Reinstalling/Syncing Carburetors


Information and questions on GL1100 Goldwings (1980-1983)
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shevik
Posts: 51
Joined: Sat Sep 28, 2019 2:08 am
Location: Phoenix, Az
Motorcycle: 1982 GL1100i

Reinstalling/Syncing Carburetors

Post by shevik »



Hello friends,

I recently bought an OEM carb to put on a GL1100 I found that had a sloppy single carb conversion on it.

So I opened up the OEM carb (first time I've ever opened up a carb), cleaned it up, solved some mysteries and put it back together. My question, is what do I do next before I slap this baby on my bike?

I've poked around on the internet and read a little about Bench Syncing and adjusting idle jets but it's all pretty opaque to me. Any advice, links to videos or forums, and lessons from experience would be very much appreciated. I know that I'll have to sync the carbs with vacuum guages when I get it back on the bike, but is there anything I need to do before that?

Thanks so much everyone, I posted earlier this week about a mystery inside one of the carbs when I opened it up and it was solved immediately. All of expertise around here is really making my life easier.
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If I just work hard enough I should be able to get her out and about before riding season is over.
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OldguyGlen
Posts: 226
Joined: Sat Nov 24, 2018 10:55 am
Location: Mound,MN
Motorcycle: 1980 GL1100 STD/Vetters
1966 Honda 90

Re: Reinstalling/Syncing Carburetors

Post by OldguyGlen »

Here's some brief comments. Search for other threads for more detailed step-by-step.
If the carb rack came off a running bike, it may be close to adjusted already. But that may be wishful thinking. I would hook up a temp gas supply, hanging it about 3-4 ft above the carbs to check for float valve leakage. Also check accelerator pump action getting gas to squirt to all 4 carbs. Easier to correct these items before you re-install the rack.
Start with slow jet screws at a nominal starting point... 1-1/4 turns out. These are gas jets, not air jets so CCW = more gas=richer.
Bench synch the carbs:
Set master idle screw (on the linkage) to get #3 butterfly just off the full closed position.
Adjust synch screw (between #3 and #1) so #1 matches #3 measuring with a feeler wire between butterfly edge and carb throat.
Readjust main idle screw (linkage) to get #4 just off full closed.
Adjust synch screw (between #4 and #2) to get #2 to match #4.
Adjust synch screw (aft side of #4 carb) to get #4 to match #3.
If done carefully, you are done for now. Re-install them onto the bike. Bike should start and idle. Tweak main idle screw (linkage, from the right side of bike) for 950 RPM idle. Check throttle response (idling, and under actual load at takeoff). You should find the bike runs pretty darn well already. It should be fully rideable. You can do the Vacuum Synch, and Low Jet adjust on each carb, at a later time to get the final precision tune effect.
Good luck.
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shevik
Posts: 51
Joined: Sat Sep 28, 2019 2:08 am
Location: Phoenix, Az
Motorcycle: 1982 GL1100i

Re: Reinstalling/Syncing Carburetors

Post by shevik »

Thank you so much for your reply. Could you say a little more about adjusting the butterfly vavles with a pin? I saw a post about it somewhere else but I don't really understand the method

-Dillon
If I just work hard enough I should be able to get her out and about before riding season is over.
User avatar
OldguyGlen
Posts: 226
Joined: Sat Nov 24, 2018 10:55 am
Location: Mound,MN
Motorcycle: 1980 GL1100 STD/Vetters
1966 Honda 90

Re: Reinstalling/Syncing Carburetors

Post by OldguyGlen »

Here is a video link describing a two carb setup. Technique is the same as for four carb GL1100.

How to bench sync motorcycle carbs - YouTube

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shevik
Posts: 51
Joined: Sat Sep 28, 2019 2:08 am
Location: Phoenix, Az
Motorcycle: 1982 GL1100i

Re: Reinstalling/Syncing Carburetors

Post by shevik »

This video was awesome. My carbs are now gully bench synced and ready to go back on the bike. I'll give you an update once they're on!


If I just work hard enough I should be able to get her out and about before riding season is over.
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