running rich at idle


Information and questions on GL1200 Goldwings (1984-1987)
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jtimgrant
Posts: 77
Joined: Sat May 25, 2013 7:24 am
Location: Greensboro NC.
Motorcycle: 1987 GL1200 Aspencade

running rich at idle

Postby jtimgrant » Mon Jun 17, 2013 10:20 am



My 87 aspy runs/smells rich at idle. Highway operation seems perfect. 48 mpg and smooth. Here is what I've done thus far. Replaced the timing belts. Cleaned carb bowls/jets. Adjusted float level. Replaced slow air control valve (it was leaking). Replaced vacuum lines. Sync'd carbs. All seemed well until I took a 500 mile trip. In 200 miles the bike dropped 150 rpm's and smelled very rich. Spark plugs look perfect. I do have an exhaust leak. The choke lever also seems stiff as if one of the starters is sticking but they all look seated.

Here are things that cross my mind:
1. Would the exhaust leak cause the rich conditions?
2. Could be carb sync be off again?
3. Could the charging voltage be dropping at idle causing weak spark? Wouldn't that cause wet or sooty plugs?
4. Trash in jet or needle valve?

Tim



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virgilmobile
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Motorcycle: 1988 GL1500 I
Previously owned
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Re: running rich at idle

Postby virgilmobile » Mon Jun 17, 2013 11:31 am

Only thing you forgot.The idle down adjustment.
Often this overlooked and needs to be done on a the bike after the service you've done.
Mine were fine for a factory fresh bike but needed fine tuning when I serviced it with 50k miles.
I did have to drills small hole in the cap and use a sheet rock screw to remove the cap to acess the mix screws.I preset as per the manual for a starting point then tweaked just a little.
The factory had mine set from 1 turn out to 4 turns out.

jtimgrant
Posts: 77
Joined: Sat May 25, 2013 7:24 am
Location: Greensboro NC.
Motorcycle: 1987 GL1200 Aspencade

Re: running rich at idle

Postby jtimgrant » Mon Jun 17, 2013 1:08 pm

Thanks Virgilmobile. Decided to pull the spark plug wires while running. No change at all on #3. It's dead at idle. Good fire. Plugs good. Switched plug wires between 1 and 3 to test for bad wire. Still dead at 3. Runs richI will check the compression shortly. And the saga continues.

Tim

jtimgrant
Posts: 77
Joined: Sat May 25, 2013 7:24 am
Location: Greensboro NC.
Motorcycle: 1987 GL1200 Aspencade

Re: running rich at idle

Postby jtimgrant » Mon Jun 17, 2013 1:49 pm

Compression check done. 152 psi. Looks like the carbs are coming back off.

Tim

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virgilmobile
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Motorcycle: 1988 GL1500 I
Previously owned
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83 GL1100 I
83 GL1100 standard
84 GL 1200 I

Re: running rich at idle

Postby virgilmobile » Mon Jun 17, 2013 2:03 pm

No fire at a idle indicates in your case either a plugged slow speed circuit or a bad sync.
The "dead at idle cylinder" would be pulling a much higher vacuum if it's just synced wrong.
If the vacuum is close,the idle circuit is first suspect.
While your there, pop the cover caps off the idle mix jet hole so you can get to adjust them.
I've got a post somewhere here on my carb service that showed how I did it if you need more info and pictures.
I also had a stutttter around 2k rpm that I cured by lifting the main needles wirh a washer.
Here's the post....viewtopic.php?f=5&t=9179

jtimgrant
Posts: 77
Joined: Sat May 25, 2013 7:24 am
Location: Greensboro NC.
Motorcycle: 1987 GL1200 Aspencade

Re: running rich at idle

Postby jtimgrant » Mon Jun 17, 2013 4:08 pm

Thanks Virgil. I've got to pick up some 5mm vacuum adapters to check the sync. I'm suspect its the sync.

More to come . . . I'm sure.

