99 gl1500 random misfires


Information and questions on GL1500 Goldwings (1988-2000)
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Bikerdave79
Posts: 32
Joined: Sat May 21, 2016 9:55 am
Location: Dallas, PA
Motorcycle: 1983 gl1100a Aspencade

99 gl1500 random misfires

Post by Bikerdave79 »



Ok so I've been pulling my hair out with this bike. It was sitting in a heated garage for 7 years. Dumped the bad gas, replaced a busted auto petcock diaphram rebuilt the carbs, changed all fluids. It runs beautifully except at idle I get a slight stumble. And anywhere in the upper rpm range in neutral it stumbles from time to time like a random misfire. While riding the bike it pulls great and has tons of power. But if you leave off the throttle for a few seconds then jump back into it, it will die out for half a second before catching itself. Also every time pulling away from a stop, (clutching out in first) the engine stumbles and dies. Unless you hold the RPMs up a bit. I can't for the life of me figure this out. I don't think it's a fuel issue due to it stumbling at all rpm ranges. It also had a surge when I first started so I replaced the intake temp sensor which cured that but this stumbling remains. The carbs were rebuild, the carb manifold boots are brand new and I went over all the hoses for vacuum leaks. It really feels almost like the bike hiccups and takes a second to catch up. And when the throttle is held up in neutral it sounds like maybe about every 2 or 3 seconds one or more of the cylinders are missing a beat. Plugs were not changed but they look to be in almost new condition. Burn pattern looks good on all of them. I thought maybe a coil but would both of them just randomly cut out? I tested each wire with a spark tester while running the bike and the spark seems consistent. Although I can't really tell if it's advancing properly which makes me lean toward that being an issue. Is there something else like a ground issue or electronic part that I'm overlooking? Thanks in advance!



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ct1500
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Motorcycle: 1988 GL1500
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Re: 99 gl1500 random misfires

Post by ct1500 »

Pulls great and has tons of power but can't take off from a standstill. :) You do not know how well these things can run when all is okay. :)
It is 99% of the time carburation when these don't run right. Check for RPM changes with carb clean spray by following this here.
https://www.goldwingfacts.com/threads/1 ... t.4246066/
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

Bikerdave79
Posts: 32
Joined: Sat May 21, 2016 9:55 am
Location: Dallas, PA
Motorcycle: 1983 gl1100a Aspencade

Re: 99 gl1500 random misfires

Post by Bikerdave79 »

Yea it's not my first rodeo, been fixing bikes for years. Goldwings are just a pain in the butt compared to harleys. Yea I've gone over all the Intake there are zero vacuum leaks. Carbs were fresh rebuilt and ultrasonic washed. New gas, new lines.. Carb manifolds are brand new. Vacuum lines all changed out. Vacuum guage reads right on, synch is perfect and pilot mixtures are dead nuts (verified with manometor and colortune plugs) fuel mix has the combustion a nice bright blue. It just seems run beautiful and then randomly stumble at times. It DOES do it throughout the rpm range but can only notice it in neutral with the throttle turned up. I guess it's always doing it but you just can't feel it under load. It's a trike so the bike is heavy. It still gets out of it's own way. feels like it straightens out under load, Or not enough to be noticeble. Just off idle is when it wants to puke out because of the stumble causing a power loss for a second.

I have however noticed after putting a few miles on the bike the headlight seems very dim, cruise doesn't want to work all the time, left turn only works if you put the right on first. And the radio seems to have a lot of static. I'm thinking I may have a bad ground somewhere. I treated the bulk connectors under the right hand fairing with dialectic grease when I had them apart but never messed with any of the main battery cables. That Would explain a lot of it was a faulty ground and I'm seeing that ground issues are common on these. So I think I'm gonna tear back into it this weekend and I'll let you know what I find

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minimac
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Re: 99 gl1500 random misfires

Post by minimac »

Bikerdave79 wrote:
Fri Sep 11, 2020 11:47 am
Yea it's not my first rodeo, been fixing bikes for years. Goldwings are just a pain in the butt compared to harleys.
You now have three times the cylinders and everything is protected better(hidden)from the elements. They don't break often, so of course it'll seem difficult! Running issues (misfire,stumble, etc.) are carb/fuel/vacuum related or electrical.

Bikerdave79
Posts: 32
Joined: Sat May 21, 2016 9:55 am
Location: Dallas, PA
Motorcycle: 1983 gl1100a Aspencade

Re: 99 gl1500 random misfires

Post by Bikerdave79 »

minimac wrote:
Fri Sep 11, 2020 12:42 pm
Bikerdave79 wrote:
Fri Sep 11, 2020 11:47 am
Yea it's not my first rodeo, been fixing bikes for years. Goldwings are just a pain in the butt compared to harleys.
You now have three times the cylinders and everything is protected better(hidden)from the elements. They don't break often, so of course it'll seem difficult! Running issues (misfire,stumble, etc.) are carb/fuel/vacuum related or electrical.
Also doesn't help they cram 100 lbs of sh** into the space between your legs. I'm not scared to work on anything I understand the systems and how they work. Just a pita that you have to spend an hour stripping off all the plastic just to work on the dang thing. 🤣

FM-USA
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Re: 99 gl1500 random misfires

Post by FM-USA »

.
BikerDave79
You could remove the tupperware T'ween your legs and WRAP your Wing with this...
Black Bungee hooks to hold'r down.
SUPER EZ to remove.

. :P


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Bikerdave79
Posts: 32
Joined: Sat May 21, 2016 9:55 am
Location: Dallas, PA
Motorcycle: 1983 gl1100a Aspencade

Re: 99 gl1500 random misfires

Post by Bikerdave79 »

Well I discovered the problem and the fix! She runs perfect now. It turned out the accelerator pump diaphram was rather stiff from age. I didn't catch the first time I had inspected it. But the stiffness was keeping it from fully returning to a resting position. Which in turn led to lack of fuel spray when accelerating just off idle (where I was having the lag issue) put in a fresh diaphram and now the throttle is very snappy and no dead spots. the electrical stuff I was experiencing was due to a cruddy connection at the left handlebar control plug. Got it back together today and she runs smooth as glass. The biggest headaches are always something dumb 🤷‍♀️

FM-USA
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Re: 99 gl1500 random misfires

Post by FM-USA »

FIXED!




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