carbs 1990 gl1500 se piston vacuum and syncing


Information and questions on GL1500 Goldwings (1988-2000)
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Bubbamer
Posts: 3
Joined: Tue Aug 26, 2014 8:30 pm
Location: Chestermere Alberta Canada
Motorcycle: Candy red 04 gl1800
Pearl white 90 gl1500se
3- 1983 aspencades

carbs 1990 gl1500 se piston vacuum and syncing

Postby Bubbamer » Wed Oct 01, 2014 12:50 pm



I recently aquired a 1990 GL1500 SE that had been improperly stored for 3-4 years. needless to say that when we went to start the unit (after new gas) gas poured out of the overflow pipes due to stuck float valves. I removed the carbs and cleaned out the guck inside. I also examined the slide piston vacuums only to find holes in the diaphragms. I replaced these at a price of $155.00 each (not including the needle valves) from mother Honda. When I removed the needle valves from the old slide pistons I neglected to note the position of the small notches (approximately 1/8 of the circumference) on the disc in relation to the top or bottom of the piston as it is in place in the carb. The disc is a one piece two tiered round disc with a small piece cut out of the circumference of each tier opposite each other (180 degrees). The disc and needle valve are secured in place by a quarter turn of the disc.
My first question is: When looking inside the piston from the diaphragm side, does it matter whether or not the notch in the visible part of the disc is on the top or the bottom of the slide piston?
Next question: Is syncing and balancing the carbs the same thing? Can the carbs be balanced or synced off the bike? How do you sync/balance the carbs on the GL1500SE?
Pictures and/or video would be excellent if available.
Because I am new to this site I am unsure of how to retrieve pictures or videos relating to the 1990 GL1500SE.
I would appreciate any help in this matter.



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Mh434
Posts: 944
Joined: Tue Mar 25, 2014 10:24 pm
Location: Victoria, British Columbia, Canada
Motorcycle: 1997 gl1500 SE
Previous:
1981 GL1100I
1989 Kawasaki Concours

Re: carbs 1990 gl1500 se piston vacuum and syncing

Postby Mh434 » Wed Oct 01, 2014 1:49 pm

WOW!! $155 EACH?? Holy smokes, that's painful! Now I understand why some have repaired holes in their diaphragms with liquid electrical tape or Plasti-Dip!

Balancing the carbs (synching, same thing) requires the use of a carb balancer. Generally speaking, carb balancing is the process of releasing the throttle linkage where it joins the carb throttles together, adjusting the vacuum of each carb so they're the same, then re-connecting the linkage between them. In this way, all cylinders get near-identical fuel, vacuum, etc., so that the engine runs smooth. The carb balancer is nothing more than a set of vacuum gauges, one of which attaches to each carb. Note that the engine has to be running, and at proper running temperature, to do this!

Back in the day, I used to balance multiple carbs on bikes & cars just using a length of rubber tubing up to my ear, the other end at a carb throat, and listening to the hiss of the air going through each throat. It was possible to get very, very close that way, but then, carbs were much simpler back then & there weren't any emissions controls etc. to affect the outcome. And, it took a fair bit of practice to become skilled at it.

You might want to check around to see if someone you know has a balancer. They're not horrendously expensive (anywhere from $35-$100), but then again, unless you're working on multi-carb engines frequently, they're not something you're likely to use again anytime soon, so a borrowed one just might do the trick.

Another option is the DIY-route. LOTS of people have had great success with building their own balancers (a Google search will turn up lots of ideas) with bits of stuff they have lying around. These can work very well, if carefully constructed & used.

This is the one I have - not expensive (around the $75 mark) - also, a Youtube video of these in use, balancing a GL1500 engine...



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Bubbamer
Posts: 3
Joined: Tue Aug 26, 2014 8:30 pm
Location: Chestermere Alberta Canada
Motorcycle: Candy red 04 gl1800
Pearl white 90 gl1500se
3- 1983 aspencades

Re: carbs 1990 gl1500 se piston vacuum and syncing

Postby Bubbamer » Wed Oct 01, 2014 6:04 pm

Thanks mh434 for the reply. The carb sync looks to be a piece of cake with the proper equipment. I was uncertain where the adjusting screw was but it turned out to be the one that I though it was.
My big concern is the correct position of the locking disc inside of the slide piston when looking at it from the diaphragm end as to whether or not it matters if the notch should be up (in the 12 oclock position) or down (6 oclock position)or does it matter. I would hate to install the carbs only to find that it does matter.
Are there any expert carb mechanics who can give me a definative answer regarding this issue. PLEASE HELP. Thanks to everyone in advance.

User avatar
Mh434
Posts: 944
Joined: Tue Mar 25, 2014 10:24 pm
Location: Victoria, British Columbia, Canada
Motorcycle: 1997 gl1500 SE
Previous:
1981 GL1100I
1989 Kawasaki Concours

Re: carbs 1990 gl1500 se piston vacuum and syncing

Postby Mh434 » Wed Oct 01, 2014 11:51 pm

Unfortunately (or, fortunately, for me!), I haven't had my carbs apart, so I don't know the answer to the discs quandary. I suspect WingAdmin or one of the other pros will be along shortly with a definitive answer, though.

Bubbamer
Posts: 3
Joined: Tue Aug 26, 2014 8:30 pm
Location: Chestermere Alberta Canada
Motorcycle: Candy red 04 gl1800
Pearl white 90 gl1500se
3- 1983 aspencades

Re: carbs 1990 gl1500 se piston vacuum and syncing

Postby Bubbamer » Tue Oct 07, 2014 6:44 am

Thanks for your response mh434. I found a grey haired Honda mechanic and posed the question regarding the position of the disc when installing the needle valve into the slide piston diaphragm. He stated that it did not matter cuz it will only go in one was. I guess that I must have installed them correctly cuz the both won't in easily.
I reinstalled the carbs, what a job without new rubber collars, anyway I flames her up and she ran like a kitten.
This sure is a great site and have used it for, timing belts, wheel removal etc.
It appears that the carbs are in balance already as she runs so well but wil, check them anyway.
Thanks to all




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