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Working on the new 89. It had been sitting over a year. Fixed the melted wires and got it fired up.

It had a real bad surging at idle. I guess the po had the idle set to around 2000 rpm so it would stay running. But I'm guessing on that part. It had a real bad off idle stumble. I rode it. Once you get past that stumble it runs strong. But it was hard to ride because of the high idle and bad surging.

The gas tank was near empty. I put about a gallon or so of gas and a heavy dose of red bottle heet with injector cleaner in it. I rode it until that was about gone.

I then put a heavy dose of sea foam and $5 worth of gas. After going about 2 miles I could feel it was different. The more I rode it the better it got. I was able to get it to idle at about 900. The surging was still there but not as bad.

I rode it again yesterday with another heavy dose of sea foam and more gas. I put 100 miles on it and topped it off with straight gas, By the end of the day I had a near normal idle with only a little surging. This bike runs very strong. There is a very slight stumble off idle, sometimes.

Today I changed spark plugs, fuel filter, and air filter. It's a little better, bike runs strong, but still have that slight surging at idle. Seems smooth with cruise on.

The plugs on one side look like they've barely been used. The other side look just a little black/wet on one spot on each plug. Smells like it might be running rich.

I could be wrong, but I think it runs too good to be a carb problem. Or could it be? No choke needed once it warms up. I am getting a little cackling/backfiring when I let of the gas if running hard. The exhaust is very quiet. No leaks, at least I don't think there is.

I've read that it can be many things like vacuum lines, a couple of elbows under the carbs. Trying not to pull the carbs unless I have to. The bike runs so good. I've also read about the temp sensor could be it.

I read info on the part number for the sensor but it's for newer models. Mine comes up a slightly different number. Mine calls for 36151-MC7-003 where as later model call for 36151-MT8-003. The 3 middle numbers are different. Looking at the pics of the 2 sensors on Partzilla they look the same except the plug connector.

I guess what I'm getting at is this the similar sensor that could be causing my problem? Do you have to remove the carbs to change it?

Also. My friend said he thinks he remembers the 88-89's having this surging and they never could fix it. Any truth to that?


Look at part 19 on the 89 .
https://www.partzilla.com/catalog/honda/motorcycle/1989/gl1500-a-gold-wing/water-pipe

Look at part 22 on the newer models.
https://www.partzilla.com/catalog/honda/motorcycle/1993/gl1500a-a-gold-wing-aspencade/water-pipe

Is part 19 what I need?

Thanks for any input.
 

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Piaggio MP3, was 02 GL1800
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I remember a lot of talk about changing the spark timing on the 88 and 89
 

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Yes it is most likely a carb problem, either float bowl overfilling or a plugged idle air jet.
 

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'85 gl1200
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57 Posts
Working on the new 89. It had been sitting over a year. Fixed the melted wires and got it fired up.

It had a real bad surging at idle. I guess the po had the idle set to around 2000 rpm so it would stay running. But I'm guessing on that part. It had a real bad off idle stumble. I rode it. Once you get past that stumble it runs strong. But it was hard to ride because of the high idle and bad surging.

The gas tank was near empty. I put about a gallon or so of gas and a heavy dose of red bottle heet with injector cleaner in it. I rode it until that was about gone.

I then put a heavy dose of sea foam and $5 worth of gas. After going about 2 miles I could feel it was different. The more I rode it the better it got. I was able to get it to idle at about 900. The surging was still there but not as bad.

I rode it again yesterday with another heavy dose of sea foam and more gas. I put 100 miles on it and topped it off with straight gas, By the end of the day I had a near normal idle with only a little surging. This bike runs very strong. There is a very slight stumble off idle, sometimes.

Today I changed spark plugs, fuel filter, and air filter. It's a little better, bike runs strong, but still have that slight surging at idle. Seems smooth with cruise on.

The plugs on one side look like they've barely been used. The other side look just a little black/wet on one spot on each plug. Smells like it might be running rich.

I could be wrong, but I think it runs too good to be a carb problem. Or could it be? No choke needed once it warms up. I am getting a little cackling/backfiring when I let of the gas if running hard. The exhaust is very quiet. No leaks, at least I don't think there is.

I've read that it can be many things like vacuum lines, a couple of elbows under the carbs. Trying not to pull the carbs unless I have to. The bike runs so good. I've also read about the temp sensor could be it.

