GL1000: No vacuum on right bank after carb rebuild

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RasmusTJ
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GL1000: No vacuum on right bank after carb rebuild

#1

Post by RasmusTJ »

Hi forum!

I'm experiencing an odd thing after rebuilding the carburetors on my '76 GL 1000. When I started it, it climbed up to an idle of 3.000 rpm, which I have read is common prior to synchronizing.

What I find odd is that there is no vacuum on the right bank (no. 1 and 3 - which is the reference carb). This must be what is leading to the high idle, but I can't adjust the reference carb. I've tried spraying starting fluid around the intakes to find leaks with no noticeable difference. Have anyone tried anything similar?

I have of course adjusted the ignition and valves and ensured proper compression etc. prior to start up. As of now I'm afraid I will have to disassemble the carbs once again - even though I don't know what I could have done wrong. The floats are adjusted and there is no overflow. I have set the idle mixture screws 2 turns out.

I am eagerly seeking help, so I am trying to reach out to you experts on the forums where I have previously found great advice.

Thanks in advance,
Rasmus
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wingrider
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Re: GL1000: No vacuum on right bank after carb rebuild

#2

Post by wingrider »

Welcome to the forum! Is this Wing new to you, or have you had it a while? A little info in the introduction area would be nice.

If it is new to you, you say that you have adjusted the valves, and ignition. Did you by chance do a compression check to see what you have on all cylinders? Did you change the belts by chance?
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ericheath
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Re: GL1000: No vacuum on right bank after carb rebuild

#3

Post by ericheath »

If you didn't do it, a bench sync is a good thing to try without having to remove the rack. Some use a very small wire or feeler gauge under each butterfly to get them equal. A danger to the wire is tightening too hard on them and leaving a groove in the butterflies. I sync mine by trying to leave just half of the first of the three small holes in the throat showing. Seems to get it close, keeps the idle low, and doesn't risk hurting the butterflies.

You could also double check your belt timing marks.
Whatever I suggest here should be given ample time for a moderator to delicately correct. I apologize in advance.
77 WING, 1200 engine with 77 heads, cams, gl1100 foot pegs, Magna V65 front end, 764A carbs, [-gone Suzuki M109 monoshock--, replaced with gl1100 shocks] gl 1200 swing arm, gl1500 final drive, wheel and rear brakes Valkyrie seat, Meanstreak tank, Sportster pipes, Power Arc ignition off crank.
77 Wing. black
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"Continuing education is important even if the subject matter is fairly useless (as in this case)."---Greg Foresi
RasmusTJ
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Re: GL1000: No vacuum on right bank after carb rebuild

#4

Post by RasmusTJ »

Thanks for the replies, guys.

I've had it for half a year, restoring mainly the mechanical parts including new original ignition plate, carb rebuild, spark plugs and timing belts/tensioners to name some of the things which may impact the problem.

The carb rebuild was done by total disassembly and ultrasonical cleaning of all parts, with new tourmax kits to replace all gaskets, o-rings and cut off valve. I've triple checked the timing marks, as a step of common troubleshooting.

Thanks for the tip on the bench butterfly synchronization - I will definitely try that as I hadn't thought of that at all!
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Re: GL1000: No vacuum on right bank after carb rebuild

#5

Post by olchris »

Hi and welcome from Aust....... I see your from Denmark and as we are from the 4 corners of the world different words have different meanings as you are aware of. Me, i am not sure what you mean by "no vacuum right bank"....

As previously suggested a "rebuild" of carbs will always require a sync or balancing of carb vacuum, which is impossible to do by ear... you need to use a set of 4 gauges to acheive a good result...

There are many posts on NGW refering to similar/same problems your experiencing...........

I dont know how long you have looked at NGW but you will need to read ...

http://www.ngwclub.com/forum/viewtopic.php?t=3626 and further info is also availabe..

Some of the home made recipes for pasta are not worth viewing but mostly all tips are good....

http://www.ngwclub.com/shoptalk/
1972 Norton.. Rebuild from boxes.. http://www.accessnorton.com/strange-fra ... 44-60.html and here http://www.accessnorton.com/strange-frame-t18084.html SOLD
1975 Mk3 Norton.. Too good to mess with, but refurbished...
1975 Goldwing #1 SOLD
!975 Goldwing #2.. http://www.ngwclub.com/forum/viewtopic. ... 2+wing%232
1975 Goldwing #3... http://www.ngwclub.com/forum/viewtopic. ... =Wing+%233 Going very slowly but going forward..
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ericheath
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Re: GL1000: No vacuum on right bank after carb rebuild

#6

Post by ericheath »

My experience with TourMax carb kits is absolute total JUNK!!!! The float bowl gaskets swell as soon as they come in contact with fuel. Mine would swell up so much they would keep the floats from moving. Take the bowls off and it would show them all swollen. Fifteen minutes later, they would shrink and look like new. I don't know if the orings and such are the same, but they belong in the garbage. If you used their brass, I hope you saved the old brass. There is a good write up comparing carb kits in Shoptalk by Roncar. It's probably worth a read.

