Carb problem gl1100.


Information and questions on GL1100 Goldwings (1980-1983)
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Cosmobiker
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Carb problem gl1100.

Post by Cosmobiker »



The bike ran fine and suddenly it started to backfire on low rpm. Took off carbs and found nothing wrong. I changed the needles in the float valves as i had it open. I have notised that there are fuel in the oil in the engine. Changed the fuel pump and belived it was solved. But no. So I read that it could be the needles. I have set the float height correctly. 15.5mm. The engine is idling but not quite as nice as I would like. When i pull the plugcap on nr.4 no reaction. I started to sync the carbs. But not getting the smooth sound i want. Ok. Gave up. Took the sync tool off. When i take off the adapters to plug the holes the rpm drops. When i took it off nr. 4 it reved up. So i think it is not getting air? What can cause this? Is the slider stuck open? Or can there be obstruction to the air mixture screw?


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virgilmobile
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Re: Carb problem gl1100.

Post by virgilmobile »

By your description #4 carb is dumping too much fuel into the cylinder.it won't be because of a stuck slide or "air mix screw".That just meters the slow speed jet...unless it's screwed many turns out.
Either way 'off they come again'.
Possible problems..
Throttle valve position not equal.
Needle valve (float) not sealing or float not properly set.
Missing slow speed jet.

I do suggest a couple of things including the normal service.
Always bench test the carbs before you put them back on the bike.

I polish the needle valve seats with a "Q" tip and brasso unless there replaced with the needle valves.
Do just let the floats rest on the needle when I measured the float height.I lean the carb pack back till the float swings..never compressing the little spring plunger.Tilt the carb pack slowly several times to be certain that the floats don't stick.
Never lay the carb pack flat down to check the float height and they must be the same height front/back/side to side.

I do gravity fill the carbs with fuel from 4 foot raised container...let it set for a few minutes then disconnect the fuel..Drain each carb bowl and (as close as you can) get a idea how much fuel is there.
Compare each carb bowl fuel amount.They need to be the same.
Mechanically adjust each throttle plate so they open and close (as close to) exactly the same time and amount.
If you have a shop vacuum,attach it to each carb runner in turn and watch the slide move up and down with the throttle.Check that each one moves the same.
Preset each slow speed mixture screw by the book as a starting point.

Sorry this is a long read but each step is needed.
Carbs should be...Service.. Bench check.. install..sync and done.
Cosmobiker
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Motorcycle: 1980 gl1100

Re: Carb problem gl1100.

Post by Cosmobiker »

I have put in keihin aftermarket idle jets. And airmix screw set 1.5 out on all four. I suspect the spring plunger on the needles are too soft on the originals. I have unoriginal from a spare carb set and put those on. I set the rack upright so the flaots lean onto the plunger and measure. I will loosen rhe inntake and look into the carb to see if nr. 4 slide is stuck in an open position. I changed the airmix screw also. Can the o ring have shifted and clogged the hole?
Cosmobiker
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Re: Carb problem gl1100.

Post by Cosmobiker »

I use this idle jet. Somebody had used a thick wire and widened the originals.
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virgilmobile
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Re: Carb problem gl1100.

Post by virgilmobile »

Cosmobiker wrote: Thu May 23, 2019 12:06 pm I use this idle jet. Somebody had used a thick wire and widened the originals.
That's the main jet.It doesn't come into play at a idle.Theres not enough airflow to suck fuel up out of it unless the throttle plate is open further than the other 3.
If the "O" ring is out of position it may clog the slow speed opening and cut the idle fuel off.Not your problem but do check anyways.
Before you knock it apart..when you get the carbs out...drain each carb bowl and look at the amount of each.. closely...If one has obviously more fuel than the others you need only to tend to that carb.Pay attention to the throttle plates too.see that they all are set the same.
Get anal about the float measurement..Front to back..side to side..and the pivot pin must not bind.The needle sides should be polished and the seat cleaned.
Cosmobiker
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Re: Carb problem gl1100.

Post by Cosmobiker »

That is the pressed in jet. Isnt that the idle jet. I tought that thr main jet is the one under the needle jet under the slide.
Cosmobiker
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Re: Carb problem gl1100.

Post by Cosmobiker »

Main jet on top and idle on the bottom? Is it possible to press these too far in?
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virgilmobile
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Re: Carb problem gl1100.

Post by virgilmobile »

You are correct.Main top,slow jet bottom.
Should not have a fitment issue.As long as the slow jet is firmly seated.
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virgilmobile
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83 GL1100 I
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Re: Carb problem gl1100.

Post by virgilmobile »

Keep in mind..all this is based on the premise that that cylinder starter firing when you pulled the hose off and introduced more air to that cylinder.
Cosmobiker
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Re: Carb problem gl1100.

