Power loss and idle hunting issues


Information and questions on GL1500 Goldwings (1988-2000)
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Mattsoutloud
Posts: 3
Joined: Sat May 16, 2020 10:39 am
Location: Dallas, TX
Motorcycle: 1991 Goldwing 50th Anniversary Edition GL1500

Power loss and idle hunting issues

Post by Mattsoutloud »



Hey Guys,
Sorry in advance this is really a long post! But I'm stumped!
I have a 1991 Goldwing Aspencade 1500, with 33k original miles. It sat up for several months before I got it. It was my father's and I know he took great care until maybe the last year before he passed.
I've read everything I can find and watched tons of how to videos (Book marked several here to go back to later!) and nothing seems to be the answer to make it run right. I am at a loss for what else to try.

Initially, it wouldn't stay running and the floats were stuck. I had fuel dump on the floor.
I ran through a tank and a half of new fuel with Seafoam. This got it to run well enough to idle on it's own.

It will not start with the choke on now, but I had to use the choke before the Seafaom.
Now, it starts easily without choke but will not stay running. I feather in some starting fluid and keep it running until it warms up enough to keep running.
Maybe 2 or 3 minutes and then it generally idles ok, but it needs to be 1000 RPMs or more to be happy.
I can also just keep starting it until it will eventually idle on its own after working the throttle for a bit.
I took it out for about 20 minutes and eventually it started revving up and down, nearly dying.
Over 3K RPMS it sounds and runs great. Bogs when under that.

So, here's what I've done.

New air filter
New Fuel filter
New spark plugs
Checked all the linkages and they are all in good shape and move freely.
Checked for broken or leaking air lines. Not ruling it out, but everything looks good. Vaccum seems to hold well. I don't have a tester, just using finger.
Lots of things pointed to the Petcock, so I took Petcock apart to check. Looks good. No tears. "Seems" to hold pressure, but I plan to get a hose connected to it to check that it doesn't leak fuel and holds pressure while in place and fuel lines hooked up.
Removing fuel cap while running makes no difference. Some models have an air line? Mine does not.
Using throttle I can see fuel shoots in fine on both sides.
Everything I can see looks to be working as expected.

I'm an ok mechanic, but not brave enough to pull the carb all the way out to give it a proper once over.
I know 2 or 3 years ago it went into the shop due to a stuck float. Fuel dumping on floor.
Please let me know if there is something else I can try or have over looked.

This bike means a lot since my Dad left it to me after he passed last year. I'd like to see it back in working order. I hope to take my Mom for a ride over Christmas, it would mean the world to her and me.

Thanks!



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bellboy40
Posts: 781
Joined: Fri Nov 27, 2009 1:13 pm
Location: Brewton, AL
Motorcycle: 2000 GL1500SE Candy Spectra Red

Re: Power loss and idle hunting issues

Post by bellboy40 »

Well Matt, from your description, it sure sounds like those carbs are going to have to come out for a good cleaning. I had to do that about 3 years ago on a 94 model that was leaking around the fuel bowl gaskets. It is not fun but it is rewarding when you get through and she starts up and runs well.
Here is a link to Jim Martino's pages where he gives a great description of how to pull and clean the carbs with lots of good pictures. It was a big help to me when I did the carbs on mine. Good luck.
http://www.jmartino.me/carb/index.htm

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newday777
Posts: 1957
Joined: Tue Jan 11, 2011 5:21 pm
Location: Milford NH summer/fall & Oceanside, CA winters(N San Diego) with lots of miles riden between
Motorcycle: 2008 Cabernet Red. Level 4

1983 GL1100A Wineberry 36,000 miles

1975 CB750 K5 Planet Blue 7,800 miles

1976 CB750 K6 Anterris Red 25,000 miles

Past rides
1999A Restored from PO neglect & sold at 19,000 miles

1999SE Totaled by cager at 105,000 miles

Re: Power loss and idle hunting issues

Post by newday777 »

Welcome aboard Mattsoutloud

You said you pulled the petcock apart and found no cracks....
Did you hold the rubbers up to a light to inspect for cracks while pulling and bending the rubber?
You can bypass the petcock to test it by removing the hose from the fuel filter, remove the lower hose from the petcock that goes to the carbs and put the carb hose onto the filter output side to see if that helps. A leaking petcock will give you your hunting idle.

Did you do the flow test of the fuel pump to be sure it is operating correctly?

Flow test link
https://www.goldwingowners.com/threads/ ... 82&slide=0

You also might want to remove the fuel pump and inspect the tank for rust and debris. Fuel level must be below 1/2 tank before removal. If rust is present, I have cleaned several tanks in place using the electrolysis method.

Did you test for vacuum leaks with carb cleaner or an unlit propane torch(very low flow)? Or just a look see?


Other than that, I also agree that the carbs probably will have to come out and do a proper cleaning(full stip down including the air adjust screws, springs, washers and tiny o-rings, ultrasonic, boil cleaning or deep soak carb cleaner gallon can, not just spray can) and inspect the rubber diaphragms for cracks, replace rubber as necessary. Hopefully the last cleaning was done with Honda parts and not aftermarket carb kits. Honda brass parts are the best and can be cleaned rather than replaced. Jim's tutorial is the best to follow. Then adjust air screws with the idle drop method and follow up with a carb synchronization.

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DenverWinger
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Re: Power loss and idle hunting issues

Post by DenverWinger »

Under the rubber heat mat below the carbs is a vacuum hose with a pre-formed 90 degree bend. It is famous for developing a leak right at the bend and causing a "hunting" idle....

