81 GL1100 Project bike: Won't Idle


Information and questions on GL1100 Goldwings (1980-1983)
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dustinabono
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81 GL1100 Project bike: Won't Idle

Postby dustinabono » Mon Apr 11, 2011 8:33 pm



Finally started my project bike today after installing a new set of carburetors, it'll start and run but dies if I let the rpms drop below about 1500. What should I do next?



MIDTOP
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Re: 81 GL1100 Project bike: Won't Idle

Postby MIDTOP » Tue Apr 12, 2011 11:18 am

I have the same problem right now. I cleaned carbs, runs smooth above 2000rpms, then dies under 1500rpms.

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thrasherg
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Re: 81 GL1100 Project bike: Won't Idle

Postby thrasherg » Tue Apr 12, 2011 11:36 am

Are the idle mixture screws set correctly? and the idle jets are clean? Is the timing set correctly and is your vacuum advance working correctly?

Gary

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virgilmobile
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Re: 81 GL1100 Project bike: Won't Idle

Postby virgilmobile » Tue Apr 12, 2011 11:58 am

A new set of carbs?They may not have been static adjusted for fuel flow,idle metering,etc.Speculations are....vacuum leak at the "O" rings(I forgot to put them in once :mrgreen: ),rubber couplers not tightened(I did that once too)floats set wrong(not enough gas for the idle circuit)idle mixture screw tightened all the way in.I guess that if it stops firing below 1500 rpm,the idle circuit is not providing fuel from the front port.Either it's plugged,no fuel available,or not enough vacuum to suck it out to the cylinder.

dustinabono
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Re: 81 GL1100 Project bike: Won't Idle

Postby dustinabono » Tue Apr 12, 2011 12:51 pm

Thanks for the suggestions. I hope that the guy who rebuilt these carbs knew what he was doing, so I think I'll start with things that don't require me to open them up. How do I check & adjust the timing? And where are the idle mixture set screws? Also, do you think I should try to adjust the pilot screws?
Thanks again

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virgilmobile
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Re: 81 GL1100 Project bike: Won't Idle

Postby virgilmobile » Tue Apr 12, 2011 1:10 pm

Idle mix adjustment and pilot screws are the same.Turn out from bottom about 1.5 turns.they are on the bottom outside of the bowl.Did you use new "O" rings?I doubt that timing would have been changed from sitting,but the vacuum advance mechanism could be sticking.Check it later.Even with the timing off it should fire all the way down to a stall,not die below 1500 rpm.If I remember,the bowl holds about a shot glass of gas.Drain 1 carb and see how much gas is in there.Maybe somebody knows the oz. amount.It still sounds like there's enough fuel for the main jet but none getting through the idle port.

dustinabono
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Re: 81 GL1100 Project bike: Won't Idle

Postby dustinabono » Tue Apr 12, 2011 1:20 pm

OK, thanks for the clarification. We bought the carbs rebuilt online, I hope he used new O rings. Just read in the service manual that the timing is not adjustable, guess I'll just check it. I'll try adjusting the pilot screws this weekend along with the idle speed. Hope I don't have to take the carbs apart, didn't have very good luck with my first set. Haven't checked compression on the bike yet either, think that might have anything to do with it?

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virgilmobile
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Re: 81 GL1100 Project bike: Won't Idle

Postby virgilmobile » Tue Apr 12, 2011 1:26 pm

A few minutes in the web resulted in this info.."Fuel volume on the GL1200s is about 36 - 42 CC, I don't recall the exact number, and it depends on the engine and condition of the slide diaphragms. I initially tuned these floats by setting the tangs in 0.020" increments and doing statistical measurements of corresponding bowl volumes, it DOES make a big difference, unless one doesn't care that the engine runs poorly. Most people never stumble onto tuning like this to know that it makes a difference - they wouldn't believe it unless they saw it. "I Googled.."gl1100 carb fuel capacity".The numbers should be close enough to get a starting point.If you only have 2 tablespoons of gas,that's your problem.If the fuel is plentiful,look for a common vacuum leak or a poor rebuild.

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virgilmobile
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Re: 81 GL1100 Project bike: Won't Idle

Postby virgilmobile » Tue Apr 12, 2011 1:36 pm

The "O" rings I refer to are between the turn-down(intake) tubes and the head(you would install them).A engine needs at least 85 psi compression to ignite gas effectively.Generally a poor idling engine would be near 90-100 psi.Honda say the service limit it 145 psi with no more than 4-5 psi difference.Even at 100 psi,it should idle somewhat.

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virgilmobile
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Re: 81 GL1100 Project bike: Won't Idle

Postby virgilmobile » Tue Apr 12, 2011 1:40 pm

I also hope that your "rebuilt carbs" were actually rebuilt and not just cleaned up.

dustinabono
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Re: 81 GL1100 Project bike: Won't Idle

Postby dustinabono » Wed Apr 13, 2011 1:14 am

I hope so too. I did use new O rings on the intake tubes. Can I open the carb and drain the bowl without removing the entire carb assembly from the bike? If I can then I should be able to check that this weekend too. Thanks again.

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virgilmobile
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Re: 81 GL1100 Project bike: Won't Idle

Postby virgilmobile » Wed Apr 13, 2011 11:09 am

I used some aluminum foil and shaped it into a channel under the carb,opened the drain plug and drained it into a glass.Marked the level and drained each one to see.




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