Surging under acceleration/steady load


Information and questions on GL1500 Goldwings (1988-2000)
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crusty1500
Posts: 13
Joined: Sun Sep 15, 2024 5:23 pm
Location: Kingsport, TN
Motorcycle: 1989 GL1500 A
2005 VTX 1800F

Surging under acceleration/steady load

Post by crusty1500 »



Hello all!

First post on the forum, just wanted to introduce the bike and myself. First this is my first wing of any era, I've always wanted one and found this one at the right price. It's sat for roughly 20 years (last registration was 2004) and I bout it running but not quite road worthy. Changed the timing belts and coolant, new plugs, cruise and sub air filters replaced, cleaned the K&N it came with, new front and rear rubber and all three master cylinders rebuilt. When I first got it she ran rough. I pulled the carbs, rebuilt them and replaced several vacuum lines that were questionable (both 90s under the black mat, several other smaller lines, line to the petcock), rebuilt the petcock, and checked the vacuum lines on top and they seem fine. Issue I'm having is she idles perfectly smooth, but under a load it seems lean and has a surge. Under an acceleration it's much smoother, but steady load it's worse. I've read about the coolant temp sensor for the ECU and am debating it, but I wonder if there's something else I'm missing. Any thoughts are much appreciated!


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crusty1500
Posts: 13
Joined: Sun Sep 15, 2024 5:23 pm
Location: Kingsport, TN
Motorcycle: 1989 GL1500 A
2005 VTX 1800F

Re: Surging under acceleration/steady load

Post by crusty1500 »

Few additional things: checked spark on both banks and checked compression. Bike has 150 psi on all 6 and good spark. Checked inside the carbs while running and I can see fuel being drawn out, so I must be missing something. Plan on doing a seafoam treatment first for a few tanks before ripping the carbs back out.
bbrackett
Posts: 142
Joined: Mon Oct 01, 2018 6:15 am
Location: Sedalia, MO
Motorcycle: 1988 GL1500

Re: Surging under acceleration/steady load

Post by bbrackett »

I had an issue like that, it felt like someone was turning on and off the ignition, didn't feel like a fuel issue
What I found when I replaced my belts, was magnetic crap on the Ignition pickup coil/sensors.. I cleaned that stuff off.. and that issue went away !!
so.. if you didn't clean your Ignition pickup coil/sensors you may want to do that..

ps.. when I replaced my belts, I only removed the Right Side Engine Protection Bar
took the center inspection cover off
and I was able to slide both covers off WITHOUT removing the Coolant Hose !!

Could be fuel bowl level or dirty mains or a vacuum leak going to the sliders

on my Ignition Module, I also found the vacuum line plugged on the module side !!..

You may want to get a dual carb Vacuum Gauge kit and check stuff further, maybe while riding.. (carefully)
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crusty1500
Posts: 13
Joined: Sun Sep 15, 2024 5:23 pm
Location: Kingsport, TN
Motorcycle: 1989 GL1500 A
2005 VTX 1800F

Re: Surging under acceleration/steady load

Post by crusty1500 »

It doesn't feel like an ignition cut, more like you're rolling off and on the throttle smoothly. When I changed the vacuum lines it has started to run better, and the more I run it the better it gets. I have set the fuel sync while hot and I'm running some seafoam through the fuel as well. The pickup coils were clean when I changed the belts, no junk on them at all. The more I research the more it seems like that coolant temp sensor is more an issue on the 90+ models but I could be mistaken. As far as taking the sync tool on a ride, I might just do that tomorrow and see what it's doing under load. Also, with the air filter off you can blip the throttle and both slides move so I don't think that's an issue. They also don't stick at any point in the bore.
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crusty1500
Posts: 13
Joined: Sun Sep 15, 2024 5:23 pm
Location: Kingsport, TN
Motorcycle: 1989 GL1500 A
2005 VTX 1800F

Re: Surging under acceleration/steady load

Post by crusty1500 »

Also, float levels might need to be checked. I did briefly when the carbs were off but it wasn't measured of anything.
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crusty1500
Posts: 13
Joined: Sun Sep 15, 2024 5:23 pm
Location: Kingsport, TN
Motorcycle: 1989 GL1500 A
2005 VTX 1800F

Re: Surging under acceleration/steady load

Post by crusty1500 »

Btw here's a pic of the old girl.
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crusty1500
Posts: 13
Joined: Sun Sep 15, 2024 5:23 pm
Location: Kingsport, TN
Motorcycle: 1989 GL1500 A
2005 VTX 1800F

Re: Surging under acceleration/steady load

Post by crusty1500 »

