Coolant hoses on Carburator

[Bimbam]

Hi.
My brother got a leak on a coolant hose (See picture)
We have replaced the hose and now it is working fine.
My question is: What does the coolant do on the carbs?


Bye the way, the inlet rubbers on the carbs dont look good, is replacement needed?

[sinto]

As far as the coolant on the carbs, it's just water based if you've mixed it with anti-freeze etc, a good wash will get rid of any residue providing it's just the outside of the carbs, i.e. the casing? that it went on.

The rubbers do look iffy, I'd certainly change them.

[Freck]

Hi.
My brother got a leak on a coolant hose (See picture)
We have replaced the hose and now it is working fine.
My question is: What does the coolant do on the carbs?


Bye the way, the inlet rubbers on the carbs dont look good, is replacement needed?

I take it you mean why is there coolant going to the carbs. I can't say for definite but some manufacturers do this to prevent carb icing.
The Venturi effect of the jets/carb intake sucking in air can cause ice to form and cause fuel starvation. The water jacket in the carb will warm it to stop the ice forming.


As for your rubbers, yep, I'd definitely get some new ones


Steve

[fazersharp]

I never knew what that hose was thought it was some sort of breather.
The rubbers look fine --- in that nothing to worry about yet as they are only very fine cracks and will need to get much much worse before the cracks are all the way through

[unfazed]

There is supposed to be a small spring type hose clip on that pipe like the one on the small pipe on the right side of the radiator.

[rajoana]

Hi, my very 1st post here in this forum.


basically its meant for winter conditions.


if u dun experience that, u can do a by pass n block that outlet altogether hence allowing cooler air for combustion. which make the engine slightly more responsive.

[sinto]

Hi, my very 1st post here in this forum.


basically its meant for winter conditions.


if u dun experience that, u can do a by pass n block that outlet altogether hence allowing cooler air for combustion. which make the engine slightly more responsive.

Welcome rajoana,
Interesting first post!
What do you class as winter conditions? Where would you block the pipe off?

[rajoana]

Hi, my very 1st post here in this forum.


basically its meant for winter conditions.


if u dun experience that, u can do a by pass n block that outlet altogether hence allowing cooler air for combustion. which make the engine slightly more responsive.

Welcome rajoana,
Interesting first post!
What do you class as winter conditions? Where would you block the pipe off?

Well i never experienced winter myself before. I m from Singapore its tropical climate hot and humid all year around.


have done this to my previous rides and even my current car hence i m able to share the experience of a more responsive engine. probably u might only feel the effect if your ambient temp is above 20 celsius at least.


My guess is temperature probably below 10 deg Celsius might need this coolant hose to warm the air for combustion.


probably i would need to take some pics to illustrate the rest.

[sinto]

Well i never experienced winter myself before. I m from Singapore its tropical climate hot and humid all year around.

Lucky you

if your ambient temp is above 20 celsius at least.

Not in foccin Scotland

below 10 deg Celsius might need this coolant hose to warm the air for combustion.

Ahh, I might have to put it back on after summer, that'll be the two days we get mid July

probably i would need to take some pics to illustrate the rest.

Pics of everything always a good idea on here

[Paulfzs]

carb heaters (Y)

[rajoana]

Well i never experienced winter myself before. I m from Singapore its tropical climate hot and humid all year around.

Lucky you

if your ambient temp is above 20 celsius at least.

i wish my country was cooler 

[darrsi]

It's called the "Carb Heater Circuit" and is designed to create a bit of heating by channeling hot coolant around the outside of the carbs to try to prevent the effects of carb icing in winter (or summer in the UK ).


My bike suffered from it when i first got it, but fortunately when i phoned my mechanic when i was stranded by the roadside he knew the symptoms that i explained and he told me what it was.


You're better off Googling or YouTubing it for a better explanation than i could give, but with me i'd leave home for work and about a mile up the road in exactly the same spot my bike would suddenly run very rough, and i'd have to pull over and keep the engine running by revving it as best as i could.
The heat of the engine would then melt the ice in the carbs and i could then be on my way, but that could be a good 10-20mins later so was a tad annoying, and embarrassing.
It was a more common occurrence when there was moisture in the air and the temperature was roughly between 0 to 5 degrees.


