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Discussion Starter · #1 ·
From the last discussion, I have read good feeds and made and checked the carbs myself. I have noticed that the fuel line wasn’t cleaned AT ALL. So I cleaned it myself. Now I can go to 9k Rpm without delays. But at traffic I noticed that the rpm rises on it’s own. I searched and saw on youtube that it’s an idle screw issue, MAYBE. My screws are adjusted at 2 turns. How much turns should I do? Am I to lean or rich? My jets are 108 and jet screw are 38.
 

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There is a single black knob that adjust the idle for all 4 carbs. It functions by moving the linkage that the throttle cable connects to. Try adjusting that first.

Each carb does have an idle air screw. Those are the ones underneath.

#38 pilots are larger than stock you you should start with 1 turn out on the idle air screws. Adjust them at equal 1/4 or 1/2 turns until they are running decent.

The smaller stock jets like about 2 1/3 turns so I doubt you'd need that much with the 38's/
 

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Discussion Starter · #3 ·
There is a single black knob that adjust the idle for all 4 carbs. It functions by moving the linkage that the throttle cable connects to. Try adjusting that first.

Each carb does have an idle air screw. Those are the ones underneath.

#38 pilots are larger than stock you you should start with 1 turn out on the idle air screws. Adjust them at equal 1/4 or 1/2 turns until they are running decent.

The smaller stock jets like about 2 1/3 turns so I doubt you'd need that much with the 38's/
Do you have a photo of this black knob? I’m quite confused with the carb. Or are you referring with the screw? The one with the small spring?
 

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This is the idle knob. On the same side of the bike as the petcock & clutch. There's only one. It adjusts the idle for all 4 carbs at the same time. If your bike is idling too high or low this is what you want to adjust it with.

123114


These are the pilot air screws. There is one per carb. Adjusting these will change how the bike starts and runs at certain speeds.

123115
 

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Discussion Starter · #5 ·
This is the idle knob. On the same side of the bike as the petcock & clutch. There's only one. It adjusts the idle for all 4 carbs at the same time. If your bike is idling too high or low this is what you want to adjust it with.

View attachment 123114

These are the pilot air screws. There is one per carb. Adjusting these will change how the bike starts and runs at certain speeds.

View attachment 123115
Thank you so much! I
This is the idle knob. On the same side of the bike as the petcock & clutch. There's only one. It adjusts the idle for all 4 carbs at the same time. If your bike is idling too high or low this is what you want to adjust it with.

View attachment 123114

These are the pilot air screws. There is one per carb. Adjusting these will change how the bike starts and runs at certain speeds.

View attachment 123115
[/QUOTE
This is the idle knob. On the same side of the bike as the petcock & clutch. There's only one. It adjusts the idle for all 4 carbs at the same time. If your bike is idling too high or low this is what you want to adjust it with.

View attachment 123114

These are the pilot air screws. There is one per carb. Adjusting these will change how the bike starts and runs at certain speeds.

View attachment 123115
thank you so much! I’ve been adjusting this knob. When I idle at traffic the rpm goes wild or low but when I’m driving, it’s not. Thanks for the photo and advice sir!
 

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Discussion Starter · #6 ·
This is the idle knob. On the same side of the bike as the petcock & clutch. There's only one. It adjusts the idle for all 4 carbs at the same time. If your bike is idling too high or low this is what you want to adjust it with.

View attachment 123114

These are the pilot air screws. There is one per carb. Adjusting these will change how the bike starts and runs at certain speeds.

View attachment 123115
I was cleaning my tank and I saw this. Do you know what’s this? It’s like a tube at the bottom of the tank
 

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It is the tank over fill drain, and it should have rubber hose to the ground.

The screw Obo called 'air screws' are actually pilot mix screws (fuel not air). Don't know if you are spelling the problem correctly, but if you have a 'rising' idle on its own, you may have a vacuum leak problem, otherwise all adjustment spoken here produce fixed settings.
 

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Discussion Starter · #8 ·
It is the tank over fill drain, and it should have rubber hose to the ground.

The screw Obo called 'air screws' are actually pilot mix screws (fuel not air). Don't know if you are spelling the problem correctly, but if you have a 'rising' idle on its own, you may have a vacuum leak problem, otherwise all adjustment spoken here produce fixed settings.
What do you mean on vacuum leak problem? I’m quite new to maintaining this bike so I have no idea what that term means. Where does the vacuum leak problem occur?
 

