Carb heat lines
11-02-2011, 01:17 PM
#1
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Carb heat lines
and what are they really for?
Well I did ask another member to post this up but I guess it has been left up to me.
This topic has been covered more than a few times but IMHO there are still some misconceptions about what they really do and if you should remove them or leave them in place.
Now I will say I do understand why they are questioned. In fact, if you look at the old Sports-Twin archive that Greg post on here a while back, you will see i asked that same question in early '98.
In fact I believe I was the first one to raise the question. Yeah I was a carb guy even back then.
So after looking at things I pulled them off. This was in my DynoJet and K&N days, so it also made pulling the carbs just a touch easier and i was pulling them quite often.....
Anyways, I ran it like this for around 4-5 months. Then I decided to hook them back up to see how it worked. What I found and didn't expect was that the bike immediately started running better. It took the throttle cleaner and was just smoother.
So then I spent a bit of time figuring out what was really going on.
Well first lets cover what they don't do. The most common misconception is to prevent carb icing. The last time this was mentioned the example of aircraft "carb heat" was used.
On an aircraft (yes I was a light aircraft pilot back in the days when I had some extra $$) the carb heat comes from an airbox mounted on the exhaust manifold. You select either the "fresh air" which is out side air or "carb heat" which draws from the aux airbox and yes you loose power.
The thing here though is the air is heated before it is drawn in.
Now look at the system on the bike. It is heating the carb. Now if you were doing this to prevent icing, first you would need to look at the flow rate through the carb.
We could sit here and do all the math but with my quick calulation (feel free to correct me here, it is early and I might have missed something) is that at 5K RPM with our displacement of 996cc you need to move around 10 liters per sec of air\fuel mixture through the engine.
So then you would need to do more math to figure out the flow in feet per sec through the carb. To make the point here easy to follow lets use a simple example. Lets say the intake track in 12" or 1' long (this is also having the entire length of the track heated, not just a small section)
and you have a flow rate of 10 feet per sec. (Now the flow rate on the bike will be much higher than this)
So with our example you have a 1' long heated intake and a 10 feet per sec flow rate. That gives you 1 sec to heat the air up. See how that just will not work. In order to make any change in the incoming air temp you would need to supply vast amounts of heat.
Now if they are not for icing, then how about emissions. Well the honest answer here would be yes, though there is a but to this part.
They help emissions by lowering the amount of unburnt fuel being pumped into the exhaust (which the PAIR valves then finish off in a stock set up, that is what the "popping" is) but that also increases fuel economy and power, so it might not be all that bad....
So what they are doing is heating the float bowl. This causes the fuel to atomize easier and also stay in suspension far longer.
To give you an idea on how this works here is a quick read on heating the intake and what it can do: Henry "Smokey" Yunick -- Fuel vaporizing carburetor system
While most is not really relevant to the set up on this bike, the most important part is this “On the flow bench and on the dynamometer, we’d pull out a sample of air-fuel mixture mixed by the standard carburetor, and you couldn’t punch a stopwatch fast enough before the mixture started to separate into a liquid and air again. But, when the mixture goes through the entire heated process and then through the homogenizer, it’s 20 minutes before it starts to settle out”.
So while this set up doesn't use the entier intake heating set up. Just heating the fuel will allow it to stay atomized for a longer period of time.
So how the system does work is that it flows heated coolant above the float bowls until the thermostat opens. Then it shuts off the flow.
At that point the engine should be producing enough heat to actually heat the carbs up and do the same job. Just run the bike hard for 30 -45 min and then stick your hand in there and you will see what I mean.
So in closing there are advantages and disadvantages to both set ups.
With out them, the bike will not pull as crisp or take throttle as well until the bike is completely warmed up. Though you do end up with less possible points to have a coolant leak from.
With them attached, the bike runs better but the carbs are a little tougher to pull and you might, and the key word here is might as I have never heard of one, have a coolant leak at one of the fittings.
The one other thing I can add is that if you have run without them for a while, try hooking them back up for a day..... You just might be surprised.
Also, once again there was a request for a "cut away" view of the carbs....
Well I guess i am the only one left with a good vtr cut away....
and while the carbs are not that clear, you can blow it up and clearly see that there is no water jacket around the venturi, they are solid. So that should put the whole "icing control" possibility off the table....
Damn I ramble on a lot.....
Well I did ask another member to post this up but I guess it has been left up to me.
This topic has been covered more than a few times but IMHO there are still some misconceptions about what they really do and if you should remove them or leave them in place.
Now I will say I do understand why they are questioned. In fact, if you look at the old Sports-Twin archive that Greg post on here a while back, you will see i asked that same question in early '98.
In fact I believe I was the first one to raise the question. Yeah I was a carb guy even back then.
So after looking at things I pulled them off. This was in my DynoJet and K&N days, so it also made pulling the carbs just a touch easier and i was pulling them quite often.....
Anyways, I ran it like this for around 4-5 months. Then I decided to hook them back up to see how it worked. What I found and didn't expect was that the bike immediately started running better. It took the throttle cleaner and was just smoother.
So then I spent a bit of time figuring out what was really going on.
Well first lets cover what they don't do. The most common misconception is to prevent carb icing. The last time this was mentioned the example of aircraft "carb heat" was used.
On an aircraft (yes I was a light aircraft pilot back in the days when I had some extra $$) the carb heat comes from an airbox mounted on the exhaust manifold. You select either the "fresh air" which is out side air or "carb heat" which draws from the aux airbox and yes you loose power.
The thing here though is the air is heated before it is drawn in.
Now look at the system on the bike. It is heating the carb. Now if you were doing this to prevent icing, first you would need to look at the flow rate through the carb.
We could sit here and do all the math but with my quick calulation (feel free to correct me here, it is early and I might have missed something) is that at 5K RPM with our displacement of 996cc you need to move around 10 liters per sec of air\fuel mixture through the engine.
So then you would need to do more math to figure out the flow in feet per sec through the carb. To make the point here easy to follow lets use a simple example. Lets say the intake track in 12" or 1' long (this is also having the entire length of the track heated, not just a small section)
and you have a flow rate of 10 feet per sec. (Now the flow rate on the bike will be much higher than this)
So with our example you have a 1' long heated intake and a 10 feet per sec flow rate. That gives you 1 sec to heat the air up. See how that just will not work. In order to make any change in the incoming air temp you would need to supply vast amounts of heat.