Post by Cosmobiker »

Yes. The plug was wet. So there are either too much fuel or no air in the mix.
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virgilmobile
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Re: Carb problem gl1100.

Post by virgilmobile »

It sounds like your on the right track.Keep us posted.
Cosmobiker
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Re: Carb problem gl1100.

Post by Cosmobiker »

The plenum is wet between 3 and 4. It is pulsating fuel from nr 4. after I took off the flanges. It looks like it is dripping from the throttle plate? Can it accumulate fuel in the upper part of the carb? Can there bee a problem with the diaphragm on the side? Tried to get it on tape but only got picture.
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OldguyGlen
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1966 Honda 90

Re: Carb problem gl1100.

Post by OldguyGlen »

If you conclude that #4 is flooding, try to confirm if its flooding even with the engine off (assuming petcock = on and fuel tank is full enough to gravity feed fuel thru the pump). If fuel is flooding under that condition it is probably due to high float bowl level. It would rise up thru both the high jet and the low jets. It would run toward the outboard side and appear to be leaking around the closed butterfly. If all this is true you have a float needle leak, at its tip, or the gasket behind the seat.

Just a side comment.... that carb pic shows a very clean and shiny throat. Mine are way more dull looking. How did you get it that clean?
Cosmobiker
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Re: Carb problem gl1100.

Post by Cosmobiker »

I have used a ultrasonic cleaner with hot soap water. But the bend on the intake is also very clean on nr. 4. I have ordered new needle valves from Randakk. The originals are too soft i think and overfeeds the carbs. I now tried some unoriginals. They were slightly longer plungers on and im not comfy using those. I will try to check if it is leaking after engine shut of. But yesterday it looked like it was dripping from the butterfly. Like it was comming from one of the sides. The bike has always had bery smelly echaust. I have tried to gibe it ekstra air on the mix screw, 2 whole turns and i think that helps. So last weekend running fine, all of a sudden backfire and coughing.
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OldguyGlen
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Re: Carb problem gl1100.

Post by OldguyGlen »

Just to clarify the idle screw function. These are fuel screws, not air screws. CCW = more fuel, not more air.
Cosmobiker
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Re: Carb problem gl1100.

Post by Cosmobiker »

So if i turn it in it will get leaner?
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OldguyGlen
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Re: Carb problem gl1100.

Post by OldguyGlen »

Yes... Adjust it for max idle speed. But, to be sure it has a proper effect the idle and low jet passages must be clear, and overall idle setting below 1000 rpm. If it is already idling too fast the idle screw no longer has much influence. Also if that carb is flooding due to float needle problems, the screw won't do much.
Cosmobiker
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Re: Carb problem gl1100.

Post by Cosmobiker »

I put the rack on the bench. Connected fueltank 4 feet up. No leaking. But it started to pulse below the butterfly on nr 1 and 4. Drained the fuel. All equal but nr. 4. This some more fuel in it. Then I suddenly saw that one of the screws on the top cover was halfway out! That will affect the vaccum i guess. Then i flipped it over and started with 2 and 4. I polished the needle seat with qtip and autosol. Then i made a cardboard template for setting the float height. I will not stop untill they are spot on. I noticed that the rod on my accelpump does not have any free play and is slightly engaged all the time.
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Cosmobiker
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Re: Carb problem gl1100.

Post by Cosmobiker »

I put it together. Placed it on the floor by the bike and connected it to the filter. Opened the fueltap. Many minutes.. I pump the throttle. Fuel in every carb. Still nothing. I opened the filler cap and i see that it starts to bubble in a see thru filter i used to connect to the main fuel line and then nr. 2 and 4 start to flood. Do they get too much pressure?
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OldguyGlen
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Re: Carb problem gl1100.

Post by OldguyGlen »

I know you have checked many times... but it seems the float valves are still not shutting the fuel off. They should handle 4 foot of "head pressure" from the supply tank. While they are on the floor, take the round covers off and lift the pistons out. If you see fuel coming up the main jets, you can be certain the bowls are flooding. Are there gaskets on those needle valve seats? Are the floats on upside down?
Cosmobiker
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Re: Carb problem gl1100.

Post by Cosmobiker »

I have needles from Randakk on the way in the mail. The originals are too weak springs. This is some aftermarket from a parts carb rack i bought. On the bright side I get pretty good at tweaking the floats. :lol:
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OldguyGlen
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Re: Carb problem gl1100.

Post by OldguyGlen »

Just for "education purposes", bend those float tangs to provide more shut-off force on the needles. If it stops the flooding, then you know the new needles will solve the problem when they arrive. I replaced 2 of mine when I could not free the little plungers. The replacements were aftermarket and seemed just a tad longer. But I adjusted the floats to match and they seem to work fine.


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