It's hard to imagine 3000 rpm and no vacuum, but this bikes can idle deceptively smooth on just three cylinders. Checking exhaust temp at the header can be revealing. Use a spray bottle of water and quickly squirt and compare how quickly it dissipates. A weak firing cylinder will be cooler.

Don't mean to alarm you on the carb kits, but that's what I found. No wonder they were selling on EBay for $10 each.
Whatever I suggest here should be given ample time for a moderator to delicately correct. I apologize in advance.
77 WING, 1200 engine with 77 heads, cams, gl1100 foot pegs, Magna V65 front end, 764A carbs, [-gone Suzuki M109 monoshock--, replaced with gl1100 shocks] gl 1200 swing arm, gl1500 final drive, wheel and rear brakes Valkyrie seat, Meanstreak tank, Sportster pipes, Power Arc ignition off crank.
77 Wing. black
83 Wing, in pieces
"Continuing education is important even if the subject matter is fairly useless (as in this case)."---Greg Foresi
RasmusTJ
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Re: GL1000: No vacuum on right bank after carb rebuild

#7

Post by RasmusTJ »

Hey olchris, thank you and sorry for the confusion. I have the Morgan Carbtune (mercury filled tubes) for the gauge sync and it showed very low vacuum when the motorcycle was fired up. I have read some of the threads you mention, but I got worried when I experienced low vacuum on the reference carb.

Erik, you might be right. I guess I didn't expect that the rubber parts could be THAT rubbish - I mean, they should just secure a proper seal and that's it. I reused the old (original) brass parts and did use the excellent carb kit guide which primarily warned about the metal parts of aftermarket kits as I remember. I have checked the headers and they all four fire - some possibly a bit weaker than others.

I will give it a go tomorrow and report back the findings. Thanks for sharing your knowledge, guys. :)
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Re: GL1000: No vacuum on right bank after carb rebuild

#8

Post by olchris »

With a little thought today i wondered if your Mercury balance gauge set is doubtful/wrong.......... Calibrated??? Do you have access to another bike that runs OK so that you can test each vac gauge independantly to ensure they all work and read the same, because they should on the same carb......

gotta check the checking equipment!!!
1972 Norton.. Rebuild from boxes.. http://www.accessnorton.com/strange-fra ... 44-60.html and here http://www.accessnorton.com/strange-frame-t18084.html SOLD
1975 Mk3 Norton.. Too good to mess with, but refurbished...
1975 Goldwing #1 SOLD
!975 Goldwing #2.. http://www.ngwclub.com/forum/viewtopic. ... 2+wing%232
1975 Goldwing #3... http://www.ngwclub.com/forum/viewtopic. ... =Wing+%233 Going very slowly but going forward..
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Re: GL1000: No vacuum on right bank after carb rebuild

#9

Post by robin1731 »

olchris wrote:With a little thought today i wondered if your Mercury balance gauge set is doubtful/wrong.......... Calibrated??? Do you have access to another bike that runs OK so that you can test each vac gauge independantly to ensure they all work and read the same, because they should on the same carb......

gotta check the checking equipment!!!

The nice thing with mercury type gauges is they don't need to be calibrated like the round dial type gauge. As long as the tubes are all in line that is all you need. They do have restrictors in the line, just like the round type. And those restrictors should be closer to the carb than to the gauge.
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ericheath
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Re: GL1000: No vacuum on right bank after carb rebuild

#10

Post by ericheath »

My last set of mercury gauges had the tubes develop hairline cracks in the plastic rendering them useless. Examine yours carefully.
Whatever I suggest here should be given ample time for a moderator to delicately correct. I apologize in advance.
77 WING, 1200 engine with 77 heads, cams, gl1100 foot pegs, Magna V65 front end, 764A carbs, [-gone Suzuki M109 monoshock--, replaced with gl1100 shocks] gl 1200 swing arm, gl1500 final drive, wheel and rear brakes Valkyrie seat, Meanstreak tank, Sportster pipes, Power Arc ignition off crank.
77 Wing. black
83 Wing, in pieces
"Continuing education is important even if the subject matter is fairly useless (as in this case)."---Greg Foresi
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