Carburettor heater hoses to prevent carb icing - are they needed?

[wirral_biker]

][url=https://flic.kr/p/2iftiq6]IMG_1911 by KC, on Flickr[/url]

Not sure if the photo will be shown on here...but took the carbs off today on my May 1997 UK spec F6C, just for a clean and found that they have hot water from radiator running past them ( through those black hoses but they don't actually connect through the carbs themselves, just simply run underneath as a sort of carb icing heater.          These are summer bikes in the UK so was wondering if those hoses could be removed?

[John Schmidt]

No radiator heating involved. The long black hoses are simply vents that plug into the two hole brace. The short tubes between the carbs are for fuel. Only other tubes are for draining the carbs.

[The emperor has no clothes]

No radiator heating involved. The long black hoses are simply vents that plug into the two hole brace. The short tubes between the carbs are for fuel. Only other tubes are for draining the carbs.

John, I think his are different. Mine don’t have those. I think I remember Leathel talking about that on his New Zealand model. Along with a different idle screw setup. Also, I think those models have a much smaller main jet.
 I would suspect they are not so much for deicing, but for emission control.

[wirral_biker]

Well they connect to the radiator and were full of anti freeze 

I don't think they are emission, just warmth for the carbs etc.

It is true about the mixture screws on mine as being 1 3/4 turns out ( just for the 1997 year ONLY ).

I'll be starting her up tomorrow ( have to first submit to a dentist in the morning ) just to check for leaks etc.

[Leathel]

I removed mine, had them on my UK sold Valk (imported to NZ from the previous owner)  not controlled from memory so heating year round and warm fuel = loss of power

[Leathel]

Well they connect to the radiator and were full of anti freeze 

I don't think they are emission, just warmth for the carbs etc.

It is true about the mixture screws on mine as being 1 3/4 turns out ( just for the 1997 year ONLY ).

I'll be starting her up tomorrow ( have to first submit to a dentist in the morning ) just to check for leaks etc.

was yours the UK model? Smaller pigs tails, Extra foam in the air cleaner, 78 main jets, TPS on the back of the RH side

[98valk]

I removed mine, had them on my UK sold Valk (imported to NZ from the previous owner)  not controlled from memory so heating year round and warm fuel = loss of power

actually, if set up right, heated could be more power not less.  heated fuel will vaporize quicker and better.

[John Schmidt]

Well there ya go, I learned something about the UK bikes. Can't imagine why it's needed but so be it! 

[Ken aka Oil Burner]

Don't know why either. I've ridden in temps well below freezing a few times; even on the highway. Never had any freezing issues. I know it's possible, but why on UK spec bikes and not USA spec bikes? It gets cold here too.

[steveB (VRCC UK)]

Well it's not cold and salty here in my part of the UK its very wet and mild (12C). Anyhow took a stroll to my workshop to check my own Valks as I seem to have worked on Valks with and without carb heaters. My 98 does not have carb heaters so no cut out in the left side radiator cover. My 2000 has carb heaters with a cut out in rad cover to the extra outlet in the rad. Both bikes are Euro spec sold new in the UK.
Strangely both have the same jetting and pre-filter air boxes and both ride exactly the same. I see no problem in removing the heaters and blocking the outlets but why?
Check your VIN no on Dags Valk geneology site www.valkyrienorway.com/Valkyrie%20Genealogy.html and it's probable that yours is a Scandinavian model. My 2002 (fast black) was supplied through the Belgium distibutor to my local dealer and the VIN plate indicates it was specced for Sweden (a very much colder clime). I've never noticed any difference between early and later models even in freezing weather.
My own feeling - as the Euro models have smaller pilot and main jets than the USA models the heaters are there to aid enrichment (warming up) not carb icing as such. (I thought it was usual to warm manifolds to prevent icing).

[wirral_biker]

Well they connect to the radiator and were full of anti freeze  

I don't think they are emission, just warmth for the carbs etc.

It is true about the mixture screws on mine as being 1 3/4 turns out ( just for the 1997 year ONLY ).

I'll be starting her up tomorrow ( have to first submit to a dentist in the morning ) just to check for leaks etc. as the piping covers one of the float bowl screws on each carb!!

was yours the UK model? Smaller pigs tails, Extra foam in the air cleaner, 78 main jets, TPS on the back of the RH side

Yes, exactly as described, one of the first UK models.   I couldn't get the small ( hex ) bolts out to release the water pipes and get the float bowls off!

[WintrSol]

If you really want to know why you heat the carbs, the answer lies in what my FIL explained to me; he was a long-time engineer at the Carter Carburetor company. It seems that when the fuel is atomized into a fine mist, there is a large temperature drop, especially as the velocity in the venturi approaches the speed of sound. This high velocity works for you, in that the fuel is broken into ever finer droplets, which create the best combustion. The temperature drop works against you, as the colder the mist, the more it wants to condense into rain, which is bad for combustion. So, if you heat the fuel a bit, or keep the venturi warm, condensation is less likely to occur. In autos, the manifold was often heated, to keep the mist from forming 'dew', and just dripping into the cylinders, but we don't have a manifold. Thing is, if you heat it too much, the fine droplets in the mist turn into vapor, which also doesn't burn as well in an engine, so you have to balance the amount of heat against the temperature drop; in colder climates, this works well, but nearer the equator, not so much.

[Leathel]

Well they connect to the radiator and were full of anti freeze  

I don't think they are emission, just warmth for the carbs etc.