Now if they are not for icing, then how about emissions. Well the honest answer here would be yes, though there is a but to this part.
They help emissions by lowering the amount of unburnt fuel being pumped into the exhaust (which the PAIR valves then finish off in a stock set up, that is what the "popping" is) but that also increases fuel economy and power, so it might not be all that bad....
So what they are doing is heating the float bowl. This causes the fuel to atomize easier and also stay in suspension far longer.
To give you an idea on how this works here is a quick read on heating the intake and what it can do: Henry "Smokey" Yunick -- Fuel vaporizing carburetor system
While most is not really relevant to the set up on this bike, the most important part is this “On the flow bench and on the dynamometer, we’d pull out a sample of air-fuel mixture mixed by the standard carburetor, and you couldn’t punch a stopwatch fast enough before the mixture started to separate into a liquid and air again. But, when the mixture goes through the entire heated process and then through the homogenizer, it’s 20 minutes before it starts to settle out”.
So while this set up doesn't use the entier intake heating set up. Just heating the fuel will allow it to stay atomized for a longer period of time.
So how the system does work is that it flows heated coolant above the float bowls until the thermostat opens. Then it shuts off the flow.
At that point the engine should be producing enough heat to actually heat the carbs up and do the same job. Just run the bike hard for 30 -45 min and then stick your hand in there and you will see what I mean.
So in closing there are advantages and disadvantages to both set ups.
With out them, the bike will not pull as crisp or take throttle as well until the bike is completely warmed up. Though you do end up with less possible points to have a coolant leak from.
With them attached, the bike runs better but the carbs are a little tougher to pull and you might, and the key word here is might as I have never heard of one, have a coolant leak at one of the fittings.
The one other thing I can add is that if you have run without them for a while, try hooking them back up for a day..... You just might be surprised.
Also, once again there was a request for a "cut away" view of the carbs....
Well I guess i am the only one left with a good vtr cut away....
and while the carbs are not that clear, you can blow it up and clearly see that there is no water jacket around the venturi, they are solid. So that should put the whole "icing control" possibility off the table....
Damn I ramble on a lot.....
11-02-2011, 02:34 PM
#2
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Thanks. That was really informative. I have a Bonneville that has carb heaters. I'll assume they do the same thing only electrically. Thanks for the cutaway pic too. I had a VW engine with a single carb and if you didn't connect the exhaust manifold to the intake mainifold heat tube the carb would freeze on cold days.
11-02-2011, 10:13 PM
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While I agree with nearly everything you have posted, I still stand by my initial posting of it's primary purpose is to prevent carb ice. You don't need to surround the entire carb to generate the heat to melt the ice. Take for example the heat risers on an old Small Block Chevy intake manifold. They didn't even go into the carb, yet they still prevented carb ice.
Personally, I think that the fuel atomization/driveability you speak of is secondary to the intent of the coolant through the carbs. I spent my time wrenching for a living, going to school on the companies dime, etc. Everything I have ever been presented about putting heat into an intake system has been for driveability purposes in terms in induction icing, not for better atomization of fuel.
I'm not arguing that you are in fact wrong, but I do think that it's incidental to the intended purpose.
P.S. I been busy lately. Last night I was working from 11pm to about 9am this morning. I have only been out of bed for a few hours. But thanks for starting this thread.
Personally, I think that the fuel atomization/driveability you speak of is secondary to the intent of the coolant through the carbs. I spent my time wrenching for a living, going to school on the companies dime, etc. Everything I have ever been presented about putting heat into an intake system has been for driveability purposes in terms in induction icing, not for better atomization of fuel.
I'm not arguing that you are in fact wrong, but I do think that it's incidental to the intended purpose.
P.S. I been busy lately. Last night I was working from 11pm to about 9am this morning. I have only been out of bed for a few hours. But thanks for starting this thread.
11-03-2011, 08:25 AM
#4
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Liquids boil in the presence of a vacume. However in the float bowls the fuel is at 1 atmosphere and therefore the point of vaporization is raised and untill warm up the fuel is subject to a larger distance between going from pressurized liquid to a vapor in a vacume. I know that from my HVAC experiance . So that is why the bowl are heated until the engine is warm and then cut out when at a operating temprature. I put peppermint shnopps in my freezer and its cold but still flows.. drink up !
11-03-2011, 08:59 AM
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While I agree with nearly everything you have posted, I still stand by my initial posting of it's primary purpose is to prevent carb ice. You don't need to surround the entire carb to generate the heat to melt the ice. Take for example the heat risers on an old Small Block Chevy intake manifold. They didn't even go into the carb, yet they still prevented carb ice.
Personally, I think that the fuel atomization/driveability you speak of is secondary to the intent of the coolant through the carbs. I spent my time wrenching for a living, going to school on the companies dime, etc. Everything I have ever been presented about putting heat into an intake system has been for driveability purposes in terms in induction icing, not for better atomization of fuel.
I'm not arguing that you are in fact wrong, but I do think that it's incidental to the intended purpose.
P.S. I been busy lately. Last night I was working from 11pm to about 9am this morning. I have only been out of bed for a few hours. But thanks for starting this thread.
Personally, I think that the fuel atomization/driveability you speak of is secondary to the intent of the coolant through the carbs. I spent my time wrenching for a living, going to school on the companies dime, etc. Everything I have ever been presented about putting heat into an intake system has been for driveability purposes in terms in induction icing, not for better atomization of fuel.
I'm not arguing that you are in fact wrong, but I do think that it's incidental to the intended purpose.
P.S. I been busy lately. Last night I was working from 11pm to about 9am this morning. I have only been out of bed for a few hours. But thanks for starting this thread.
Because it does explain the whole concept of heating intake charges.
Also do you really thing the air being in the carb for a fraction of a second is going to pick up any heat what so ever? Also if you only heat a very small portion of the intake, what is going to keep the ice from forming ahead of behind the small heated section?
Did you look at the cut away you requested? Surround the carb to melt ice..... hell the water jacket is no where near the venturi but keep clutching at straws.... it is kind of humors....
Besides, when was the last time you heard of a bike (or even car) carb icing up? I ran bikes for years that had no carb heat lines or anything like that in all weather conditions (and yes even in what is called icing conditions) and never have had any issues or problems with carb ice.
