Sync. Carburetors

[Mike D 1990 Goldwing]

I have been told by a local mechanic that I need to rebuild my carburetors and he want over $500 to do the job! I'm not looking forward to doing this because I have never done it before. I'm pretty sure I can get them off the bike but not sure I'll remember were everything goes when I put them back on. The next question is, I was watching the videos on YouTube on how to rebuild these carburetors and then one about syncing them. there is a guy that got 2 vacuum gauges from Harbor Freight and was able to sync them. Has anyone on here seen the video and if so, what do you think?? I live in Northeast Illinois, is there anyone on here that is close and could give advice on the project?
Thanks
Mike DeRohan

[WingAdmin]

You can read through this: How to sync your carburetors

The article shows me using four Harbor Freight vacuum gauges to balance the four carbs on the GL1100. However, the problem I found with those is that their calibration is TERRIBLE, and the gauges rarely match each other, which is critical when trying to balance two carbs against one another. It's also tough to get the engine pulses to stop affecting the gauges so much, which causes lots of vibration - hence the extra tubing and aquarium valves.

I long ago ditched this setup and replaced it with a Carbtune Pro carb balancer. It includes all the hoses and barb adapters you need, so the cost of the Carbtune pro is pretty close to the four Harbor Freight gauges plus tubing plus valves plus adapters that you have to buy - and it works MUCH better, with damping built in.

Find This Item on Amazon:

https://www.amazon.com/dp/B018UTHGPE?tag=goldwingdocs-20

[Mike D 1990 Goldwing]

The video I saw showed a guy syncing the 2 carbs on a 1500, and it looked like it went pretty smooth but that how a lot of those YouTube videos are, they don't show how many times they had to do something before it worked. What I liked was the price of the 2 HF gauges but if they don't work correctly then that doesn't matter. I do have one of the old stick type gauges that use mercury to measure the adjustment but they fell over and spilled some of the mercury so I have to get more, if I can? Would they be safe to use for a 1500 Goldwing? I ordered the carb kit from Randakks yesterday, but it hasn't shipped yet. I'm not going to start removing the carbs until I have everything so I can disassemble the carbs and then put them back together as soon as I can, less chance of forgetting how they go back together.
Thanks again
Mike DeRohan

[joecoolsuncle]

have you considered bench syncing? that is when you use a drill bit or a feeler gauge to sync. i prefer the drill bit, it is easy, free if you have a small drill bit, and just as accurate as vacuum gauge syncing if the gauges are not perfect, its even more accurate than gauges if they are bouncy. it can bea ss accurate as vacuum tubes (mercury) in some cases. on some engines, the recommended procedure is to do an idle drop for cable adjustment, then agin for idle mixture adjustment. has worked for many decades on such engines as bmw.

[Mike D 1990 Goldwing]

I have read about bench syncing but I don't know how to do it. Is there someplace I could get more detailed instructions on how to do them that way?

[Rambozo]

Bench syncing is just to get them good enough to install and start. Final sync is always done on a running engine.

[AZgl1800]

get a about 20 feet of clear tubing, hang it on a board, post, something.
fill it with light oil about 2/3rd the way from the bottom of the loop, stay away from water.

connect each end to a carb, and you can watch the levels in each side of the "U" loop to see the balance.

no gauges required.

you will need a couple of tiny valves, like used for misters.

[joecoolsuncle]

Bench syncing is just to get them good enough to install and start. Final sync is always done on a running engine.

yes. it is the final syncing he has trouble with.

[joecoolsuncle]

get a about 20 feet of clear tubing, hang it on a board, post, something.
fill it with light oil about 2/3rd the way from the bottom of the loop, stay away from water.

connect each end to a carb, and you can watch the levels in each side of the "U" loop to see the balance.

no gauges required.

you will need a couple of tiny valves, like used for misters.

just to add, be careful to not allow oil to be sucked into the engine, the small orifice valves will usually work well for that, and to help dampen the pulses.

[Sunshinenomad]

While a bit pricey, I now use a digi sync, especially since my Valk has 6 carbs. Not affiliated with them, just a happy user

https://thedigisync.com

[joecoolsuncle]

While a bit pricey, I now use a digi sync, especially since my Valk has 6 carbs. Not affiliated with them, just a happy user

https://thedigisync.com

lol. it says because of chip shortage....blah blah. when is the last time anyone, anywhere, say a chip in a manometer?

[WingAdmin]

While a bit pricey, I now use a digi sync, especially since my Valk has 6 carbs. Not affiliated with them, just a happy user

https://thedigisync.com

lol. it says because of chip shortage....blah blah. when is the last time anyone, anywhere, say a chip in a manometer?

It's got an LCD. That LCD needs a driver. That's one chip.
One pressure transducer per port. Those are solid state chips.
At least one ADC converter. Another chip.
Microprocessor to read the ADC and send the numbers to the LCD. Another chip.
Power supply. One more chip.

So at the very minimum there's 5-6 chips inside each one of those devices.

[joecoolsuncle]

i guess a direct readout manometer was too complicated and not accurate enough?