It is true about the mixture screws on mine as being 1 3/4 turns out ( just for the 1997 year ONLY ).

I'll be starting her up tomorrow ( have to first submit to a dentist in the morning ) just to check for leaks etc. as the piping covers one of the float bowl screws on each carb!!

was yours the UK model? Smaller pigs tails, Extra foam in the air cleaner, 78 main jets, TPS on the back of the RH side

Yes, exactly as described, one of the first UK models.   I couldn't get the small ( hex ) bolts out to release the water pipes and get the float bowls off!

The hex screws have countersunk heads and are quite long, plenty of room to drill the heads off and use vice grips to remove the shaft of the screw when the pipe is off,  you don't need the screws after its removed the thread hole doesn't go through the body. I have removed the restrictive pigtails & foam on the air filter and put 100 mains in and it goes much better. If replacing the jets check the float levels as the plastic floats are old and if distorted can cause hydroloc

[98valk]

If you really want to know why you heat the carbs, the answer lies in what my FIL explained to me; he was a long-time engineer at the Carter Carburetor company. It seems that when the fuel is atomized into a fine mist, there is a large temperature drop, especially as the velocity in the venturi approaches the speed of sound. This high velocity works for you, in that the fuel is broken into ever finer droplets, which create the best combustion. The temperature drop works against you, as the colder the mist, the more it wants to condense into rain, which is bad for combustion. So, if you heat the fuel a bit, or keep the venturi warm, condensation is less likely to occur. In autos, the manifold was often heated, to keep the mist from forming 'dew', and just dripping into the cylinders, but we don't have a manifold. Thing is, if you heat it too much, the fine droplets in the mist turn into vapor, which also doesn't burn as well in an engine, so you have to balance the amount of heat against the temperature drop; in colder climates, this works well, but nearer the equator, not so much.

it is the vapor that burns and not the mist, you put that backwards.

[wirral_biker]

[/quote]

The hex screws have countersunk heads and are quite long, plenty of room to drill the heads off and use vice grips to remove the shaft of the screw when the pipe is off,  you don't need the screws after its removed the thread hole doesn't go through the body. I have removed the restrictive pigtails & foam on the air filter and put 100 mains in and it goes much better. If replacing the jets check the float levels as the plastic floats are old and if distorted can cause hydroloc

[/quote]

Worth knowing as I may remove those 'heater' hoses next time I have to remove the carbs.  Fired her up this morning and she runs nicely...just a very small crackle now and again, so after a healthy ride to see how she runs, I may back out the mixture screws to 2.0 turns and check again etc.

[WintrSol]

If you really want to know why you heat the carbs, the answer lies in what my FIL explained to me; he was a long-time engineer at the Carter Carburetor company. It seems that when the fuel is atomized into a fine mist, there is a large temperature drop, especially as the velocity in the venturi approaches the speed of sound. This high velocity works for you, in that the fuel is broken into ever finer droplets, which create the best combustion. The temperature drop works against you, as the colder the mist, the more it wants to condense into rain, which is bad for combustion. So, if you heat the fuel a bit, or keep the venturi warm, condensation is less likely to occur. In autos, the manifold was often heated, to keep the mist from forming 'dew', and just dripping into the cylinders, but we don't have a manifold. Thing is, if you heat it too much, the fine droplets in the mist turn into vapor, which also doesn't burn as well in an engine, so you have to balance the amount of heat against the temperature drop; in colder climates, this works well, but nearer the equator, not so much.

it is the vapor that burns and not the mist, you put that backwards.

Actually, the mist presents a better flame front, as it turns to vapor in a more-controlled fashion. If only vapor is introduced, you often get knock or uneven burn. At least, that's what an expert in carburetion told me. This is probably why direct injection is the current darling of engine designers.

[wirral_biker]

[/quote]

Yes, exactly as described, one of the first UK models.   I couldn't get the small ( hex ) bolts out to release the water pipes and get the float bowls off!

[/quote]

The hex screws have countersunk heads and are quite long, plenty of room to drill the heads off and use vice grips to remove the shaft of the screw when the pipe is off,  you don't need the screws after its removed the thread hole doesn't go through the body. I have removed the restrictive pigtails & foam on the air filter and put 100 mains in and it goes much better. If replacing the jets check the float levels as the plastic floats are old and if distorted can cause hydroloc

[/quote]
Hi leathel,
Great details/advice.  I am assuming you left the 'heater' hose off the carbs and simply bye passed from one side of the radiator to the other with some hosing?
Cheers

[Leathel]

Yes, exactly as described, one of the first UK models.   I couldn't get the small ( hex ) bolts out to release the water pipes and get the float bowls off!

[/quote]

The hex screws have countersunk heads and are quite long, plenty of room to drill the heads off and use vice grips to remove the shaft of the screw when the pipe is off,  you don't need the screws after its removed the thread hole doesn't go through the body. I have removed the restrictive pigtails & foam on the air filter and put 100 mains in and it goes much better. If replacing the jets check the float levels as the plastic floats are old and if distorted can cause hydroloc

[/quote]
Hi leathel,
Great details/advice.  I am assuming you left the 'heater' hose off the carbs and simply bye passed from one side of the radiator to the other with some hosing?
Cheers
[/quote]

 I had to go and look it was so long ago that I did mine, Yes left them off but no I just capped the pipes to stop the flow