 Gl 1500.

I juste rebuilt the carbs , complete kit including OEM diaphragm all is fine except one thing.

Good start cold or hot runes and idle at 950 but ride for 5 minutes and rpm rise at 1100/1200 by it self if I shut it of 5 seconds and restart rpm is back down???? Help .

There is always a rise of approx 200 rpm its a pain for downshift, Is comes dow slowly and if I lower rpm once I shut off and restart it’s to low.

:roll: :roll: :roll: :roll:


Norm.
Arte et Marte

Graham B
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Joined: Wed Nov 07, 2012 3:59 pm
Location: Tenterden, England, United Kingdom
Motorcycle: GL1500SE

Re: Idle rise

Post by Graham B »

I had something similar and I lost count of the number of times I had the carbs out checking all the vacuum lines. We came to the conclusion that the bike was haunted.

It turns out I hadn't checked all the vacuum lines. This is a good number of years ago so I apologise if this is a bit vague, but, if you remove the carbs again (sorry), gently lift the heat protector mat and, between the manifolds, is a tiny vacuum balance pipe. Once I replaced this and reinstated everything, all was well with the world.

The old pipe had a tiny (And I mean tiny) pinhole.

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dingdong
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Motorcycle: 1976 gl1000
1993 gl1500A
2004 NRX1800 Rune SOLD

Re: Idle rise

Post by dingdong »

This is the line he is referring to.



Graham B
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Location: Tenterden, England, United Kingdom
Motorcycle: GL1500SE

Re: Idle rise

Post by Graham B »

That's it!

Thankyou.

gwjturner
Posts: 52
Joined: Mon Sep 04, 2017 4:16 pm
Location: Champaign, Illinois
Motorcycle: 2000 GL1500 SE

Re: Idle rise

Post by gwjturner »

Graham B wrote:
Tue Jun 16, 2020 7:33 am
I had something similar and I lost count of the number of times I had the carbs out checking all the vacuum lines. We came to the conclusion that the bike was haunted.

It turns out I hadn't checked all the vacuum lines. This is a good number of years ago so I apologise if this is a bit vague, but, if you remove the carbs again (sorry), gently lift the heat protector mat and, between the manifolds, is a tiny vacuum balance pipe. Once I replaced this and reinstated everything, all was well with the world.

The old pipe had a tiny (And I mean tiny) pinhole.

Wow! Is there ANY other way to get to that line?

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dj norm
Posts: 17
Joined: Sat Mar 03, 2012 10:10 am
Location: Quebec, Quebec, Canada
Motorcycle: 1997 GL 1500 SE

Re: Idle rise

Post by dj norm »

Thanks guys.

Forgot to write in my post but vacuum lines where replaced also .

Its bizarre because it runs fine just the idle rise by it self and if I just shut it off 5 seconds and restart without toutching anything it’s back to 950 .
Norm.
Arte et Marte

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ct1500
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Location: Glastonbury,CT
Motorcycle: 1988 GL1500
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Re: Idle rise

Post by ct1500 »

Why an idle speed of 950RPM when spec is 800 +/- 80, does it have another undesirable trait at spec? What happens to idle/running quality when it is set to 750RPM?
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dj norm
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Joined: Sat Mar 03, 2012 10:10 am
Location: Quebec, Quebec, Canada
Motorcycle: 1997 GL 1500 SE

Re: Idle rise

Post by dj norm »

Does not matter what I set it to it increases by approx 200 by it self also it’s slow to return to idle when shifting its bizzare. If I just shut it of an restart it’s back to low idle
Norm.
Arte et Marte

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thebruce
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Location: Boundary Country, British Columbia, Canada
Motorcycle: 1991 GL1500SE Anniversary Edition #54

Re: Idle rise

Post by thebruce »

Just to get this possibility off the table, are the throttle/idle cables set properly and correctly routed? Also does the throttle snap closed or do you have to help it a little?

It really does seem like an air leak, though.

I like to hunt down vacuum leaks with a can of brakleen. You will hear a definite change in idle when the brakleen finds its way into the leak. I have not yet found the air cleaner on my bike so am not sure of the feasibility of this method.

If you choose to spray a flammable/explosive solvent at a running engine use caution. Well ventilated environment with a fire extinguisher handy is a good place to start.
It doesn't matter what you ride, as long as you have your knees to the breeze.

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ct1500
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Re: Idle rise

Post by ct1500 »

When did the problem first appear and what other work was done since this started? Barring the obvious due to throttle linkage issues an area that might be checked is if the cruise control actuator/system is problematic (vacuum/linkage) when there should be zero vacuum and slack. A hanging shot air will keep the RPM up during shifting. Plug-cap/pinch off the green PAIR intake hose at bottom right front of air box then road test and see if problem subsides. Double check for correct Air Jet Controller vacuum hose routing (bottom ports #18) and that IAT sensor is plugged in at air box. :) Is this CA emission equipped?
Local and need repair help with your 1500, Valkyrie or ST please click contact
Nothing leaves my shop till its' perfect
This is what I do

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dingdong
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Motorcycle: 1976 gl1000
1993 gl1500A
2004 NRX1800 Rune SOLD

Re: Idle rise

Post by dingdong »

You didn't mention if you synced the carbs. Idle slow to return is a symptom of uneven sync.

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dj norm
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Location: Quebec, Quebec, Canada
Motorcycle: 1997 GL 1500 SE

Re: Idle rise

Post by dj norm »

I revised all my job and the problem was due to a bad idle mixture screw. Donne adjustment plus synchronization of carb now purrs.

Thanks


Norm.
Arte et Marte

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