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Your statement was 'idle rises on its own'. Usually means engine is getting extra air not metered by the carburetors. These bikes have a vacuum system to the petcock, and the Kawasaki Kleen air valve to the exhaust valve, if this bike came equipped with one. A leak here, means engine getting extra air and would increase idle

........did you really mean to say idle is rising on its own, or just the idle is high always?
 

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The screw Obo called 'air screws' are actually pilot mix screws (fuel not air).
Pilot screws are also called pilot air screws, and air screws. They control the amount of air which enters the carb fuel circuit. Turn in reduces the amount of air (richens the mixture), turn out increases the amount of air (leans the mixture).
 
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I'll confirm I've had issues where my idle automatically went up when I came to a stop light. No idea why. Using the black idle knob I simply reached down and lowered it.

Here's the naming I go by...

123118


and what Kawi calls the parts I bought ((Screw, - pilot air) at least here in Canada) :)
123119


As for the hose there are 2 hoses that attach to the underside of the tank. One is the overflow/drain hose and the other is a vent hose. The overflow/drain hose allows any water or excess fuel that gets around the filler neck to drain away from the hot engine. (fuel on a hot engine can ignite) Here's where the drain hole is on the upper side (see inserted allen key as a probe). They sometimes get plugged with dirt and stuff. The locking fuel cover is removed in this photo.

123120



The vent line allows air to get into the tank as the fuel drains out. If it wasn't there the bike wouldn't get fuel and run. It ha a hose in case any fuel came out it as well to keep it away from the engine.

As for a vacuum leak there are a few of the hoses that are attached to the carb that have are negatively pressurized (a vacuum) as the bike sucks the air/fuel mixture into the engine. That vacuum is required to make a few things work properly. The petcock requires a vacuum to let the fuel run and so does the PAIR valve (unless it was removed on your bike) as well as possible some emissions stuff if you have a California model.

For hoses to the carbs there should be 2 (one to the petcock & one to the pair valve) There should also be two block off nipples. They should attach to a carb (1 hose or nipple per carb). If any of these are damaged and leaking you have a vacuum leak and may experience running issues.

The other place you could have a leak is the boots that connect the carbs to the engine. It's not uncommon for them to be cracked give the age, but they have a metal liner so they may look bad but still be ok. Alternatively they might be bad and leaking. This will mess up the air/fuel mix going to the engine and cause running issues too.

 

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Did you synchronize the carbs? (This will only effect smooth idle and off idle response.)
Are the slide diagrams properly seated?

One thing to note when it comes to carbs.. all it takes is one part of the system to be off and the bike will operate miserably. Or it could be something virtually undetectable such as somebody ham-fisted the pilot screws (those small external screws underneath, one per carb) and turned them too tightly closed to seat them when counting turns out. What happens now is they have damaged the pilot seat and permanently changed the size of the hole in the carb body and it may never idle correctly.

And there are several circuits inside the carbs, each comes into play depending on throttle position with overlap when transitioning from one circuit to another. As others have stated, all vacuum lines and caps must be 100% sound as well as seals and carb holders.

Carburetors can be a mystery but they can be learned. You must be careful with them and don't try to out-think the engineers that designed them. Take them apart to clean them but only put them back together as they came apart, no monkeying around.

As Obo mentioned, the 2,3 carbs have different jetting than the 1,4 carbs. If mixed up I have no idea how the engine will perform, and I never want to find out. Did your mechanic know this?
 

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Discussion Starter · #15 ·
Your statement was 'idle rises on its own'. Usually means engine is getting extra air not metered by the carburetors. These bikes have a vacuum system to the petcock, and the Kawasaki Kleen air valve to the exhaust valve, if this bike came equipped with one. A leak here, means engine getting extra air and would increase idle

........did you really mean to say idle is rising on its own, or just the idle is high always?
What is the Kleen air valve? Does the kawasaki zr7 has one? I’ll check the carb tomorrow and send a pic here. Maybe the mechanic made some errors.
Yes. The idle is rising on its own. My idle is at 1k but after a 30 minute drive, and I stop due to traffic the idle rises on it’s own.
 

