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I have been searching high and low and can't find a good video or a good step by step on how to sync the carbs on my 1500. I had the carbs rebuilt by a rep vendor and feel they did a great job but they could only set it up on a bench. I feel certain they are out of sync. the issue I am having is once it's warmed up it has a healthy hesitation on the low end until you get close to 3K when under a load as in taking off it wants to stall unless you crank the throttle, but once it's moving it does good, the hesitation is still there but not enough to stall the bike. it pops a little on decel but not bad
it will idle good and has strong accel when just sitting there. also it seems to run worse when to motor is cooler. this past weekend we were in the mountains and when we would drop down in the valley it would start hesitating more. I added some pre filter foam over the intake horn and it will run a little better but still hesitates at low end. I am getting a sync kit but need a good guide to go by to get it right. any help will be greatly appreciated
 

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so if not sync issues what would you think, still have a vacuum leak ?, I replaced a couple hoses while carbs were off to include the 90 deg. one that fails so often

Better detail of my explanation of what it is doing as I don't think I said it correctly. It isn't actually hesitating but rather unable to hold a steady low RPM from sitting still ONLY once the bike is moving I can let the RPM drop and it will throttle up just fine, and that is when it will hesitate a little until the RPM's get to about 2.5 to 3K . what happens is I crank it cold using the enricher and it warms up just like it should, running nice and smooth, then once warm, which does take longer than my 97 it will idle good, tiny surging but runs good. so then if a try to raise the RPM slowly to lets say 2K and hold it there it will go up there smooth but after about 2 to 3 secs it will just begin to stall out and if I ease off the throttle it will recover for a second then begin to stall again. if I don't accel or just let off at this point it will die. so cracking the throttle gently off idle is where it all goes bad.
 

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Discussion Starter #4
Thank you for that link, that is what I have been trying to find
 

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Hesitation to me, says the Acceleration Pump is not working right.
take the air filter off, and twist the throttle hard, do both carbs get the same amount of fuel squirted down into the throats?

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Discussion Starter #6
Hesitation to me, says the Acceleration Pump is not working right.
take the air filter off, and twist the throttle hard, do both carbs get the same amount of fuel squirted down into the throats?

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I will be double checking that carefully when I get back into it this weekend but yes it was working good before when I was working on it and pulled the carbs and had them rebuilt
 

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Sounds like it's too lean in the mid range, like maybe floats too low.
 
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so if not sync issues what would you think, still have a vacuum leak ?, I replaced a couple hoses while carbs were off to include the 90 deg. one that fails so often

Better detail of my explanation of what it is doing as I don't think I said it correctly. It isn't actually hesitating but rather unable to hold a steady low RPM from sitting still ONLY once the bike is moving I can let the RPM drop and it will throttle up just fine, and that is when it will hesitate a little until the RPM's get to about 2.5 to 3K . what happens is I crank it cold using the enricher and it warms up just like it should, running nice and smooth, then once warm, which does take longer than my 97 it will idle good, tiny surging but runs good. so then if a try to raise the RPM slowly to lets say 2K and hold it there it will go up there smooth but after about 2 to 3 secs it will just begin to stall out and if I ease off the throttle it will recover for a second then begin to stall again. if I don't accel or just let off at this point it will die. so cracking the throttle gently off idle is where it all goes bad.
I agree with DaveO. It sounds like you have an issue with the low speed circuit. The low speed circuit is important at lower RPM as it's name implies. As you get to higher RPM the main circuit will sustain performance and the low speed circuit really does nothing.
Have you tried turning the low speed (isle)mixture adjusting screws out a bunch to see what happens? That could give you a clue. If the adjustment does nothing you might have a plugged low speed circuit. This is extremely common or even expected when a bike is stored for extended periods.
 

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Discussion Starter #10
quick history, bought after sitting, replaced vacuum hoses as needed, new air filter full tune up and all fluids, removed carbs and sent off to have rebuilt, so I truly hope I'm not looking at an issue inside the carbs,
I have not messed with the idle mix screws in any way since carbs were rebuilt
 

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quick history, bought after sitting, replaced vacuum hoses as needed, new air filter full tune up and all fluids, removed carbs and sent off to have rebuilt, so I truly hope I'm not looking at an issue inside the carbs,
I have not messed with the idle mix screws in any way since carbs were rebuilt
The mixture screws is an adjustment that should be done after the carbs are installed on your bike. If you read your manual it will mentuion a 50 RPM lean drop for emissions. I would skip the lean drop as it will aggrevate the issue you are fighting. Do adjust the mixture screws though. If the low speed circuit is plugged the mixture screws will have no affect.
 