If you remove the carbs be sure not to skip checking this hose.
♫ 99 Little Bugs in the Code, ♪
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Andy Cote
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Location: Windham, ME
Motorcycle: 2015 Goldwing, basic black

Re: Power loss and idle hunting issues

Post by Andy Cote »

Condolences on the death of your dad. I think it's great you're keeping it and offering to take Mom for a ride.

Sounds like you have some good ideas already. You can turn up the idle adjustment until you get things sorted out.
2015 Goldwing, basic black

Previously: GL1200 standard, GL1200 Interstate, GL1500 Goldwing, GL1500 Valkyrie Standard, 2000 Valkyrie Interstate, many other Hondas

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ct1500
Posts: 1430
Joined: Wed Nov 10, 2010 8:09 pm
Location: Glastonbury,CT
Motorcycle: 1988 GL1500
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Re: Power loss and idle hunting issues

Post by ct1500 »

The engine did some setting so almost guaranteed you have plugged pilot jets to a degree. Do not cheap out and try to clean them or else you will very likely end up with a botched job having to do again like many before you in this situation. Replace the notorious vacuum line under the carbs and make sure the slides are working properly before beginning job. That is to see if they move freely opening and closing with engine off and that they move in tandem while running when cracking the throttle open hard and fast. Do a bench sync prior to install! If they are very close when checking then leave alone.
Two #20 pilot jets and two float bowl gaskets is the bare minimum for the job.
https://partsfinder.onlinemicrofiche.co ... COMPONENTS
https://www.jetsrus.com/individual_part ... 85_su.html
The issue regarding starting with choke you brought up has no correlation with the seafoam. The port for choke which provides AIR&FUEL on cold starts is below the throttle plates. To make the engine run somewhat you at some point cranked open the idle screw and in so doing reduced the vacuum available under the throttle plates which now is not sufficient enough to draw that mixture through the enrichment circuit.
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

User avatar
newday777
Posts: 1957
Joined: Tue Jan 11, 2011 5:21 pm
Location: Milford NH summer/fall & Oceanside, CA winters(N San Diego) with lots of miles riden between
Motorcycle: 2008 Cabernet Red. Level 4

1983 GL1100A Wineberry 36,000 miles

1975 CB750 K5 Planet Blue 7,800 miles

1976 CB750 K6 Anterris Red 25,000 miles

Past rides
1999A Restored from PO neglect & sold at 19,000 miles

1999SE Totaled by cager at 105,000 miles

Re: Power loss and idle hunting issues

Post by newday777 »

ct1500 wrote:
Sun Nov 22, 2020 10:02 am
Do not cheap out and try to clean them or else you will very likely end up with a botched job having to do again like many before you in this situation.
Bull.

The jets from Honda are cleanable(not spray cleaning!).
Aftermarket jets are notoriously inaccurate in machining.

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ct1500
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Re: Power loss and idle hunting issues

Post by ct1500 »

newday777 wrote:
Sun Nov 22, 2020 10:48 am
The jets from Honda are cleanable(not spray cleaning!).
I never wrote they were not. The OP mentioned he has a limited skill set regarding mechanics like many who visit this Forum and for a couple dollars on the low speed jets he just guaranteed himself factory new results. Many try the cleaning route and invariably come back with poor results. How many times would you like to see him do the job?
newday777 wrote:
Sun Nov 22, 2020 10:48 am
Aftermarket jets are notoriously inaccurate in machining.
I linked to OEM parts, did I not?
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

Mattsoutloud
Posts: 3
Joined: Sat May 16, 2020 10:39 am
Location: Dallas, TX
Motorcycle: 1991 Goldwing 50th Anniversary Edition GL1500

Re: Power loss and idle hunting issues

Post by Mattsoutloud »

That's for all the replies. So for sure I need to properly test the petcock and do a thorough vacuum line test.
The petcock actually looks new when i compared it to new replacements I've seen and old ones coming off.

I'm going to try the suggestions before giving in and pulling the carbs.
As old as it is, there's a good chance I'll replace a lot of the hoses as I go, no sense in doing this again in a couple of years over a cracked line.

If I do pull the carbs, I'll post back some pictures or videos of the triumph or tragedy!

Thanks again for the ideas I'll keep checking back for more ideas!

Solo So Long
Posts: 200
Joined: Thu Mar 26, 2020 4:07 pm
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Motorcycle: 1989 GL1500
1983 GW Interstate (ready to repair)
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Kawasaki Coyote (early 1970s)
Honda 350 (mid 1970s)
Kawasaki KZ900-PS (1977)
Honda Super Cubs (various years)
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Re: Power loss and idle hunting issues

Post by Solo So Long »

Mattsoutloud wrote:
Sun Nov 22, 2020 2:13 am
Initially, it wouldn't stay running and the floats were stuck. I had fuel dump on the floor.
I ran through a tank and a half of new fuel with Seafoam. This got it to run well enough to idle on it's own.
Seafoam is wonderful stuff, but one treatment might not be enough for the amount of gummy fuel you had.

Also, just because you're not dumping fuel doesn't mean that BOTH carbs are behaving now. You could have had one jammed open and the other jammed closed, and now have one ALMOST jammed open and the other still stuck.

I'm suspecting that it was on the side stand, and the left carb was stuck open. If so, that one got most of the new gas and Seafoam, simply because it had so much flowing through it.

Since you obviously intend to keep this bike, I strongly advise that you get a carb synchronizer, spark checker, infrared thermometer and mechanic's stethoscope (these tools let you work magic diagnosing a boxer engine). Check the airflow with the synchronizer -- they should be fairly close. If they are way different, but the sliders are open to pretty much the same distance, you have an air leak or a constriction.

If the synch looks good, then IRAN the carbs and gaskets (factory rebuild kit, if needed, but may just need to soak in Seafoam overnight).



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