So when you can come back with some facts, not just "I think so" then we can talk a bit more.
If not, well then you can believe it is a solution to a non existent problem all you want. Though it is rather silly....
So do what you want, believe me or not.... but carb icing....really
Also if they are for icing, then why have none of the people who have removed reported an icing problem? I didn't have one when i ran mine that way.
So once again, a solution for non existent problem or heating the fuel up for better atomization.... you choose which makes more sense....
11-03-2011, 12:27 PM
#6
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See now my question is how much radiant heat really goes up to the carbs from the warming circuit and how long until the heat from the engine heat will compensate and do the exact same thing?
And is there a point where you are over-heating the fuel? Not to the point of combustion of course, but to where as it would effect it negatively?
In smokey's example he used heated intake air in conjunction with the hot fuel, and as our intake's are designed for volume and to be cool, does this adversely effect the burning?
And is there a point where you are over-heating the fuel? Not to the point of combustion of course, but to where as it would effect it negatively?
In smokey's example he used heated intake air in conjunction with the hot fuel, and as our intake's are designed for volume and to be cool, does this adversely effect the burning?
11-03-2011, 02:04 PM
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Carb icing was a problem here in the UK on kwackas in the 80s - They recalled them to plumb in carb warmers - I remeber GPZs revving crazily on choke so as to get them to working temps ASAP. I always thought the flowing of warming coolant was to transfer heat to the carb bodies to stop ice forming from moisture in the air and adhering to the intake surface not par se to warm the air/mixture.
11-03-2011, 02:53 PM
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No need to be a condescending *****. At best, you are forming an educated guess. And yes, I read Smokey Yunicks stuff. The man was very very smart, and disporved a lot of stuff that engineers had touted as the gospel. But, the fact still remains, that at best, you are forming an educated guess based on your own experinces, and articles you have read about heating the fuel before it goes into the engine via a carb float bowl.
As for your argument about it only heating a small portion of the intake tract, thats all you need to heat. The ice will start to form at one point, and one point only, where the pressure drops in the venturi. It HAS to have a pressure drop to draw the fuel into the engine. And the rest of the carb will absorb the heat.
I'm not saying you aren't right, but you have no descernable proof other than an article written by Smokey Yunick with patents. You are guessing. I, am doing nothing different, other than the fact that I actually hold certificates of my training in the areas you are talking about. I spent 9 years as a wrench making a living at it before I had had enough of the drama and politics. How many years have you made a living wrenching?
11-03-2011, 09:01 PM
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No need to be a condescending *****. At best, you are forming an educated guess. And yes, I read Smokey Yunicks stuff. The man was very very smart, and disporved a lot of stuff that engineers had touted as the gospel. But, the fact still remains, that at best, you are forming an educated guess based on your own experinces, and articles you have read about heating the fuel before it goes into the engine via a carb float bowl.
As for your argument about it only heating a small portion of the intake tract, thats all you need to heat. The ice will start to form at one point, and one point only, where the pressure drops in the venturi. It HAS to have a pressure drop to draw the fuel into the engine. And the rest of the carb will absorb the heat.
I'm not saying you aren't right, but you have no descernable proof other than an article written by Smokey Yunick with patents. You are guessing. I, am doing nothing different, other than the fact that I actually hold certificates of my training in the areas you are talking about. I spent 9 years as a wrench making a living at it before I had had enough of the drama and politics. How many years have you made a living wrenching?
As for your argument about it only heating a small portion of the intake tract, thats all you need to heat. The ice will start to form at one point, and one point only, where the pressure drops in the venturi. It HAS to have a pressure drop to draw the fuel into the engine. And the rest of the carb will absorb the heat.
I'm not saying you aren't right, but you have no descernable proof other than an article written by Smokey Yunick with patents. You are guessing. I, am doing nothing different, other than the fact that I actually hold certificates of my training in the areas you are talking about. I spent 9 years as a wrench making a living at it before I had had enough of the drama and politics. How many years have you made a living wrenching?
So to keep this short as I really don't need the BS....
First, if you feel the millisecond that the air is actually in the venturi is enough time to warm it up enough to prevent icing...well more power to you....
Then like you have said, those Honda engineer are just smoking crack.... you see that they are trying to prevent icing but put the water jacket nowhere near the venturi..... or did you not look at the cut away you requested. I mean really wouldn't you want the heat to be somewhere close to what you want to get hot? The venturi is right where the slide is at (it's hard to miss as it is red and black in that section) and if you actually look the carb body is solid there..... guess it was good crack that day....
Then there is the issue of why do the throttle bodies on FI bikes have no heater lines. I guess FI doesn't ice.... I mean there is a venturi in there also but magically there is no problem with ice, why is that?
I guess trying to get proper atomization from a 170-180 series main jet is of no real concern..... Have any idea what size mains most bikes run?
Then you also comment on aircraft systems using carb heat to prevent icing and the drop in power that accompanies using it. So if this set up is to put heat in the bike carbs is to prevent icing, why is there no power drop when you run them?
In fact the bike runs better with them, I have done it and know what happens... have you even tried to run the bike with both set ups or are you just completely guessing?
So go enjoy your closed mind and the inability to logically work a issue out.... and I have been spinning wrenches for around 36 years now and run my own motorcycle repair business.... so try again with that one also.....
Have a nice day.
Last edited by 8541Hawk; 11-03-2011 at 09:38 PM.
11-04-2011, 11:40 AM
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Well see that is the difference between you and me. I can say your idea is down right silly without calling you names.... and we can see that you just want to personally attack someone....
So to keep this short as I really don't need the BS....
First, if you feel the millisecond that the air is actually in the venturi is enough time to warm it up enough to prevent icing...well more power to you....
Then like you have said, those Honda engineer are just smoking crack.... you see that they are trying to prevent icing but put the water jacket nowhere near the venturi..... or did you not look at the cut away you requested. I mean really wouldn't you want the heat to be somewhere close to what you want to get hot? The venturi is right where the slide is at (it's hard to miss as it is red and black in that section) and if you actually look the carb body is solid there..... guess it was good crack that day....
Then there is the issue of why do the throttle bodies on FI bikes have no heater lines. I guess FI doesn't ice.... I mean there is a venturi in there also but magically there is no problem with ice, why is that?
I guess trying to get proper atomization from a 170-180 series main jet is of no real concern..... Have any idea what size mains most bikes run?