Thanks again

Tim

jtimgrant
Posts: 77
Joined: Sat May 25, 2013 7:24 am
Location: Greensboro NC.
Motorcycle: 1987 GL1200 Aspencade

Re: running rich at idle

Postby jtimgrant » Mon Jun 17, 2013 6:55 pm

Carb's are in sync. Engine runs perfect past 1500 rpms. Compression is 155 psi at each cylinder. Tomorrow I will follow Virgil's recommendation and remove the pilot screw.

Tim

jtimgrant
Posts: 77
Joined: Sat May 25, 2013 7:24 am
Location: Greensboro NC.
Motorcycle: 1987 GL1200 Aspencade

Re: running rich at idle

Postby jtimgrant » Mon Jun 17, 2013 7:50 pm

Decided not to wait. Pulled the pilot screw. All looked fine. Screw was set at 2 turns. Turning the screw makes no difference in rpm as manual states it should. So let's summarize:

Motor runs rich. Number 3 cylinder is dead at idle. Motor runs good above 1500 rpms. Pulling plug wire makes no difference. I switched number one and three wires to test number 3 wire with no change. I plugged a new spark plug in number 3 and firing appears strong.

Thanks for helping.

Tim

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virgilmobile
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84 GL 1200 I

Re: running rich at idle

Postby virgilmobile » Tue Jun 18, 2013 6:59 am

Your slow speed pathway/jet circuit is plugged.That dead at idle cylinder is only getting gas from the main jet.

jtimgrant
Posts: 77
Joined: Sat May 25, 2013 7:24 am
Location: Greensboro NC.
Motorcycle: 1987 GL1200 Aspencade

Re: running rich at idle

Postby jtimgrant » Tue Jun 18, 2013 7:09 am

Thanks Virgil. I'm taking the carbs back off tonight. I can hardly wait. :lol:

Tim

jtimgrant
Posts: 77
Joined: Sat May 25, 2013 7:24 am
Location: Greensboro NC.
Motorcycle: 1987 GL1200 Aspencade

Re: running rich at idle

Postby jtimgrant » Tue Jun 18, 2013 11:09 pm

Removed the carbs tonight and recleaned number 3. Cylinder is now firing. Thanks Virgil.

Now I can't seem to get the intake tubes to stop leaking. There were no vacuum leaks until I removed the carbs tonight. The o-rings were put on when I did the carbs a couple weeks ago. Is it necessary to replace them each time the tubes are removed? I sprayed starting fluid around them and the engine responds at numbers 1 and 3. Has anyone used rtv along with the orings?

Again, thanks for the help.

Tim

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virgilmobile
Posts: 7649
Joined: Sun Sep 19, 2010 5:39 pm
Location: Denham Springs,La.
Motorcycle: 1988 GL1500 I
Previously owned
78 GL1000
81 GL1100
82 GL1100 I
83 GL1100 I
83 GL1100 standard
84 GL 1200 I

Re: running rich at idle

Postby virgilmobile » Wed Jun 19, 2013 3:57 pm

Hmmmm....I tend to shy away from rtv on the bike...The "O" rings still should be able to properly seal the tubes to the heads unless they were the wrong diameter in the first place..or damaged.
As I remember,the diameter was about 0.008-0.010" more than the depth of the ring they set in.
This allowed for the squish factor and proper seal.
I actually found a "O" ring in a Harbor Freight kit that worked well...A bit larger than the original but worked fine....The "kit" was less that 4 new ones from Honda.

jtimgrant
Posts: 77
Joined: Sat May 25, 2013 7:24 am
Location: Greensboro NC.
Motorcycle: 1987 GL1200 Aspencade

Re: running rich at idle

Postby jtimgrant » Wed Jun 19, 2013 5:02 pm

Thanks again Virgil. I hope to start the bike up again tonight to check for leaks.

Good to know about the harbor freight o-rings. I will check that out.

Tim




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