Vacuum


Information and questions on GL1100 Goldwings (1980-1983)
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oldie61
Posts: 4
Joined: Mon Jun 15, 2015 9:14 pm
Location: kingston,ontario,canada
Motorcycle: 1981 honda goldwing gl1100, and 1982 yanaha virago 750

Vacuum

Post by oldie61 »



Hello, my 1981 gl 1100 is idling rough to not at all under 1000rpm. I just hooked up vacuum gauges and was shocked to find no vacuum at idle or above on #1 cylinder, have 0-40 oscillating at hand held idle with throttle at 1000rpm. I was xonsiderjng synching catbs but of course I need vacuum at all cylinders to do this. Bike seens to run fine above idke lije riding etc.
Suggestions where to start and investigate for no vacuum?
Thanks


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oldie61
Posts: 4
Joined: Mon Jun 15, 2015 9:14 pm
Location: kingston,ontario,canada
Motorcycle: 1981 honda goldwing gl1100, and 1982 yanaha virago 750

Re: Vacuum

Post by oldie61 »

Correction/amendment to my post on vacuum, I found the problem of no vacuum on #1 cylinder. It was a plugged fitting in the brand new vauum gauges I recently ordered online. Must have been an epoxy/sealant used when the tube and fitting were asembled. Cleared it out with a drill all good now. I had tried another
Fitting that came with the set.
So vacuum issue all good.
I just have to determine why I have a lumpy idle (actually I have to hold throttle around 1000rpm) and its still quite lumpy. Bike starts real good so timing doesnt seem to be an issue.
I've heard here or on similar forums about carbs being out of sync causes similar idling issues as well as sounding like a bearing knock.
This is what i have.
gerald collins
Posts: 15
Joined: Wed Jan 20, 2016 5:42 am
Location: atlanta, Georgia
Motorcycle: 1983 GL1100 Interstate

Re: Vacuum

Post by gerald collins »

Hi, I'm restoring an 81, and after cleaning the carbs it sounded like it was going to destroy itself with knocking. I decided to take the carbs to a real mechanic, and after his professional cleaning, it ran like a jewel. So, I would guess your carbs are dirty. Gerald in Atlanta
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OldguyGlen
Posts: 227
Joined: Sat Nov 24, 2018 10:55 am
Location: Mound,MN
Motorcycle: 1980 GL1100 STD/Vetters
1966 Honda 90

Re: Vacuum

Post by OldguyGlen »

Suspect you have more than a sync issue. Rough to no idle capability at or below 1000 rpm probably means the low speed circuits in the carbs are clogged.
Set it to idle as slow as practical. Try to test exhaust pipe temperature on each cyl. (don't burn yourself). Try removing plug wire, one at a time. Try adjusting idle fuel screws, seeing if it has no effect on some cylinders. You are looking to see if one or more cylinders are not contributing their equal share to the idle condition. That usually means carb trouble on that cyl. Many DIY carb cleaning efforts still fails to get the low speed circuits really clean. Search for other carb clean threads for more info. While the carbs are off the bike for cleaning, do a careful job of bench syncing them before re-install. That should get you close. In fact that should get you so close that vacuum syncing can be put off till later 'cause the bike will run pretty darn well anyway. You can't vacuum sync a set while some individual carbs are still plugged up.
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tigercub
Posts: 51
Joined: Sat Oct 13, 2018 5:06 pm
Location: ontario
Motorcycle: 1980 gold wing interstate gone naked
1972 CL350
1968 Triumph TRW250
1954 Triumph Tiger Cub

Re: Vacuum

Post by tigercub »

I had to do a carb rebuild on my 1980. It was really hard to clean the pilot jets but after removing them and cleaning, and bench syncing it ran quite well on idle. Syncing the carbs was hardly needed, but made it run even smother.


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