Rev increase issue when Idle


Information and questions on GL1100 Goldwings (1980-1983)
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Trulylegend
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Joined: Tue Mar 30, 2021 3:22 pm
Location: Mesa, Arizona, United States
Motorcycle: 1983 GL1100I

Rev increase issue when Idle

Post by Trulylegend »



Hi! My I recently did a carburator rebuild on my Goldwing GL1100. Carbs worked well after testing for a week or two, although the testing was without the air filter housing/box installed. After installing the Airbox and filter, the bike started having an extremely odd idle.

First fire up for the bike had it dying and unable to keep idle rpm high enough. Second starts and subsequent starts had the bike switching between 1100-3000 rpm, with it fluctuating between the two. It would run fine for 30 seconds or so, idling near 1k, then run up to 3000 for a minute or two, then repeat.

I'm a Goldwing newbie, and a newer bike rider as well, so any help would be greatly appreciated!


MattMcCoy
Posts: 56
Joined: Tue Aug 25, 2020 5:31 pm
Location: Fort Worth, TX, United States
Motorcycle: 1983 GL1100A Aspencade

Re: Rev increase issue when Idle

Post by MattMcCoy »

You might have an air leak. Check gaskets on air box, O-rings where intake runners bolt into the heads, and hose clamps on the rubber boots of the runners. They should all be tight, but be careful so you don’t strip anything.
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winguyjo
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Re: Rev increase issue when Idle

Post by winguyjo »

i will be watching this with interest ...

i took my carbs apart for cleaning in the winter to fix an extremely minor flat spot around 3500 rpm. hardly noticeable but i am a glutton for punishment so i went ahead. i found the sliders on a couple of carbs just sticky enough to account for this, cleaned them up and re-assembled.

when i put them back on i had exactly the symptoms you are describing ... to a tee.

i took them back out thinking i had screwed up on float height or had missed some dirt. nope, floats bang on, clean as a whistle. re-installed and checked for vacuum leaks until i wanted to puke ... nothing. then it struck me ... when i was re-installing the jets (the ones that are held in with a retainer) i recalled thinking that the the o-rings weren't providing a tight seal but i didn't replace them. with nowhere else to look i decided to order carb kits ... DIDNT order randakks because i had been reading about long waits and customer service issues. when i installed the new o-rings i noticed a definite improvement but still just enough slop to make me wonder.

re-install the carbs and start her up ... HUGE improvement BUT the idle will still mosey on up to around 2000 (not 3000 anymore, and less frequently and stays there for a shorter duration). today i am taking it for it's first actual ride since all this started and hoping that it will clear it's throat, but those little o rings are a concern until and unless that happens.

good luck.
Trulylegend
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Joined: Tue Mar 30, 2021 3:22 pm
Location: Mesa, Arizona, United States
Motorcycle: 1983 GL1100I

Re: Rev increase issue when Idle

Post by Trulylegend »

I took a video for anyone interested. This is my issue when restarting the bike this morning.



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Maz
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Re: Rev increase issue when Idle

Post by Maz »

In the video, when it first starts, it's not firing on 4 cylinders, hence the knocking sound and low idle. When all 4 cylinders cut in, the revs rise and it smooths out (as you would expect). My guess is the carbs need revisiting. It's possible a couple of the idle circuits are blocked and the affected cylinders will only fire when the revs rise past the point where the idle circuits would normally operate.

Maz
Ironically, Common Sense is the LEAST common of all senses!
MattMcCoy
Posts: 56
Joined: Tue Aug 25, 2020 5:31 pm
Location: Fort Worth, TX, United States
Motorcycle: 1983 GL1100A Aspencade

Re: Rev increase issue when Idle

Post by MattMcCoy »

I agree — sounds like clogged idle circuits or jets. Which rebuild kit did you use? How do the tank, fuel lines, filter and pump look? Did you adjust the idle screw or idle mixture screw?
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dingdong
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Re: Rev increase issue when Idle

Post by dingdong »

Famous last words: "I rebuilt the carbs". Please give details of your rebuild such as did you use a kit? If so what kit? Did you replace any jets if you used a kit? After rebuild did you do an idle mixture screw adjustment? Did you balance the carbs? And just so you are clear any adjustments after rebuild need to be done "with" the air box and filter "installed".
Trulylegend
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Joined: Tue Mar 30, 2021 3:22 pm
Location: Mesa, Arizona, United States
Motorcycle: 1983 GL1100I

Re: Rev increase issue when Idle

Post by Trulylegend »

Hey, sorry on the late reply.

I should clarify that it was my friend (who is much more mechanically inclined than I am) who rebuilt the carbs. I'll ask him for a link to what he used and try to get an answer to the questions that have been posted here. Thanks!


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