81 GW 1100 runs way too rich

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Lobo

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Oct 26, 2014
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Location
Rolla , Missouri
Hi I'ma new member with a 1981 GW interstate. I have a problem ,,,,it, starts , it runs , but it's getting @26 mpg and running so rich it'll blacken the plugs in 15 min of idle. we've isolated the problem down to the idle adj screw,(maybe ) no matter where we set the idle adj screw it runs super rich, unless we take it out , then it runs super lean. It is my understanding this adjustment regulates vac, thus sucking more or less gas , backing the screw out should result in a leaner mixture. We've cleaned all ports and channels we can find . is there a channel that runs up to the main air intake body? Basically the idle adjusting screw makes no difference , all the way in or backed out 1-5 turns , unless it's all the way out and out of the bike. Any suggestions ?
LOBO
 
It sort of sounds like your describing the fuel mixture screws that sit in front of each carbs bowl, those 4 individual screws are mixture screws not air screws, by unscrewing them you are increasing the fuel and closing decreases the fuel but only at idle.
The Idle that controls all 4 carbs is at the center of the plenum up under the tank in front of the fuel filter(adjust on the right side of bike).
There are also the synchronizing screws that sit between each carb and then one on the petcock side that synchronizes left to right banks.
Anyways that said it sounds like you are way too rich to be any of those, sounds like a plenum leak, take out the air filter and look down at the plenum where it splits, do you see gas pooling inside it? It should be dry inside. Could also be the floats on all 4 carbs are stuck or mis adjusted.
Need to find where the extra fuel is coming from.
 
Hmmm...are you talking about the idle screw that adjusts all four at the same time or the mixture screw on each carb.

The screw that each carb has, also has an o-ring and little flat washer, spring loaded- so there is a spring inside too, be careful if you take apart. This can cause to much mixture if these parts are not inside also, if they are in, replace the oring, reinsert each one, screw it in lightly until it lightly bottoms out - do not force it all the way down. back it out 3 turns and leave it. then try running it if nothing else is leaking anywhere. If you do take the carbs apart, clean the jets, set the bowls, check your air-cut off valves -they may be bad - look at them with a flashlight under neath-if you see light coming thur the diaphram then you have pin holes, repalce, and leak test the carb bdfore you install it, easier to take back apart while it is off the bike. And always sync the carbs after you get it running.
 
geeze ,,,I just typed a book and it seems it got lost , I'll make this short , we've done all you have suggested. we seem to have the excess fuel isolated to the idle jets, our understanding is the mixture adjusting screw on each carb leans the mixture as you unscrew it. my buddy has an 83 GW , and that's how it works on his . It's like a soda straw with a hole in the straw above the soda.if the hole is open you get less soda , close the hole and you get more . We think there must be a channel that goes to the plenum to regulate the vacuum sucking gas out of the idle jet.Know anything about that?
Lobo
 
[url=https://classicgoldwings.com/forum/viewtopic.php?p=134601#p134601:2xft98ph said:
Lobo » Fri Oct 31, 2014 3:53 pm[/url]":2xft98ph]
geeze ,,,I just typed a book and it seems it got lost , I'll make this short , we've done all you have suggested. we seem to have the excess fuel isolated to the idle jets, our understanding is the mixture adjusting screw on each carb leans the mixture as you unscrew it. my buddy has an 83 GW , and that's how it works on his . It's like a soda straw with a hole in the straw above the soda.if the hole is open you get less soda , close the hole and you get more . We think there must be a channel that goes to the plenum to regulate the vacuum sucking gas out of the idle jet.Know anything about that?
Lobo
Click to expand...
The screw on the GL carbs is a fuel screw not an air screw, it gets the air from the butterfly being cracked open and by opening the screw it lets more fuel, closing it is less fuel...Really though the way you describe your plugs it sounds like it is getting more fuel then the idle circuit can deliver which leads me to think it is a float,oring or plenum seal leak.
 
I agree with zman, more fuel than the idle adjustment screws can deliver.
Is this happening on all 4?

FWIW, when mine was running on the stock carbs, it smelled rich at idle even though the plugs didn't show it.
 
Well I have to say Roadys carb rebuild for dummys was great, thanks a bunch for the link. But after checking and double checking we really didn't find anything we hadn't done. We are still running very rich on all cylinders. Maybe somebody put in oversized jets or damaged them in some way. One thing that has us puzzled is the accelerator pump, how does this feed all 4 carbs? And is there anyway a bad accelorator pump diagphragm could pass gas to the plenum?
 
hmmmm i cant remember ..but it seems it couldnt do that ... i think the smallest tubes that run between carbs is the fuel pump feed ...not sure though been awhile since ive done work on 1100 rack ..and i forget things instantly :hihihi:
 
Checking the accelerator passages are clear would be part of a complete going through when cleaning and adjusting. At that time is when you see how the circuit works.

Really have to make absolute certain every path is clear on all 4 of these carbs.
It's entirely possible larger jets were installed.
 
well the pic's in the book sure helped with all the passages , and we've checked and double checked them all. Now we're trying to figure out how to check the size of the jets. like I said before the bike runs and idles great , but the carbon build up because of the rich mixture will probably make that short lived. I'll keep you in the loop , eventually we'll get the problem solved. Hopefully! LOL
 
Mine always ran rich at idle too but it didn't soot the plugs.
Maybe something else is wrong like weak spark or low compression causing an incomplete burn. What's the compression and how does the spark look?
 
compression is a little high ,185-190, within 5 on all 4 cylinders . we suspect carbon to be the reason for the high readings . haven't checked ignition at all , we've got no misses or any other sign of ignition problems.
 
well if the problem is slight ..having open filter or non all should give clue if things are really bad ..but maybe it has float needle and seats that dont match up ...and is leaking gas this way constantly ...or like the slide needles are not right taper ... seems to be in this territory to get it through out rpm zone ....i am just throwing things out there to look at...many claim after market rebuild parts form some dont work good ..maybe these carbs were redone with bad parts at one time ....
 

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