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What do the air jet solenoid valves do? And the air jet controller what is it's function?
 

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It is a system to control the air/fuel mix and to help properly atomize the gas and decrease fuel consumption. The solenoids open and shut the air jets to control the mix.

Kit
 

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Those are to add extra air to the carbs during deceleration to lean the mixture and prevent afterburn (backfiring). I don't know much about it because I don't own nor have I worked on a 1500 but that is my basic understanding of the system from the manual.
 

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The AJ2 and AJ3 are part of the computerized air control system. They are controlled by the Carb Control Unit. In turn, the CCU is told by the Ignition Control Unit when to open or shut the AJ2/AJ3. The ICU gets information from the Air Temp Valve (TA), the PB sensor (inside the ICU) and the Pulse Generators. Unlike a fuel injection system that meters fuel, the GL1500 air control system meters air to vary the mixture depending on air temperature, load and engine rpm.

The Air Controller is part of the high altitude compensation system. Inside it is an aneroid that expands or contracts depending on the alititude. It is inop under @ 5000 ft. Above 5k ft elevation it expands and allows more air to enter the control system thus leaning out the mixture... since higher altitudes cause a naturally richer fuel mixture.

The Shot Air System controls overly rich mixture during deacceleration. Neither of these component parts (the AJ2/AJ3 or Air Controller) are effected by the Shot Air System.

This comes from a Honda video I have about the GL1500 Carb systems.
 

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Thanks Ray.

Iguessthe problem i am havingis not related to the solenoids.I have a 88 gl1500 and iaquiredcarbs from a 1999.I had to abandon the air jet controller since the 99 carbs do not have the ports to hook it up.I rebuilt them (new jets, both sliders, accel. pump)and the only problem i have is at idle, the rpms vary about 50 to100 rpm it isn't real noticeable, like if you stand behind the bike you can't tell but if you sit on it and watch it for 30 seconds i can see and hearit. Maybe it will be okay i haven't ridden it yet. But if i hold the throttle above 1000 rpm it is smooth. i set the carbs on the bench but i need to get a vac gauge to make sure the sync is right. Couldthe sync being offcause the rpm flucuation?
 

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What do the air jet solenoid valves do? And the air jet controller what is it's function?
Good question. I have not seen a goodexplanationin any manual.

I would think it is for fuel economy. One think I notice in a 4/3 down shift or 3/4 up shift, there is a definite rpm change. Why, I do not know and my guess is the carb ecm and those air solinoids. I would have thought the function was for fuel economy (lean) and/or high engine speed for off throttle in higher gears (decel) sort of like an electric idle speed motor.

The service manual only identifies a trouble shooting section for "poor fuel economy" for the air jets. Seems that the two solenoids tee together to allow more air when both are opened.

I thought only the older GL1500 had the high altitude compensator.
 

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...I had to abandon the air jet controller since the 99 carbs do not have the ports to hook it up....
Looks like the high altitude compensator and the air jet controller is one in the same. The controller and solenoids arein the 2000 manual, and they are identified in the parts manual.

I too replaced my 88 carb with a 97. From what I remember, there was one less solenoid. I believe the solenoid removed was the decel solenoid.

 

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Yes, carbs out of sync can cause idle to fluctuate but normally it causes an 'engine knock' type noise.
You might try adjusting the slow speed adjustment screws on the front of the carbs. On the 88 model they have limiter caps on them that are removable by heating them up and pulling them straight off. Becareful if you try this because if the caps aren't hot enough and you tweeek them it can break off the tip of the slow speed adjuster. That'd be a bad thing.
On the 99 model the slow speed adjuster has a 'D' fitting for a special tool. The old one can be adjusted with a straight screwdriver... the newer one takes a special tool to fit it. Honda makes a really neat tool but it's awful pricey!! Besides, it's hard to get to with the carbs on the bike. Normally the adjusters are set on the lean side... screwing them out about 1/2 turn or so usually does the trick. But if the idle is fluctuating it can be caused by one adjuster being way off... either rich or lean. It's important that they both be equal.
 

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This comes from a Honda video I have about the GL1500 Carb systems.
Ray, did you get that video from ebay? I say two different induction system videos for the GL1500.

Was the video good?
 

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rayworx wrote:
The Shot Air System controls overly rich mixture during deacceleration. Neither of these component parts (the AJ2/AJ3 or Air Controller) are effected by the Shot Air System. This comes from a Honda video I have about the GL1500 Carb systems.
Great description Ray only one thing to add is that the Shot Air valve is there to prevent overly strong compression braking when the throttle is shut suddenly. It bypasses air around the carbs to reduce the overly high vacuum generated in the manifolds when the engine is turning fast and the throttle plates have the intake air shut off. This incidently does reduce backfiring.
 