Then you also comment on aircraft systems using carb heat to prevent icing and the drop in power that accompanies using it. So if this set up is to put heat in the bike carbs is to prevent icing, why is there no power drop when you run them?
In fact the bike runs better with them, I have done it and know what happens... have you even tried to run the bike with both set ups or are you just completely guessing?
So go enjoy your closed mind and the inability to logically work a issue out.... and I have been spinning wrenches for around 36 years now and run my own motorcycle repair business.... so try again with that one also.....
Have a nice day.
So to keep this short as I really don't need the BS....
First, if you feel the millisecond that the air is actually in the venturi is enough time to warm it up enough to prevent icing...well more power to you....
Then like you have said, those Honda engineer are just smoking crack.... you see that they are trying to prevent icing but put the water jacket nowhere near the venturi..... or did you not look at the cut away you requested. I mean really wouldn't you want the heat to be somewhere close to what you want to get hot? The venturi is right where the slide is at (it's hard to miss as it is red and black in that section) and if you actually look the carb body is solid there..... guess it was good crack that day....
Then there is the issue of why do the throttle bodies on FI bikes have no heater lines. I guess FI doesn't ice.... I mean there is a venturi in there also but magically there is no problem with ice, why is that?
I guess trying to get proper atomization from a 170-180 series main jet is of no real concern..... Have any idea what size mains most bikes run?
Then you also comment on aircraft systems using carb heat to prevent icing and the drop in power that accompanies using it. So if this set up is to put heat in the bike carbs is to prevent icing, why is there no power drop when you run them?
In fact the bike runs better with them, I have done it and know what happens... have you even tried to run the bike with both set ups or are you just completely guessing?
So go enjoy your closed mind and the inability to logically work a issue out.... and I have been spinning wrenches for around 36 years now and run my own motorcycle repair business.... so try again with that one also.....
Have a nice day.
You're real cute. This is the EXACT reason why I didn't start this thread. I don't have a desire to show everyone my superior knowledge, and belittle people with my expertise. Even still, what you are doing at best is an educated guess. I still don't see any descernable proof that this is the reason why Keihin put the heat from coolant in the carbs.
Ever seen a Toyota SR22 throttle body? It's got coolant plumbed into it. Ever seen a SBC intake manifold? It's got heat risers that are plumbed through the head to heat the intake manifold, which doesn't even heat the carb, but still prevents carb ice. And I would say about 1/2 of t-bodies on motorcycles actually have a venturi in them. The sole purpose of it is to creat a low pressure zone in the carb to draw fuel up from the float bowl. So it's not necessary in an EFI bike because the fuel is forced in under pressure.
Have a look at a 06 CBR600RR(first bike I bothered to look at). Find the coolant flow chart in the FSM. You'll see that it does infact have coolant flowing to the throttle bodies. Now, according to you, it's to heat the fuel. But there is no heat going to the fuel rail. There is heat going to the throttle bodies though. I am not sure if the have a venturi desgine, but they are heated. It doesn't take much heat to melt ice. It only has to be above freezing where the ice will form to melt it.
I am not narrow minded. I do think that there is some truth to what is happening with what you say. But, like I said, I think it's secondary to the desired results. And I think it's great that you have had a shop repairing MC's for 36 years. Kudo's to you. But I am not the one who is narrow minded here. You refuse to think that it is a secondary result. I don't. There is lots of data out there to prove it's to prevent iceing. There is only one person out there who says it's to increase performance. You are side tracking the issue by calling it something to improve performance. I am saying that it is used to prevent iceing. I did use the refrence about airplanes and the associated RPM drop, just an an example. But when you ice up a carb, you are definatly going to have an issue. Ever had to declare an emergency because you could only get 1800rpm out of a C150 because the carb had iced up so bad, and just barely made it back to the airport? I have. I spent two years instructing in them, and I sure don't want to go back.
P.S. If you didn't want this BS, then why did you start the thred?
11-04-2011, 12:21 PM
#12
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You are pretty damn funny.... and I post things to both try to help my fellow riders out and to also get people to open their minds and actually find out what is really going on, not just believe everything they are told....
So as you pretty much just blew over most of my questions, here are a couple more for you....
If the purpose of the lines is to prevent icing, why do they turn the flow off after the thermostat opens? Wouldn't that be the optimal time for carb icing?
Now I did ask about FI stuff and you missed the answer there.... the true reason they might need carb heat is that they have butterflys in them and that is where the ice forms.
So now back to the CV carb in a SH. It has no butterfly, so where is the ice supposed to form?
On the slide? Well no as it is plastic you shouldn't see any issues there.
Maybe the needle? Well yes it could but no amount of carb heat would address this and it is in the plastic slide and really has no where to get heat transfer from.
So that would only leave the throat of the carb. Now if you had ice form there, it wouldn't just stumble and die, like most icing issue you hear of.
In this case the first thing that would happen is the slide would stick. So you would have a stuck open throttle. Now I've been around SH's from '97 on and one thing I have never heard of, even with the guys that pull the lines, is a SH throttle sticking open.
The other thing I have done is actually take the bike out, with the carb heat blocked off, in optimal icing conditions. It is quite easy to do here in the bay area. Temps in the high 30's to low 40's with heavy fog.
Guess what, no issues what so ever. So with the actual testing, on this system, that I have done and by actually looking at the system, yes i have drawn conclusions. I am more than open to hearing why I could be wrong and actually look forward to the discussion. That is how one learns.
Though I also find your comment about how I'm just trying to show off how much I know funny..... yeah that is why I took the time to share what I know about setting up the carbs on this bike.
It was all just to show off, not help anyone out...... I guess I should have keep that info to myself....
Though it is people like you that make me question why I even bother.
The childish name calling when someone doesn't agree with you just makes it not worth bothering.
All I can say at this point is that I will never show off what I know to you anymore.... have a question about this bike, ask somebody else.
So as you pretty much just blew over most of my questions, here are a couple more for you....
If the purpose of the lines is to prevent icing, why do they turn the flow off after the thermostat opens? Wouldn't that be the optimal time for carb icing?
Now I did ask about FI stuff and you missed the answer there.... the true reason they might need carb heat is that they have butterflys in them and that is where the ice forms.
So now back to the CV carb in a SH. It has no butterfly, so where is the ice supposed to form?