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Discussion Starter #12
so it looks like the concensus is it is more likely that the fuel air mix is off than sync issues so this is what I will work on first, hopefully that will solve everything
I will post back once I do it. going to try to get to it this weekend but wifey has some other plans as well
Thanks for all the help so far
 

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so it looks like the concensus is it is more likely that the fuel air mix is off than sync issues so this is what I will work on first, hopefully that will solve everything
Agreed, the sync adjustment is mainly to balance out your idle. Once you are off idle with the throttle open some, the sync adjustment becomes insignificant and the more the throttle is opened, the less carb sync matters.
 
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As Denver said. With a GL1500 you have 6 cylinders. Could say you have a 6 horse hitch. You want all 6 to work together. Not 3 working and 3 loafing..That is all a sync does.
 

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Discussion Starter #15 (Edited)
just an update, I tried to adjust the air fuel mix and anything above 2 turns out just made matters worse. when trying to adjust the idle with the thumb screw once It got about about 600 RPM it would just stall the engine rather than raise the idle. the only way I could make it run was to create a large restriction at the carbs, more than just putting the filter back in would create. but I could make it run smooth and accel like it should but that is not a fix. it's like it is getting too much air all the time. I did make myself a nice set of adjusting tools that I think came out nice, it allowed me to minimize that plastic I had to remove to get to the screws I'll be checking the acceleration pump next, it works like it should with engine off but not sure about when it's running. I didn't get a chance to look at that this weekend. hopefully get to check it tonight
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Accelerator pump will not be the issue.. It does not even really come in to play until you accelerate pretty quickly. I think you are sort of right and wrong. It does not need less air it needs more gas. I would touch base with the guy who did the carbs. I think it is his issue. Either a float level issue or a plugged low speed circuit. It needs more fuel/
 

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Discussion Starter #18
Thanks Redwing

Dennis
it's not OEM Honda but is proper paper/wire mesh replacement,
I run a K&N on my 97 and have for years with no issues

going to piddle with it just a tad tonight, someone pointed out I had bypassed the fuel petcock valve (because it was leaking) but I didn't plug the vacuum hose that works it. I never even thought about the vacuum hose. going to plug it tonight to see if that makes a difference and set the air fuel mix back to factory setting of 2 turns out.
I'm going to feel like an idiot if all this time it was because my fuel petcock valve was leaking and then when I bypassed it I didn't block the vacuum hose. I have a kit ordered for the valve but it hasn't come in yet
 
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Thanks Redwing

Dennis
it's not OEM Honda but is proper paper/wire mesh replacement,
I run a K&N on my 97 and have for years with no issues

going to piddle with it just a tad tonight, someone pointed out I had bypassed the fuel petcock valve (because it was leaking) but I didn't plug the vacuum hose that works it. I never even thought about the vacuum hose. going to plug it tonight to see if that makes a difference and set the air fuel mix back to factory setting of 2 turns out.
I'm going to feel like an idiot if all this time it was because my fuel petcock valve was leaking and then when I bypassed it I didn't block the vacuum hose. I have a kit ordered for the valve but it hasn't come in yet
Possible but that is a pretty small line. Step in the right direction for sure.
When Honda says 2 turns on mixture screws that is just a suggested starting point to get you running. You tune them after running and up to temperature for the smoothest 750 or less idle. I don't do the 50 RPM lean drop. I know, I'm bad. I pollute.
 

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Discussion Starter #20
the main reason I say I'm going to put it back is when I opened them a little more it wouldn't even idle anymore without me restricting the airflow on top of the bowls
I thought I was dealing with a lean condition not I'm not so sure it was even off at all
I have to figure out why when I try to raise the throttle with the thumb screw to get it to idle at 750 to 800 it will die instead of raise the idle. I never really picked up on it until now with the air filter out
before it would raise the idle but it also made the throttle down very slow, I mean slow as in let off throttle then wait, wait, wait now shift but if I kept it right at or just under 750 it was fine
I can crank my 97 up and all it does is idle high, I did that when I was first teaching my wife how to ride, that way she didn't struggle with taking off until she got the hang of it, then I turned it back down
 
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