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Discussion Starter · #16 ·
I'll confirm I've had issues where my idle automatically went up when I came to a stop light. No idea why. Using the black idle knob I simply reached down and lowered it.

Here's the naming I go by...

View attachment 123118

and what Kawi calls the parts I bought ((Screw, - pilot air) at least here in Canada) :)
View attachment 123119

As for the hose there are 2 hoses that attach to the underside of the tank. One is the overflow/drain hose and the other is a vent hose. The overflow/drain hose allows any water or excess fuel that gets around the filler neck to drain away from the hot engine. (fuel on a hot engine can ignite) Here's where the drain hole is on the upper side (see inserted allen key as a probe). They sometimes get plugged with dirt and stuff. The locking fuel cover is removed in this photo.

View attachment 123120


The vent line allows air to get into the tank as the fuel drains out. If it wasn't there the bike wouldn't get fuel and run. It ha a hose in case any fuel came out it as well to keep it away from the engine.

As for a vacuum leak there are a few of the hoses that are attached to the carb that have are negatively pressurized (a vacuum) as the bike sucks the air/fuel mixture into the engine. That vacuum is required to make a few things work properly. The petcock requires a vacuum to let the fuel run and so does the PAIR valve (unless it was removed on your bike) as well as possible some emissions stuff if you have a California model.

For hoses to the carbs there should be 2 (one to the petcock & one to the pair valve) There should also be two block off nipples. They should attach to a carb (1 hose or nipple per carb). If any of these are damaged and leaking you have a vacuum leak and may experience running issues.

The other place you could have a leak is the boots that connect the carbs to the engine. It's not uncommon for them to be cracked give the age, but they have a metal liner so they may look bad but still be ok. Alternatively they might be bad and leaking. This will mess up the air/fuel mix going to the engine and cause running issues too.

I’ve actually changed boots a year ago.
I'll confirm I've had issues where my idle automatically went up when I came to a stop light. No idea why. Using the black idle knob I simply reached down and lowered it.

Here's the naming I go by...

View attachment 123118

and what Kawi calls the parts I bought ((Screw, - pilot air) at least here in Canada) :)
View attachment 123119

As for the hose there are 2 hoses that attach to the underside of the tank. One is the overflow/drain hose and the other is a vent hose. The overflow/drain hose allows any water or excess fuel that gets around the filler neck to drain away from the hot engine. (fuel on a hot engine can ignite) Here's where the drain hole is on the upper side (see inserted allen key as a probe). They sometimes get plugged with dirt and stuff. The locking fuel cover is removed in this photo.

View attachment 123120


The vent line allows air to get into the tank as the fuel drains out. If it wasn't there the bike wouldn't get fuel and run. It ha a hose in case any fuel came out it as well to keep it away from the engine.

As for a vacuum leak there are a few of the hoses that are attached to the carb that have are negatively pressurized (a vacuum) as the bike sucks the air/fuel mixture into the engine. That vacuum is required to make a few things work properly. The petcock requires a vacuum to let the fuel run and so does the PAIR valve (unless it was removed on your bike) as well as possible some emissions stuff if you have a California model.

For hoses to the carbs there should be 2 (one to the petcock & one to the pair valve) There should also be two block off nipples. They should attach to a carb (1 hose or nipple per carb). If any of these are damaged and leaking you have a vacuum leak and may experience running issues.

The other place you could have a leak is the boots that connect the carbs to the engine. It's not uncommon for them to be cracked give the age, but they have a metal liner so they may look bad but still be ok. Alternatively they might be bad and leaking. This will mess up the air/fuel mix going to the engine and cause running issues too.

I’ll try this method on the boots. Maybe I’ve got a leak on the boots since at low rpm, I sometimes hear an hissing sound which makes me harder to find power on the bike. I’ll send a photo on my carb tomorrow morning. I hope you’ll can help me with this. Maybe the mechanic got some errors. I’ll be cleaning my the tank drank with compressed air and carb cleaner. Is the pair valve the same with the petcock vacuum? Thank you so much Obo! You’ve been a great help! I’m sorry for taking much of your time!
 

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Discussion Starter · #17 · (Edited)
Did you synchronize the carbs? (This will only effect smooth idle and off idle response.)
Are the slide diagrams properly seated?