On the slide? Well no as it is plastic you shouldn't see any issues there.
Maybe the needle? Well yes it could but no amount of carb heat would address this and it is in the plastic slide and really has no where to get heat transfer from.
So that would only leave the throat of the carb. Now if you had ice form there, it wouldn't just stumble and die, like most icing issue you hear of.
In this case the first thing that would happen is the slide would stick. So you would have a stuck open throttle. Now I've been around SH's from '97 on and one thing I have never heard of, even with the guys that pull the lines, is a SH throttle sticking open.
The other thing I have done is actually take the bike out, with the carb heat blocked off, in optimal icing conditions. It is quite easy to do here in the bay area. Temps in the high 30's to low 40's with heavy fog.
Guess what, no issues what so ever. So with the actual testing, on this system, that I have done and by actually looking at the system, yes i have drawn conclusions. I am more than open to hearing why I could be wrong and actually look forward to the discussion. That is how one learns.
Though I also find your comment about how I'm just trying to show off how much I know funny..... yeah that is why I took the time to share what I know about setting up the carbs on this bike.
It was all just to show off, not help anyone out...... I guess I should have keep that info to myself....
Though it is people like you that make me question why I even bother.
The childish name calling when someone doesn't agree with you just makes it not worth bothering.
All I can say at this point is that I will never show off what I know to you anymore.... have a question about this bike, ask somebody else.
11-04-2011, 12:54 PM
#14
Banned
MotoGP
Thread Starter
Join Date: Aug 2007
Location: Lake View Terrace, CA
Posts: 5,942
Tell you what, the lines are for icing control. I just talk out my *** and make **** up to make myself look good....
Have fun guys..... I think I need a break.
11-04-2011, 02:22 PM
#15
Senior Member
Back Marker
Join Date: Apr 2011
Posts: 201
Just felt like bolding things as to why I became so defensive. FWIW, I never said you were wrong, ever. I just think it's an added benifit of it's intended purpose. If that makes me narrow minded, then so be it.
See why I became defensive, and threw it right back in your lap? I honestly don't think my post was condescending, if you did, I'm sorry that was not my intent.
But I'd like to respond to a few things, since it also seems you have a misconception, and didn't read(or glazed over) what I wrote.
#1:The only place on a SH where you might get carb ice is in the venturi, or anywhere there might be a pressure drop, and propigate from there. Nip the source of the icing in the bud, and you likely won't have an issue. It's likely not going to happen in the ports, or where the slide is. You need to have the associated pressure drop for it to form.
#2:I have also had the experince of operating a C172 in condition conducive to icing conditions. I have never had a C172 carb ice up on me. But I have had it happen to me in a C150 in conditions that you would never guess it would happen. A lot of it has to do with how the carb is desgined. I don't think it's really an issue with the SH, but they plumbed the carbs to heat them anyways. Once the engine is warm, the heat from the engine will keep the carbs warm, just like you have already said.
#3:No worries there. I think I have this bike pretty well licked. IIRC, I remember you telling me to nix my K&N because I would never be able to get it to run right. Seems to be running quite well to me.
#4:Those two paragraphs seem contradictory.
#5:I've actually had it happen to me a few times when I had my El Camino. There wan't a whole lot stock about it. It was a SBC 383 that made 600 on the motor, and another 250 on a bottle. It didn't draw much vacuum at idle, but because it was a Single plane high rise intake manifold, the carb was always very cold, and I had it stumble on me on a regular basis if I cruised it down the fwy. It would cruise at 3500rpm at 65mph, with very little throttle input, and ice up around the butterflies, where the pressure drop was the greatest.
Again, I'm am not saying that you are wrong. I just don't think that is the sole purpose of the carbs being heated like they are. You seem to keep saying that the purpose is to heat the fuel bowls, but you keep telling me that there is no heat around the venturis. But, on the same token, there is no heat surrounding the fuel. If anything, it's all off of it splashing the point where the heated coolant runs through. This is why I say what I say.
P.S. I am all for having a valid discussion with you. But if you want to throw in smart comments, you are going to get them right back from me.
I would also like you top go to my first post in this thread and show me where I was a condescing *****. I didn't argue with you, I didn't even tell you that you were wrong. I just disagreed with it's intended purpose, at which point you tried to change my opnion to fit yours. So you see why someone would become defensive?
You are pretty damn funny.... and I post things to both try to help my fellow riders out and to also get people to open their minds and actually find out what is really going on, not just believe everything they are told....
So as you pretty much just blew over most of my questions, here are a couple more for you....
#1:If the purpose of the lines is to prevent icing, why do they turn the flow off after the thermostat opens? Wouldn't that be the optimal time for carb icing?
Now I did ask about FI stuff and you missed the answer there.... the true reason they might need carb heat is that they have butterflys in them and that is where the ice forms.
So now back to the CV carb in a SH. It has no butterfly, so where is the ice supposed to form?
On the slide? Well no as it is plastic you shouldn't see any issues there.
Maybe the needle? Well yes it could but no amount of carb heat would address this and it is in the plastic slide and really has no where to get heat transfer from.
So that would only leave the throat of the carb. Now if you had ice form there, it wouldn't just stumble and die, like most icing issue you hear of.
In this case the first thing that would happen is the slide would stick. So you would have a stuck open throttle. Now I've been around SH's from '97 on and one thing I have never heard of, even with the guys that pull the lines, is a SH throttle sticking open.
#2:The other thing I have done is actually take the bike out, with the carb heat blocked off, in optimal icing conditions. It is quite easy to do here in the bay area. Temps in the high 30's to low 40's with heavy fog.
Guess what, no issues what so ever. So with the actual testing, on this system, that I have done and by actually looking at the system, yes i have drawn conclusions. I am more than open to hearing why I could be wrong and actually look forward to the discussion. That is how one learns.
Though I also find your comment about how I'm just trying to show off how much I know funny..... yeah that is why I took the time to share what I know about setting up the carbs on this bike.
It was all just to show off, not help anyone out...... I guess I should have keep that info to myself....
Though it is people like you that make me question why I even bother.
The childish name calling when someone doesn't agree with you just makes it not worth bothering.
#3:All I can say at this point is that I will never show off what I know to you anymore.... have a question about this bike, ask somebody else.
So as you pretty much just blew over most of my questions, here are a couple more for you....
