'92 carb base settings


Information and questions on GL1500 Goldwings (1988-2000)
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754
Posts: 96
Joined: Fri Sep 08, 2017 9:08 am
Location: Clermont Ga
Motorcycle: 1992 GL1500 Interstate

1978 CB750 Supersport

'92 carb base settings

Post by 754 » Sun Mar 17, 2019 6:32 pm



Good evening all,

I have a question for those who know these carbs well. I have finally had a chance to get back to working on the wing this week. I have it running, just not running well. It's still a head scratcher. I know they are absolutely clean, I personally cleaned them and confirmed their cleanliness not long ago, all passages and jets are clear. They work well with no binding of any sort. Pilot screws are at 2 turns out per the shop manual and it's just not quiet right. I know there are no vacuum leaks, I used my home made smoke machine and smoked both manifolds and I did not see a single leak.

I reset the pilot screws last year to restart the idle drop process, as it ran extremely rich at idle and the fuel economy was not what it should have been. Somewhere along the way I lost the piece of paper on which I had written what I assume was the original pilot screw settings.

There seems to be a lack of information regarding setting the carbs up aside of the pilot screws. Does anyone know how the throttle butterfly's should be set? Are they set to be completely closed or do they need to be open some at idle? If so, any idea as to how open they should be (business card thickness, 1/16", 1/8" ect...)? I know my cb750 carb slides are set to approximately 1/16" to start balancing and tuning. The weather is getting nice and I want to ride to work again, I need to get this project completed. The cb750 is still waiting for its top end rebuild.

It ran great before I reset the pilot screws and I know it will again.

Thanks all,

Travis


1992 Goldwing Gl1500 Interstate

1978 CB750 Supersport

User avatar
754
Posts: 96
Joined: Fri Sep 08, 2017 9:08 am
Location: Clermont Ga
Motorcycle: 1992 GL1500 Interstate

1978 CB750 Supersport

Re: '92 carb base settings Update!

Post by 754 » Tue Mar 26, 2019 10:54 am

Hey everyone,

As I said in my first post I have the bike running well right now. I noted an interesting find the other day, the main jet on the right hand carb is letting fuel by. It is actually a pretty noticeable thing causing fuel to puddle up on top of the throttle plate. I cleaned and visually check the needle and there appears to be no damage to it. Now I have not really considered taking the needle seat out but, I guess now I have to. 2 questions, the first is does the needle seat come out using a drift and hammer or does it screw out? Second question is it still available? The needle is not that I see, I'm hoping there is no damage and to be able to clean the seat and get it all to seal again. Any information is always appreciated.

Thanks,

Travis
1992 Goldwing Gl1500 Interstate

1978 CB750 Supersport

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ct1500
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Motorcycle: 1988 GL1500
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Re: '92 carb base settings

Post by ct1500 » Tue Mar 26, 2019 6:41 pm

A properly functioning carburetor does not allow fuel to drip out of the slide needle port at an idle. Venturi vacuum is needed to draw it out which is only available twisting the throttle hard and fast at idle or while underway with throttle opened a good bit. Slides are the carburetors secondary main fuel circuit and can be manually opened while idling with no fuel introduced to the incoming air due to low/virtually non-existent venturi vacuum.
Look more closely with a flashlight to see if the fuel is actually coming from the main nozzle below the slide port just above the throttle plate.
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User avatar
754
Posts: 96
Joined: Fri Sep 08, 2017 9:08 am
Location: Clermont Ga
Motorcycle: 1992 GL1500 Interstate

1978 CB750 Supersport

Re: '92 carb base settings

Post by 754 » Tue Mar 26, 2019 8:16 pm

I know that the main needle should not be providing fuel at idle, which is why I asked about the needle seat. I thought it very strange as well, and watched it intently for about 5 minutes and I can easily see fuel running up the needle and a few drops falling to the throttle plate. In all my years of pulling wrenches I've not seen a needle and seat not seal. I'll take it apart tomorrow and see if anything is damaged or not seated properly.
1992 Goldwing Gl1500 Interstate

1978 CB750 Supersport

User avatar
754
Posts: 96
Joined: Fri Sep 08, 2017 9:08 am
Location: Clermont Ga
Motorcycle: 1992 GL1500 Interstate

1978 CB750 Supersport

Re: '92 carb base settings

Post by 754 » Tue Apr 16, 2019 10:59 am

An update to this thread,

After stripping the offending carb no major damage or issues could be found. It sat apart on the bench for a short time due to lack of free time to put them back together. Once I got them back together and back on I decided to adjust the "choke" cable back some where it would not open as far as I had it set. That made a huge difference! After letting it warm up to temp it seems to run a bit better than before, finally it also seems that it's surge is also gone. I reassembled it yesterday and rode it for a short time, it seems to run quite well! It will need a vacuum balance and I'll get to that this week. Then it will be on to the overhaul of my CB750.

Thanks for all help everyone!

Travis


1992 Goldwing Gl1500 Interstate

1978 CB750 Supersport

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