One thing to note when it comes to carbs.. all it takes is one part of the system to be off and the bike will operate miserably. Or it could be something virtually undetectable such as somebody ham-fisted the pilot screws (those small external screws underneath, one per carb) and turned them too tightly closed to seat them when counting turns out. What happens now is they have damaged the pilot seat and permanently changed the size of the hole in the carb body and it may never idle correctly.

And there are several circuits inside the carbs, each comes into play depending on throttle position with overlap when transitioning from one circuit to another. As others have stated, all vacuum lines and caps must be 100% sound as well as seals and carb holders.

Carburetors can be a mystery but they can be learned. You must be careful with them and don't try to out-think the engineers that designed them. Take them apart to clean them but only put them back together as they came apart, no monkeying around.

As Obo mentioned, the 2,3 carbs have different jetting than the 1,4 carbs. If mixed up I have no idea how the engine will perform, and I never want to find out. Did your mechanic know this?
I did synchronized the carbs. I guess the mechanic did not know this. I’ve seen him interchanged the bottom cover and I was the one to put it back. How do I know which carb is number 1? Do I count the carb from left to right? i know the slide diaphragm are seated right. BUT HE DID PUT SOME spacer on the needle, he says it will correct the fuel consumption of my bike. Am I going to remove that spacer?
 

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I did synchronized the carbs. I guess the mechanic did not know this. I’ve seen him interchanged the bottom cover and I was the one to put it back. How do I know which carb is number 1? Do I count the carb from left to right? i know the slide diaphragm are seated right. BUT HE DID PUT SOME spacer on the needle, he says it will correct the fuel consumption of my bike. Am I going to remove that spacer?
#1 carb is on the left as you sit on the bike.
Adding a spacer under the jet needle lifts it out of the needle jet which lets more fuel into the airstream... more fuel consumption.
If it were my problem, I'd get the carbs back to stock until the engine ran perfectly.
When you say the idle 'rises on its own', do you mean constantly or just at some point during the ride?
I notice my idle RPM changes slightly during different times of the day, most likely owing to engine heat. But only by 100-200 RPM.
Can you post a video of your problem?
 

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Discussion Starter · #19 ·
#1 carb is on the left as you sit on the bike.
Adding a spacer under the jet needle lifts it out of the needle jet which lets more fuel into the airstream... more fuel consumption.
If it were my problem, I'd get the carbs back to stock until the engine ran perfectly.
When you say the idle 'rises on its own', do you mean constantly or just at some point during the ride?
I notice my idle RPM changes slightly during different times of the day, most likely owing to engine heat. But only by 100-200 RPM.
Can you post a video of your problem?
That’s what he said. But the reason why my carb was gasping for fuel is because I have a clogged fuel line but that’s already fixed. Yet, he says it’s okay to have the needle have spacer. At some point during the ride sir, when I feel the engines to hot but the idle rises from 1k rpm to 2-3k rpm. At slow speed, when there’s a road bump, I hear my exhaust popping and my carbs hissing. I’ll have a ride this afternoon and I’ll post a vid about the idle.
 

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Discussion Starter · #20 ·
#1 carb is on the left as you sit on the bike.
Adding a spacer under the jet needle lifts it out of the needle jet which lets more fuel into the airstream... more fuel consumption.
If it were my problem, I'd get the carbs back to stock until the engine ran perfectly.
When you say the idle 'rises on its own', do you mean constantly or just at some point during the ride?
I notice my idle RPM changes slightly during different times of the day, most likely owing to engine heat. But only by 100-200 RPM.
Can you post a video of your problem?
#1 carb is on the left as you sit on the bike.
Adding a spacer under the jet needle lifts it out of the needle jet which lets more fuel into the airstream... more fuel consumption.
If it were my problem, I'd get the carbs back to stock until the engine ran perfectly.
When you say the idle 'rises on its own', do you mean constantly or just at some point during the ride?
I notice my idle RPM changes slightly during different times of the day, most likely owing to engine heat. But only by 100-200 RPM.
Can you post a video of your problem?
Here’s the hissing sound on my bike.


And here’s the vid of the bike at 2k rpm
I’m used at 1k rpm but sometimes it’s higher than 2k rpm. I was pressing clutch that time.
 
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