I read info on the part number for the sensor but it's for newer models. Mine comes up a slightly different number. Mine calls for 36151-MC7-003 where as later model call for 36151-MT8-003. The 3 middle numbers are different. Looking at the pics of the 2 sensors on Partzilla they look the same except the plug connector.

I guess what I'm getting at is this the similar sensor that could be causing my problem? Do you have to remove the carbs to change it?

Also. My friend said he thinks he remembers the 88-89's having this surging and they never could fix it. Any truth to that?


Look at part 19 on the 89 .
https://www.partzilla.com/catalog/honda/motorcycle/1989/gl1500-a-gold-wing/water-pipe

Look at part 22 on the newer models.
https://www.partzilla.com/catalog/honda/motorcycle/1993/gl1500a-a-gold-wing-aspencade/water-pipe

Is part 19 what I need?

Thanks for any input.
Your carbs are out of synch. Which ever side has the wet plugs, is the side on which the carb is out of synch.
If you've never done a carb synch, on the 1500, it is a bear. The carbs are buried deep down, the air/fuel adjuster is only accessable from the front and the adjuster head is shaped like a D. The tool to adjust it is only available from Honda and costs about $70.
Being the cheap guy that I am, I fashioned a tool from a piece of hard copper tubing that finally worked. Unless you have the patience of Job, I don't recommend that. You MIGHT find a shop that will rent that tool to you. You may pay the retail price, then get most of it back when you return it.
What you'll need is a pair of vacuum gauges with metering valve (some use the rolling wheel like an IV in the hospital.) and about 4 feet of vacuum hose. These gauge sets can be bought from Ebay.
On your intake manifold, close to the heads is a screw that seems to do nothing more that plug a hole. That's because it does nothing more than plug a hole. You'll need a short piece of threaded tubing that will screw into that hole and leave at least a couple of inches showing. These little vacuum pipes can be bought off Ebay. Connect one of the gauges to each vacuum pipe, close the metering valve on the gauges. Crank the engine and let it warm up.
Slowly open the metering valve until the needle moves on the gauge. Same on the other gauge. If the needle is shaking, close the metering valve until it quiets down.
POINT; The carbs are on opposite sides than the head it feeds. If you are looking the left side head, as you sit on the bike, the carb will be on the right side of the engine.
Now comes the fun part. Just above the radiator, looking at the front of the bike, there are two hard-to-find passage that leads to the aforementioned "D shaped hard to find and just as hard to reach, air/fuel mixture adjusters".
It is such small opening that you can not hold a light up to it and stick the unGodly expensive and probably never again needed adjustment tool into it at the same time. It is a "look with a light, then, try to find the D. Repeat until you feel the tool mate up with the D. Are we having fun yet? Aren't you glad you don't have to do this at every oil change?
The point is to bring the vacuum reading on both carbs as high as you can, as long as both sides read the same vacuum. If one won't go as high as the other, then lower the high one to match the lower one.
The idea is to reach the highest matching vacuum reading on both carbs. I would check to see if the carb that feeds the side with the wet plugs isn't the culprit. If it is way different than the dry plug side, adjust it first, remembering that the carb is on the opposite side from that head. Looking from the saddle, right carb feeds left head and visa versa.
I just know that you are celebrating that you don't have to do this with four or even worse, six, on the GL1500 Valkyrie.
Have fun. Ride much, Ride Safe.
Be blessed.
 

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Your carbs are out of synch. Which ever side has the wet plugs, is the side on which the carb is out of synch.
The idea is to reach the highest matching vacuum reading on both carbs. I would check to see if the carb that feeds the side with the wet plugs isn't the culprit. If it is way different than the dry plug side, adjust it first, remembering that the carb is on the opposite side from that head. Looking from the saddle, right carb feeds left head and visa versa.
You are confusing 2 operations. You describe the fuel mixture adjustment which is different from the synch adjustment and other such misinformation, the right carb feeds the right, left carb feeds the left, they don't cross over.
 
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2012 GL 1800
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My 88 had a slight off-idle hesitation when it was brand new. I asked the dealer about it, and he said, "Yeah, they do that."

I just got used to it and put about 100K miles on it. Shortly before I sold it, I seem to recall reading a service bulletin about it. It didn't amount to a recall, but Honda had some sort of suggestion. I apologize that I don't remember the details. It might be worth searching for someplace that archives old service bulletins.

Good luck, or just accept it like I did. :)
 
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