Done some more testing and I'm fairly certain it's either a vacuum leak or one carb is very lean. Going to do some more checking but I want to post follow ups/resolution so anybody that may come across this thread doesn't find an dead end.
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crusty1500
Posts: 13
Joined: Sun Sep 15, 2024 5:23 pm
Location: Kingsport, TN
Motorcycle: 1989 GL1500 A
2005 VTX 1800F

Re: Surging under acceleration/steady load

Post by crusty1500 »

Alright, more information so any help is appreciated. Decided to check the plugs and they're black and sooty, obviously it's not lean at all. Also, when I pulled the carbs again there was fuel in the vacuum lines attached to the carbs. Check the vacuum line to the petcock and there's no fuel in it, so I suspect the petcock is fine but maybe the float levels are too high or the diaphragm for the carb slide(s) is allowing gas to be sucked into the vacuum lines. Carbs overall look really good and clean, so it has to be something simple. I sprayed all the vacuum lines with it running and there was no change in idle RPMs no the smell of burning carb cleaner. Read that float height should be 7.5 mm, so this will be fun to do. Any other thoughts are welcome, thanks all for the help so far.
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Rambozo
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Location: Disneyland
Motorcycle: 1992 GL1500 Aspencade
Ducati Monster

Re: Surging under acceleration/steady load

Post by Rambozo »

Be sure the needle spring is not compressed when measuring the float level. Don't turn the carb upside down.
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crusty1500
Posts: 13
Joined: Sun Sep 15, 2024 5:23 pm
Location: Kingsport, TN
Motorcycle: 1989 GL1500 A
2005 VTX 1800F

Re: Surging under acceleration/steady load

Post by crusty1500 »

Good to know. I'm going to pull the carbs back apart fully and double check everything.
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Sassy
Posts: 710
Joined: Thu Nov 05, 2020 12:15 am
Location: Wynndel BC Canada
Motorcycle: 1989 gl1500

Re: Surging under acceleration/steady load

Post by Sassy »

I'm not versed at all in the carbs as mine work good.
I just wanted to say thank-you for realizing a dead end thread is the worst and following up on your progress.
Enjoying the Darkside
Fred
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crusty1500
Posts: 13
Joined: Sun Sep 15, 2024 5:23 pm
Location: Kingsport, TN
Motorcycle: 1989 GL1500 A
2005 VTX 1800F

Re: Surging under acceleration/steady load

Post by crusty1500 »

I agree, nothing worse than going through a thread that has similarities to what you're facing with no resolution.

On the other side, I pulled the carbs apart fully, cleaned all the jets, circuits, enrichment circuit everything. It seems like the slides are much smoother and the actual throttle action is cleaner. I didn't get the carbs back on yet though, going to try and do that today. I replaced the needle and seat and set the float heights like rambo suggested. Just a word of caution for anybody that might be as hopefully as I was: just because the bike runs doesn't mean the carbs need a light cleaning. You won't get away with it, pull it apart fully the first time and clean it.
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crusty1500
Posts: 13
Joined: Sun Sep 15, 2024 5:23 pm
Location: Kingsport, TN
Motorcycle: 1989 GL1500 A
2005 VTX 1800F

Re: Surging under acceleration/steady load

Post by crusty1500 »

Just another quick update. Haven't been able to ride to test this week, but I double checked the 90* elbows under the carbs and one was pretty loose. Hose clamped all four connections and the bike seems to idle and fireup much better. I forgot to hook the cruise back up after I got the airbox on so that gets to come back off, lucky me. Otherwise I'll just have to ride and double check carb sync. It seems fairly close just on a basic checkup but it'll have to be verified. Hopefully tomorrow will yield a solution to this thread!
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crusty1500
Posts: 13
Joined: Sun Sep 15, 2024 5:23 pm
Location: Kingsport, TN
Motorcycle: 1989 GL1500 A
2005 VTX 1800F

Re: Surging under acceleration/steady load

Post by crusty1500 »

I'm really at a loss now. Carbs should 100% be clean as I took it apart and cleaned them again. Just finished hooking it up to a smoke machine and there is no smoke coming out of any vacuum lines. I'm completely baffled now. The only thing I can think of is the k&n is so wore out its not sealing good and it's allowing too much air and leaning the carbs. The only other thing I can think of is the accelerator pump. It's an 89 which is one of the problem children from my research, but it discharges a decent stream when the throttle is twisted.

*Edit: I verified the timing belts are timed correctly to rule that out. Plugs are decently dark but it has mostly idled instead of being under a load condition, but the only thing I can draw is the accelerator pump discharge is weak off idle and/or the air filter isn't enough of a restriction. Vacuum gauge shows no issues, holds steady vacuum but there is a slight dip in the idle when warm (maybe 50 or 100 rpm, not much). I'll take any and all suggestions though!


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