#1:If the purpose of the lines is to prevent icing, why do they turn the flow off after the thermostat opens? Wouldn't that be the optimal time for carb icing?
Now I did ask about FI stuff and you missed the answer there.... the true reason they might need carb heat is that they have butterflys in them and that is where the ice forms.
So now back to the CV carb in a SH. It has no butterfly, so where is the ice supposed to form?
On the slide? Well no as it is plastic you shouldn't see any issues there.
Maybe the needle? Well yes it could but no amount of carb heat would address this and it is in the plastic slide and really has no where to get heat transfer from.
So that would only leave the throat of the carb. Now if you had ice form there, it wouldn't just stumble and die, like most icing issue you hear of.
In this case the first thing that would happen is the slide would stick. So you would have a stuck open throttle. Now I've been around SH's from '97 on and one thing I have never heard of, even with the guys that pull the lines, is a SH throttle sticking open.
#2:The other thing I have done is actually take the bike out, with the carb heat blocked off, in optimal icing conditions. It is quite easy to do here in the bay area. Temps in the high 30's to low 40's with heavy fog.
Guess what, no issues what so ever. So with the actual testing, on this system, that I have done and by actually looking at the system, yes i have drawn conclusions. I am more than open to hearing why I could be wrong and actually look forward to the discussion. That is how one learns.
Though I also find your comment about how I'm just trying to show off how much I know funny..... yeah that is why I took the time to share what I know about setting up the carbs on this bike.
It was all just to show off, not help anyone out...... I guess I should have keep that info to myself....
Though it is people like you that make me question why I even bother.
The childish name calling when someone doesn't agree with you just makes it not worth bothering.
#3:All I can say at this point is that I will never show off what I know to you anymore.... have a question about this bike, ask somebody else.
Well you guys can be pretty funny..... first of all it appears that you didn't even bother to read this.... Henry "Smokey" Yunick -- Fuel vaporizing carburetor system
#4:Because it does explain the whole concept of heating intake charges.
Also do you really thing the air being in the carb for a fraction of a second is going to pick up any heat what so ever? Also if you only heat a very small portion of the intake, what is going to keep the ice from forming ahead of behind the small heated section?
Did you look at the cut away you requested? Surround the carb to melt ice..... hell the water jacket is no where near the venturi but keep clutching at straws.... it is kind of humors....
#5:Besides, when was the last time you heard of a bike (or even car) carb icing up? I ran bikes for years that had no carb heat lines or anything like that in all weather conditions (and yes even in what is called icing conditions) and never have had any issues or problems with carb ice.
So when you can come back with some facts, not just "I think so" then we can talk a bit more.
If not, well then you can believe it is a solution to a non existent problem all you want. Though it is rather silly....
So do what you want, believe me or not.... but carb icing....really
Also if they are for icing, then why have none of the people who have removed reported an icing problem? I didn't have one when i ran mine that way.
So once again, a solution for non existent problem or heating the fuel up for better atomization.... you choose which makes more sense....
#4:Because it does explain the whole concept of heating intake charges.
Also do you really thing the air being in the carb for a fraction of a second is going to pick up any heat what so ever? Also if you only heat a very small portion of the intake, what is going to keep the ice from forming ahead of behind the small heated section?
Did you look at the cut away you requested? Surround the carb to melt ice..... hell the water jacket is no where near the venturi but keep clutching at straws.... it is kind of humors....
#5:Besides, when was the last time you heard of a bike (or even car) carb icing up? I ran bikes for years that had no carb heat lines or anything like that in all weather conditions (and yes even in what is called icing conditions) and never have had any issues or problems with carb ice.
So when you can come back with some facts, not just "I think so" then we can talk a bit more.
If not, well then you can believe it is a solution to a non existent problem all you want. Though it is rather silly....
So do what you want, believe me or not.... but carb icing....really
Also if they are for icing, then why have none of the people who have removed reported an icing problem? I didn't have one when i ran mine that way.
So once again, a solution for non existent problem or heating the fuel up for better atomization.... you choose which makes more sense....
See why I became defensive, and threw it right back in your lap? I honestly don't think my post was condescending, if you did, I'm sorry that was not my intent.
But I'd like to respond to a few things, since it also seems you have a misconception, and didn't read(or glazed over) what I wrote.
#1:The only place on a SH where you might get carb ice is in the venturi, or anywhere there might be a pressure drop, and propigate from there. Nip the source of the icing in the bud, and you likely won't have an issue. It's likely not going to happen in the ports, or where the slide is. You need to have the associated pressure drop for it to form.
#2:I have also had the experince of operating a C172 in condition conducive to icing conditions. I have never had a C172 carb ice up on me. But I have had it happen to me in a C150 in conditions that you would never guess it would happen. A lot of it has to do with how the carb is desgined. I don't think it's really an issue with the SH, but they plumbed the carbs to heat them anyways. Once the engine is warm, the heat from the engine will keep the carbs warm, just like you have already said.
#3:No worries there. I think I have this bike pretty well licked. IIRC, I remember you telling me to nix my K&N because I would never be able to get it to run right. Seems to be running quite well to me.
#4:Those two paragraphs seem contradictory.
#5:I've actually had it happen to me a few times when I had my El Camino. There wan't a whole lot stock about it. It was a SBC 383 that made 600 on the motor, and another 250 on a bottle. It didn't draw much vacuum at idle, but because it was a Single plane high rise intake manifold, the carb was always very cold, and I had it stumble on me on a regular basis if I cruised it down the fwy. It would cruise at 3500rpm at 65mph, with very little throttle input, and ice up around the butterflies, where the pressure drop was the greatest.
Again, I'm am not saying that you are wrong. I just don't think that is the sole purpose of the carbs being heated like they are. You seem to keep saying that the purpose is to heat the fuel bowls, but you keep telling me that there is no heat around the venturis. But, on the same token, there is no heat surrounding the fuel. If anything, it's all off of it splashing the point where the heated coolant runs through. This is why I say what I say.
P.S. I am all for having a valid discussion with you. But if you want to throw in smart comments, you are going to get them right back from me.
I would also like you top go to my first post in this thread and show me where I was a condescing *****. I didn't argue with you, I didn't even tell you that you were wrong. I just disagreed with it's intended purpose, at which point you tried to change my opnion to fit yours. So you see why someone would become defensive?