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Ok, so the decel solenoid SA (shot air) system is separate from the carburationsystem in that it feeds into the intake manifold(s).

Does all GL1500 have a shot air system with the shot air valve?

If so, it looks like the decel solenoid SAwas removed from the newer 1500s or was it? If removed, what would control the shot air valve?

I keep thinking that there was something different I had to do when I installeda newer carb, but obviously, it would not have been the shot air system since the rest of the system would have already been in place.

Also, what energisesthe decel SA solenoid? Carb ECM? I can possibly see the input I/O for engine rpms, but what would sense high vacuum for the solenoid to open or close?
 

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I am sure it was the air jet controller that was removed from the newer 1500's. That was the only difference i found.
 

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Over the years the 1500 was 'fine tuned' to the point where the Air Shot was eliminated. I don't remember what year it was. I've never heard anything about 'excessive compression' being handled by the Air Shot Valve. They don't mention anything about it in the video.
The video came from Honda... I used to be a tech and Service Manager at a Honda dealer.
 

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Page 4-47 of my 1992 Honda service manual refers to the Shot Air Valve as being the deceleration compensation valve. If you look at the illustration on that page you can see there's a tube from the airbox through the valve to the intake throat below the throttle plate. In all earlier wings the air cutoff valve which is the device to prevent backfiring during deceleration opens more fuel flow to enrichen the mixture in the exhaust system preventing detonation. In the 1500 the valve opens which in effect leans out the mix going into the engine. That may well reduce the mixture below that at which backfiring will occur but mainly it will reduce the vacuum in the intake system making down shifting a lot easier and smoother by preventing sudden decreases of rpm upon sudden throttle closing.
 

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Don't you just hate these damn carbs! Sounds like a lot of that pollution control crap, aye?

I wonder how many of our carbs induction systems are actually operating and functioningproperly? Can't fix what we do not know.

Maybe my decel SA is non-functional. When I get off the throttle, I get a lot of engine breaking.My car that has the idle speed motor/AIR, and the car is like coasting when I get off the pedal.I guess the old carbs had them dash pots to keep the carb open for the same reason and keep the engine from dieing.

I hate to say it, but I like fuel injection.
 

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Fuel injection is more efficient for sure but even more complex when you consider the control system and all the sensors needed. The carbs on the 1500 actually are pretty good, most of these bikes run for years and hundreds of thousands of miles with no problem.
 

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Fuel injection is not any more complicated than a computer controlled carburetor and incredibly reliable. We hardly ever have a problem with the fuel injection on Honda cars other than O2 sensors, actually the old O2 sensors seldom fail, it's the new type of fuel/air ratio sensors as they call them that have been failing, usually not before 75-80,000 miles. I'm just baffled that Honda continued to put carbs on their bikes for so long after trying it on 1200s and having it on all the cars since 88.
 

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Even though fuel injection is more efficient and reliable I contend it is as complex or more so than carbs. Besides the electronics and sensors there's the higher pressure fuel pump and fuel lines. I had an '86 SEi and can vouch for the better performance due to the fuel injection system on that bike. On the other hand my 1500 runs as good as new after fifteen years and 126,000 miles on its two carburetors with no problem during all that time. My point was that the carburetion system while not the most desirable for efficiency is still a good operating system with high reliability.
 

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I'm good with that Paul, didn't mean to step on your toes and I agree, carbs are very reliable unless they are left to sit for long periods of time then they have to be cleaned in most cases. I have however fired up a lot of fuel injected cars that have sat for a long time and they just fire up and go with no problem. As far as high fuel pressure, 40 PSI really isn't much, we never replace a Honda car fuel pump (physical damage the exception) or have a leaky line.
 

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Does the 1800s have any type of OBD or fault codes.They standardizedOBD I and II for automobiles, and they have been out there for manymany years. I do not know what is on the brand new cars. Carbs have beenpretty wellantiquated.

I like or can toleratecarbs, but then you can not beat fuel injection in cold weather. I just do not like the goldwing carbs. Much of my dis-taste comes from taking the bike apart. Though one could say a carb is a carb.

When EFI first came out, I hated it. But, it became one of those issues that forces one to keep up with technology. Especially if you are going to perform any repairs. I am a little surprised that Honda did not FI all the 1500 in its time. Honda must have abandoned that technology. Some US cars had EFI beginning in the 80s.
 
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