[Abbert55]

When I had our Valkyrie, I used clear plastic tubing, mounted to a 1/4" pegboard. Fastened the tubes with cable (zip) ties, teed it together on the bottom. 6 lines in total. Used 2 cycle oil for the balancing fluid (tried RV anti-freeze, too thin) and connected one tube to each carb. The oil will be drawn up the tube in relation to the amount of vacuum each carb is pulling. Works like a charm without costing an arm and a leg. You'll have fun making this as a project

[Mike D 1990 Goldwing]

That sounds like it works the same as the tube type synchronizer that I have, it uses mercury. It's pretty old because I used it on my 77 Kawasaki 1000.

[seelyark1]

Way back when, it's been a few years, I had a Honda 500-4 and wanted to check the sync on the carbs. I went looking around the local bike shops trying to find a manometer that would work on four carbs. Let me tell you, they were scarce at that time. Finally, I stumbled onto a motorcycle salvage yard and asked the guy where I could find one. He thought about it for a few seconds, turned around and walked into the back room and came back with a brand new one still in the box. $25 and I had one in hand. Now it uses Mercury in glass tubes, but boy is it accurate. I later had three 750-4's, and every bike I have had since had at least 2 carbs. It has been one handy tool. Now they would frown on anything that has Mercury, but it still works great.

[Abbert55]

Mercury is as they say "fun to play with, but still dangerous". The 2 stroke oil has enough viscosity that it is very stable in the tubes, and will not hurt the engine should it be injested by accident.

[Mike D 1990 Goldwing]

I have been looking for mercury online and Grainger has a 125 ml bottle for about $24 but they also want $42 for shipping. 125 ml is about 4.25 ounces. Now I'm wondering if I can replace the mercury in the tube synchronizer, I have with the 2-cycle oil mentioned in another post and is that the oil you mix with the gas? That is my assumption but that's why I'm asking, not sure. I got the carburetor kit and some of the tubing Friday still waiting for the larger size tubing.

[Abbert55]

Yes Mike, it's the 2 cycle oil you use to mix with the gas. It is colored and makes it easy to see the level in the tubes. It is thick enough as to not bounce in the tubes when the engine is running. Don't leave one side open with the other connected to the carb as this will result in the oil being injested into the engine. This will just cause your bike to instantly become a mosquito fogger for the neighborhood. Have used this method for many years with no problems and accurate balance. Basically what you are doing, is assuring the throttle slides are syncronized to be the same height/ or pulling the same amount of Vacuum (negative pressure). This assures you that one carb is not running richer or leaner than the other (provided that the same size jets are installed in each carb). Hope this helps!
Here is a link to one similar.
[YouTube]C3tXygCxtNQ.[/YouTube]
Here is another way. This one will also work with 2 cycle oil instead of water, and will work without any restrictors due to the sheer volume of the balance medium. I'm going to build one of these for my 91 SE since I let the original balancer go with the Valkyrie when I sold it.


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[seelyark1]

I believe that they now classify Mercury as a hazardous material, thus the high shipping costs. I happen to have a stash of old Mercury switches so I have spare should I need some.

[Mike D 1990 Goldwing]

I received the second shipment with the 3mm hose, so I guess I'm ready to start the teardown to get to the carburetors so I can attempt to rebuild them. Suppose to be a little warmer here in northeast Illinois but the weather person might be wrong. I'm going to change the mercury in the carb sticks I have to the 2-cycle oil and get some of the gauges mentioned earlier a little later. I'm hoping I don't need the carb holders because none of the places I checked on line have them in stock. I couldn't find any of the curved tubing that I will probably need either, I guess I'll have to see if the local dealer can get any of them. I might have some mercury if anyone needs it but you would have to live close because of the hazardous shipping thing. Before I can sell it or what ever I will have to ask my son because the carb sticks are his. Wish me luck .
Mike D

[Mike D 1990 Goldwing]

Wow, I didn't realizes it had been this long since I put an update. I got the carbs off and started the rebuild and felt like I wouldn't be able to get them back together correctly so I decided to ask the local bike mechanic if he would do them for me if I handed them to him. He told me $150 and he could do them in 2 days. That was 3 weeks ago, I have had them back for almost a week trying to get them back on the bike. I had a hard time getting them to seat all the way in the carb holders, had the leaning forwards once so I took the back out and loosened the screws on the rubber holders, finally got them in and started reassembly of the plastics. I was almost finished and trying to get the top cover with the radio on and I can't get it to set all the way down so it doesn't have a gap between it and the upper side covers that have the air and the rear speaker controls. Does anybody have any ideas what I'm doing wrong? Could be the heavy wires from the radio or maybe the carbs aren't seated as well as I thought.

[Mike D 1990 Goldwing]

Finally got it back together, still a little gap between the cover the radio is in and the covers on the side. I'm hoping when I have it out in the warm weather the plastic will be more flexible, and I might be able to get it closer. I took it for a ride last night, probably road about 20 miles and it ran really good, it idles at 800 RPM acceleration is better than it was before and it doesn't stall when I come op to a stop. The mechanic at a local repair shop called Phoenix said carbs probably won't need synchronizing, best to try it and see, they seemed fine on the 1 ride. I'm happy to have it rideable again, usually have a few short rides inn by this time of year, time to do some catching up. Thanks for all the suggestions on the synchronizing, I will still keep them in mind if it needs later.