Carb sync quandary


Information and questions on GL1100 Goldwings (1980-1983)
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tvtruth
Posts: 25
Joined: Mon Apr 28, 2014 5:03 pm
Location: Aliso Viejo, California
Motorcycle: 1981 GL1100 naked
1987 GL1200I

Carb sync quandary

Postby tvtruth » Mon Aug 11, 2014 9:37 pm



Hi guys, I hope someone can help me out. After I have synced all 4 carbs at a well warmed up idle with a Carbtune device, I notice that if I rev the engine to 3000rpm I get quite a large disparity in vacuum between carbs 2,4 & 1,3. Any thoughts on how to eliminate the difference at that rpm. They are all equal at 950-1000 idle.



tvtruth
Posts: 25
Joined: Mon Apr 28, 2014 5:03 pm
Location: Aliso Viejo, California
Motorcycle: 1981 GL1100 naked
1987 GL1200I

Re: Carb sync quandary

Postby tvtruth » Mon Aug 11, 2014 9:55 pm

The bike is an 81 GL1100 BTW

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ct1500
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Location: Glastonbury,CT
Motorcycle: 1988 GL1500
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Re: Carb sync quandary

Postby ct1500 » Tue Aug 12, 2014 11:50 am

Any problems with the way the engine runs?
This is what I do
Local and need repair help with your 1500, Valkyrie or ST please PM

tvtruth
Posts: 25
Joined: Mon Apr 28, 2014 5:03 pm
Location: Aliso Viejo, California
Motorcycle: 1981 GL1100 naked
1987 GL1200I

Re: Carb sync quandary

Postby tvtruth » Tue Aug 12, 2014 12:01 pm

No none at all - just seemed weird that the vacuum is so different at throttle

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eklimek
Posts: 307
Joined: Tue Feb 15, 2011 1:55 pm
Location: St Catharines Ontario Canada
Motorcycle: 81 GL1100 (Widowmaker not in service), 83GL1100, CB350f x 6, CB400f x2, CB550f sold, CL350 (seized engine), plus enough donors to take me through retirement.

Re: Carb sync quandary

Postby eklimek » Tue Aug 12, 2014 12:51 pm

You may have balanced them at low rpm but higher flow amplifies a leak.

Run with it at stated rpm, then cut ignition and pull plugs. Is there a difference between left and right side?

If so time to go hunting for a vacuum leak. Poking around with a small nozzle on propane or acetylene torch might find it.

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dingdong
Posts: 2863
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Motorcycle: 1976 gl1000
1993 gl1500
2004 NRX1800 Rune

Re: Carb sync quandary

Postby dingdong » Wed Aug 13, 2014 7:28 am

Keep in mind that carb sync is an adjustment of the butterfly valve position at idle speed. Any fluctuation above idle is something else. Valve adjustment, internal carb problem, vacuum leak and the list goes on.


Tom

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