11-04-2011, 02:52 PM
#17
Senior Member
Back Marker
Join Date: Apr 2011
Posts: 201
11-04-2011, 03:26 PM
#19
Senior Member
SuperSport
Join Date: Jan 2005
Location: Nooksack WA
Posts: 834
Additional info, the coolant temp sensor is wired to the ECU. This would lead me to believe that the data from the sensor is utilized in the digital ignition process to micro adjust timing to control potential detonation.
11-04-2011, 04:38 PM
#20
Out of my mind, back in 5
MotoGP
Join Date: Nov 2006
Location: Skurup, Sweden
Posts: 6,109
Actually, no you haven't got the bike running quite well... You think you have the bike running well... Your own words, best guesses... You only know the best you have experienced...
I'm saying it is infact impossible to get the bike running optimally with a K&N unless you have done quite a lot of other mods... And if you want to call that guessing, I'll gladly scan/find all the dynosheets from the three times I tried it, it'll take a while though, since I spent some hours each time until I gave in...
Put a fresh OEM filter in there, and spend a little time dialing the bike in, and I'm willing to bet you will see improvement... Or don't... Your choice...
11-04-2011, 05:12 PM
#21
Senior Member
MotoGP
Join Date: Sep 2006
Location: Austin, Tx
Posts: 4,138
Mike, maybe we should stick to airplanes. The ones that fly upside down in circles - people would think we're talented, well conditioned physically/mentally and very funny to watch. 
I hear turkeys are in season this month.
I think Wicky has it right - all our bikes were fitted only to the UK.
I hear turkeys are in season this month.
I think Wicky has it right - all our bikes were fitted only to the UK.
03-19-2012, 07:17 PM
#22
Old and dangerous
SuperSport
SuperSport
Join Date: Jan 2012
Location: DFW Texas
Posts: 604
Not that I have any knowledge on the why, I do have some personal experience with "carb icing" or whatever, on an older Ducati 900ss with reeeeally long intake manifolds/runners from the carbs down to the motor. Ran like a champ in most temperatures and weather, but when the temp got cold (almost freezing) and damp (misting), it would run for a while and then load up, like the plugs were fouling. If I stopped for a few minutes and let the heat soak for a bit. It would start right up again and run fine. Ducati made a carb heater kit for it that ran oil lines around the intake runners, just to warm the metal to keep ice from forming. It wasn't for the air or the fuel AFAIK. This only really showed up to me when I was doing a slow speed ride one year, so the engine wasn't really generating enough heat to keep the runners fully warmed. I never did get the kit, as I rarely rode my Ducati in those conditions and it never happened again. I was told it was a common occurrence in colder damp climates, and the bikes had them as standard equipment.*
As close as our carbs are to the motor, I can't see icing being much of an issue in any climate, and accept the fuel atomizing theory, but wonder then, why (I've heard) some race teams would keep their race fuel cooling on dry ice, right until filling the tank. Wouldn't that be counterproductive?
As close as our carbs are to the motor, I can't see icing being much of an issue in any climate, and accept the fuel atomizing theory, but wonder then, why (I've heard) some race teams would keep their race fuel cooling on dry ice, right until filling the tank. Wouldn't that be counterproductive?
03-19-2012, 08:46 PM
#23
Connie Demico does toad?
Superstock
Join Date: Oct 2011
Location: Lakeway
Posts: 383
While I will let the two of you have this argument all to yourself, one point of yours stand out to me...
Actually, no you haven't got the bike running quite well... You think you have the bike running well... Your own words, best guesses... You only know the best you have experienced...
I'm saying it is infact impossible to get the bike running optimally with a K&N unless you have done quite a lot of other mods... And if you want to call that guessing, I'll gladly scan/find all the dynosheets from the three times I tried it, it'll take a while though, since I spent some hours each time until I gave in...
Put a fresh OEM filter in there, and spend a little time dialing the bike in, and I'm willing to bet you will see improvement... Or don't... Your choice...
Actually, no you haven't got the bike running quite well... You think you have the bike running well... Your own words, best guesses... You only know the best you have experienced...
I'm saying it is infact impossible to get the bike running optimally with a K&N unless you have done quite a lot of other mods... And if you want to call that guessing, I'll gladly scan/find all the dynosheets from the three times I tried it, it'll take a while though, since I spent some hours each time until I gave in...
Put a fresh OEM filter in there, and spend a little time dialing the bike in, and I'm willing to bet you will see improvement... Or don't... Your choice...
I've run KN filters for decades in a miriad of machines and never even HEARD of a complaint about them. I got this bike with a KN installed and it ran damn well. Rip yer arms off well. I get on this site and most people deride the KN so I popped the 36$ for a HiFloFiltro oem replacement just to see for myself. Out of three possible outcomes it ran noticeably smoother and I will not run any other air filter in this bike. All my other KNs stay put because those machines don't have the 'feedback'? set up like this one. I think that is the part of the bike that doesn't like the way KN builds their filters. Try an OEM filter and I would be surprised if it doesn't work better. What kind of oil should I use? Tires?
04-22-2012, 07:11 PM
#24
Seasoned tech
SuperSport
Join Date: Apr 2012
Location: Issaquah, WA
Posts: 576
A couple things I see reading this thread.
Just because taking the coolant lines off and the carbs don't ice up diesn't mean Honda wasn't thinking of carb icing when they put them on. It may have been a design that is more conducive of icing so they included it in the event it is an issue but it just turned out to not be.
Also just because the coolant isn't around the throat of the carb doesn't mean it won't heat there. Aluminum is very conductive of heat so the heat from lower in the carb would very likely travel throughout the carb body very quickly and heat it all just enough to prevent any icing that could occur.
That being said the point is obviously not trying to heat the air to prevent icing , as you pointed out it's not in the carb long enough to draw any real heat. But rather just the carb body itself.
Now I'm not saying either of you are right or wrong, just pointing out a couple things I noticed in the debate.
I do have a quick question though. You said you saw an improvement when you hooked the coolant lines back up. You also said that the flow stops once the T-stat opens up. So did you only nontice the improvements when cold? Or did you notice them even after the engine was completely warm? If it was only when it was cold then I think this whole debate is mute as 99% of riding is done on a warm engine so there is no real difference one way or the other.
Just because taking the coolant lines off and the carbs don't ice up diesn't mean Honda wasn't thinking of carb icing when they put them on. It may have been a design that is more conducive of icing so they included it in the event it is an issue but it just turned out to not be.
