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Discussion Starter · #1 ·
I've had an 82 GL500 for awhile now and thought I had a persistent problem with one of the carbs. I got a second carb set with an engine I bought and rebuilt them. After installation and checking, the engine still had the same problem. Id twist the throttle a little and the engine would at first hesitate and then rev. When I released the throttle, the engine continued to rev even with no throttle. Eventually the revs would drop back down to idle. After some thinking, I'm beginning to believe the problem might be a sticking ignition advance. I haven't pulled that off yet to check it because I wanted to find out if anyone had a similar problem?
 

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Yes, in my case it turned out to be how the throttle cables were routed. Rerouted as shown in the factory service manual and the problem was gone.
 

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Discussion Starter · #3 ·
Yes, in my case it turned out to be how the throttle cables were routed. Rerouted as shown in the factory service manual and the problem was gone.
I checked the cables. Thought that might be the problem and it wasn't. Come up with any other ideas before I remove the advance, let me know.
 

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I checked the cables. Thought that might be the problem and it wasn't. Come up with any other ideas before I remove the advance, let me know.
Make sure the sliders in the carbs are moving freely up and down.
 

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Have you checked for air leaks between the carb and head?
 

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Have you checked for air leaks between the carb and head?
Agreed, high hanging idle often means too lean. Maybe due to air leak, maybe due to float height set incorrectly.
 

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Discussion Starter · #8 ·
Have you checked for air leaks between the carb and head?
Yep, check for leaks on both ends of the inlets. Did not show a problem there. I checked the advance and that is not it. After reassembly and re-setting the timing, started it up with the air cleaner off. Same problem persist. I will check over the other carbs I rebuilt and perhaps remount them and see if they have they do have the same problem. If so, might look into getting one of the carb manuals listed and see if I'm not putting them together correctly.
 

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Discussion Starter · #9 ·
Agreed, high hanging idle often means too lean. Maybe due to air leak, maybe due to float height set incorrectly.
Checked for air and vacuum leaks. Ran it without the air cleaner. Checked spark plugs and they did not show any sign of running lean. When I put the original carbs back on, made sure they were both timed together. It might possibly be a choke problem, but not certain at this point.
 

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Aside from wrong jets, here are a few of the more obscure things that can cause high idle or weird air/fuel mixture that I've encountered working on various GL/CX's:
  • float height measured when carbs fully upside down rather than just barely engaging the valve plunger
  • tear in the air cutoff valve diaphragm. It took a while to find this one.
  • torn intake manifold gasket or oring
 

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82 GL500, 78 CX500
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Discussion Starter · #11 ·
Aside from wrong jets, here are a few of the more obscure things that can cause high idle or weird air/fuel mixture that I've encountered working on various GL/CX's:
  • float height measured when carbs fully upside down rather than just barely engaging the valve plunger
  • tear in the air cutoff valve diaphragm. It took a while to find this one.
  • torn intake manifold gasket or oring
I will do what you suggest. I also ordered Larry's Carb Manual. I'll post how things proceed.
 

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I will do what you suggest. I also ordered Larry's Carb Manual. I'll post how things proceed.
Good luck with them. Carbs are a source of constant learning
 
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