Idle problem


Information and questions on GL1200 Goldwings (1984-1987)
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ejohnw
Posts: 5
Joined: Mon Apr 27, 2015 7:12 pm
Location: United States
Motorcycle: 85' GL1200 Interstate

Idle problem

Post by ejohnw »



Over the Winter months I replaced the push and pull throttle as well as the choke cables on my 85' GL1200 I. Now after starting and the engine warming up, the idle RPM will occasionally shoot from it's normal 650 to run up to over 3000. This will also occur while I am riding and come to a stop, or engage the clutch. I have checked that the throttle down on the carborator body and it's returning and stopping properly to the throttle adjustment screw. The cables do not appear to be dragging or too tight either.

The choke cable also appears to be moving freely.

Any thoughts?



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Aussie81Interstate
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Joined: Thu Nov 27, 2014 2:34 am
Location: Penrith Australia
Motorcycle: 2001 GL1500F6C Valkyrie
1982 CX500 Turbo (Historic registration - finally)
1981 GL1100 Interstate (sold)
1988 GL1500 (sold)

Re: Idle problem

Post by Aussie81Interstate »

Sounds like they need some lubrication - or could it be the throttle tube is binding ?

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ekvh
Posts: 409
Joined: Thu Apr 29, 2010 9:52 am
Location: Grand Forks, ND
Motorcycle: 1977 gl1000

Re: Idle problem

Post by ekvh »

If the linkage is returning to the stops, that rules out sticky cables and tubes. The 1200's also have a starter valve instead of a choke. It opens to allow extra fuel to be drawn in by vacuum much like an additional jet. Sometimes the valves can stick. The valve actuating mechanism runs horizontally on the outside part of the carb. They are held in place by a black plastic locknut with a hole through it for the starter valve. Check to see that it is freely returning to its closed position.

If this is the issue, they can be removed and cleaned. Pay attention to the spring and small stainless steel washer. The washer can drop and garage monkeys love to eat them.

I had one that would hang open enough to cause the issue.

Your description sounds also like a vacuum leak. You can wave an unlit propane torch around the elbows and carb to locate it/them while at idle. If you have a leak, the vacuum will pull the propane in and cause the motor to rev up some.

It's easy to have a rubber elbow to leak due to a clamp too loose.

ejohnw
Posts: 5
Joined: Mon Apr 27, 2015 7:12 pm
Location: United States
Motorcycle: 85' GL1200 Interstate

Re: Idle problem

Post by ejohnw »

Thanks ekvh and Aussie, I think the cables are not an issue here they are all moving freely and the throttle adjustment screw is always against the stop when the condition happens. To ekvh, the choke cable seems to only have about 3/4 to 1 inch of motion. Since the choke cable was probably not functioning properly for as long as I have owned the bike (2 years) I don't know if this is the normal feel at the handle bars. Also isn't there any spring to return that valve (choke) to closed?

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ekvh
Posts: 409
Joined: Thu Apr 29, 2010 9:52 am
Location: Grand Forks, ND
Motorcycle: 1977 gl1000

Re: Idle problem

Post by ekvh »

If you have the carb chrome covers, remove them so you can see the choke (cold start valves) operate when you push and pull the lever. You will see the brass end poking out of the black plastic nut. After you've pushed the "choke lever" off, see if you can push any of the brass ends into the carburetor. You should not be able to push them in. They should move freely in and out as you operate the lever.

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ekvh
Posts: 409
Joined: Thu Apr 29, 2010 9:52 am
Location: Grand Forks, ND
Motorcycle: 1977 gl1000

Re: Idle problem

Post by ekvh »

Pics are worth a grand, but this website won't let me add pics from my iPhone.

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ekvh
Posts: 409
Joined: Thu Apr 29, 2010 9:52 am
Location: Grand Forks, ND
Motorcycle: 1977 gl1000

Re: Idle problem

Post by ekvh »





The bottom pic shows what you'll see on the carb. The top blue arrow shows where it may be hanging open. They will come out and apart to clean but it's a pita taco to twist and turn everything just right to do it. Reassembly is as much fun at least. Lots of small nuts, washers, plastic inserts on the linkages.

ejohnw
Posts: 5
Joined: Mon Apr 27, 2015 7:12 pm
Location: United States
Motorcycle: 85' GL1200 Interstate

Re: Idle problem

Post by ejohnw »

I found the pictures of the valve in the repair manual contained on this site too. Thanks again for your knowledgeable answers.



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