Also just because the coolant isn't around the throat of the carb doesn't mean it won't heat there. Aluminum is very conductive of heat so the heat from lower in the carb would very likely travel throughout the carb body very quickly and heat it all just enough to prevent any icing that could occur.
That being said the point is obviously not trying to heat the air to prevent icing , as you pointed out it's not in the carb long enough to draw any real heat. But rather just the carb body itself.
Now I'm not saying either of you are right or wrong, just pointing out a couple things I noticed in the debate.
I do have a quick question though. You said you saw an improvement when you hooked the coolant lines back up. You also said that the flow stops once the T-stat opens up. So did you only nontice the improvements when cold? Or did you notice them even after the engine was completely warm? If it was only when it was cold then I think this whole debate is mute as 99% of riding is done on a warm engine so there is no real difference one way or the other.
04-23-2012, 10:07 AM
#25
Banned
MotoGP
Thread Starter
Join Date: Aug 2007
Location: Lake View Terrace, CA
Posts: 5,942
I do have a quick question though. You said you saw an improvement when you hooked the coolant lines back up. You also said that the flow stops once the T-stat opens up. So did you only nontice the improvements when cold? Or did you notice them even after the engine was completely warm? If it was only when it was cold then I think this whole debate is mute as 99% of riding is done on a warm engine so there is no real difference one way or the other.
Lets also look at this question from a different angle. When you get the bike up to temp and run it for 45mins or so, does the bike loose power? Have you ever stuck your hand in between the V of the cylinders at this point? It is bloody hot in there. Which means you have now heated the carbs.
I can answer that question and it is no. So if you don't loose any power after the engine heat soaks the carbs, why would you loose power by running coolant to them?
Which then leads to the question, if the lines don't cause you to loose any power, why remove them no matter what their true purpose is?
Last edited by 8541Hawk; 04-23-2012 at 11:10 AM.
04-23-2012, 10:53 AM
#26
Seasoned tech
SuperSport
Join Date: Apr 2012
Location: Issaquah, WA
Posts: 576
I've had a SH several years ago for a few years, and now I have another one. So I don't have a ton of time on one specifically which is why I was asking if you noticed the improvements on when cold or on a hot engine as well.
I asked a couple questions so I'm not sure which one you are saying no to. Was that no you didn't only notice the improvements when cold? Or no you didn't notice any improvements when hot?
If no improvements are noticed when hot, then the only real reason to leave it or take it out is just to simplify the system and make carb removal a little easier.
I asked a couple questions so I'm not sure which one you are saying no to. Was that no you didn't only notice the improvements when cold? Or no you didn't notice any improvements when hot?
If no improvements are noticed when hot, then the only real reason to leave it or take it out is just to simplify the system and make carb removal a little easier.
04-23-2012, 11:09 AM
#27
Banned
MotoGP
Thread Starter
Join Date: Aug 2007
Location: Lake View Terrace, CA
Posts: 5,942
You might want to re-read what I wrote as it is very clear..... I asked a simple question, Does the bike loose power when fully warmed up?
I then answered my question with, no it doesn't.
I also stated the my bike runs better anytime the thermostat is not fully open with the lines installed, which in my old riding area could be all day at times.
So once again, if the bike does not loose power when the engine heat soaks the carbs, what power increases do you think are possible by removing the lines?
Also the " it's easier to pull the carbs" line is pretty funny to me. Exactly how much time do you save by not moving to spreader clamps and poping 2 lines off?? Maybe 15 secs or so, not a big enough difference to really make it a deciding factor IMHO.
I then answered my question with, no it doesn't.
I also stated the my bike runs better anytime the thermostat is not fully open with the lines installed, which in my old riding area could be all day at times.
So once again, if the bike does not loose power when the engine heat soaks the carbs, what power increases do you think are possible by removing the lines?
Also the " it's easier to pull the carbs" line is pretty funny to me. Exactly how much time do you save by not moving to spreader clamps and poping 2 lines off?? Maybe 15 secs or so, not a big enough difference to really make it a deciding factor IMHO.
04-23-2012, 02:09 PM
#28
Seasoned tech
SuperSport
Join Date: Apr 2012
Location: Issaquah, WA
Posts: 576
Ah, OK you were answering your own question.
I agree, I wasn't using the "saves time to get carbs off" as an argument, just as the only real reason I could see in removing it if it doesn't make any difference in power by removing it.
I agree, I wasn't using the "saves time to get carbs off" as an argument, just as the only real reason I could see in removing it if it doesn't make any difference in power by removing it.
12-09-2014, 01:03 AM
#30
Senior Member
SuperBike
Join Date: Mar 2012
Location: New South Wales Australia
Posts: 1,544
Shute guys,
Riddle me this.
I run an electric water pump with no thermostat.
When I first did this mod all I wanted to do was ride it to see how it went.
Guess what, I didn't have the carb hoses hooked up and the bike felt different.
Disappointed I took the bike back into the Man Cave and hooked them up.
Then rode the bike and it felt crisp and strong.
2 years on, no thermo, hoses hooked up to carbs and the thing wails and always feels strong no matter how hot or cold.
Just my 2 bobs worth however after numerous miles under all conditions hot and cold the coolant lines stay.
Personal experience tells me they do something that is beneficial to the running and performance of this bike even though I don't understand how, and hey I don't need to understand how as I just know it runs better with them hooked up.
That is enough for me to leave them in place! And agree that the bike benefits from them being hooked up and so do I!
Cheers from Oz for now.
Riddle me this.
I run an electric water pump with no thermostat.
When I first did this mod all I wanted to do was ride it to see how it went.
Guess what, I didn't have the carb hoses hooked up and the bike felt different.
Disappointed I took the bike back into the Man Cave and hooked them up.
Then rode the bike and it felt crisp and strong.
2 years on, no thermo, hoses hooked up to carbs and the thing wails and always feels strong no matter how hot or cold.
Just my 2 bobs worth however after numerous miles under all conditions hot and cold the coolant lines stay.
Personal experience tells me they do something that is beneficial to the running and performance of this bike even though I don't understand how, and hey I don't need to understand how as I just know it runs better with them hooked up.
That is enough for me to leave them in place! And agree that the bike benefits from them being hooked up and so do I!
Cheers from Oz for now.