I tried buying the recommended treatment, which was a cap or two of Silkolene Pro FST but that made no difference whatsoever.


Then after a bit of research i found that a lot of people used 99% Isopropyl Alcohol in their fuel tank as a way of combating the problem, at around 1% of the fuel tank size, so a 20 litre tank would need 200ml. 


Not only does the alcohol lower the freezing point, but will also bind with any water/moisture in your fuel tank and burn it off as fuel.


I still use it every 2 or 3 tanks of petrol during winter just to keep the tank moisture free, and it makes no difference to the performance of the bike plus does no harm to any pipes, etc, as it's so diluted.


Those carb heater pipes are very thin though and the channels have a reputation for getting clogged up (so my mechanic tells me) so it's another good reason to try and have a well kept coolant system.
Doing a proper clean out using Radflush every 12 to 18 months will certainly be a major benefit to the engine and prevent clogged waterways which in turn causes overheating and then more serious problems.
A good working airtight coolant system shouldn't even need to be touched, and the coolant level in the expansion tank should be the same more or less every time once the bike has cooled down, although you may lose a tiny bit in very hot conditions. 




NOTE: Carb'ed propellor planes suffer from carb icing too, unfortunately they don't get the comfort of standing by a supermarket waiting for the ice to melt in their engine, but do have their own way of heating up the carbs. 

[Punkstig]

As above- to prevent carb icing in winter, and to mix this post with another it's yet another reason why the fzs600 cooling system is one of the best ever- when running correctly there's no over heating in summer and zero carb icing in winter, I've not known any other bike to cope with both hot and cold so well!

[Jules-C]

Mine also suffered from the carb icing misfire and the Silkolene fuel treatment also had no effect. Got used to it ( only a problem when starting from cold in sub zero conditions, no problem once bike was garaged) and knew once misfire started just had to stop engine for a minute or so and problem gone till next cold start.

When o-rings on coolant pipes exiting the back of the cylinder head started leaking had to take carbs of to replace the o-rings and found the carb heater pipe blocked. Managed to blow them clear with a footpump without dismatling them.  Once everything was back together again the carb icing misfire was gone.

Checking the way the pipes connected the carb heater only has coolant flowing through when the thermostat is closed.  This avoids the carbs being heated to 80 or 90 degrees once engine warmed up

[darrsi]

Mine also suffered from the carb icing misfire and the Silkolene fuel treatment also had no effect. Got used to it ( only a problem when starting from cold in sub zero conditions, no problem once bike was garaged) and knew once misfire started just had to stop engine for a minute or so and problem gone till next cold start.

When o-rings on coolant pipes exiting the back of the cylinder head started leaking had to take carbs of to replace the o-rings and found the carb heater pipe blocked. Managed to blow them clear with a footpump without dismatling them.  Once everything was back together again the carb icing misfire was gone.

Checking the way the pipes connected the carb heater only has coolant flowing through when the thermostat is closed.  This avoids the carbs being heated to 80 or 90 degrees once engine warmed up

You wouldn't have got carb icing when starting the bike, and there's less moisture in the air at sub zero so that sounds unlikely as well.
Plus you don't stop the engine to get rid of icing, you keep it running parked up to melt it.

[Jules-C]

My poor explanation trying to cut down length of post.  Carb icing would start to affect low speed running about half a mile after starting in sub zero or very close to zero conditions. It would slowly get worse for the next mile or two until it got to the point when the bike would cut out whenever the revs fell below 4 to 5 thousand rpm. Great fun trying to drive on icy roads in first gear with 6k revs and every boy racer trying to race you because your sitting at the lights revving the engine.  That's when you find out if you turn engine off when you pull up at lights when you start it again the problem has gone. 

Cleared out the carb heater tubes and problem never once reoccurred.  If you got an explanation that doesn't involve pilot jet icing I'd like to hear it.

[darrsi]

My poor explanation trying to cut down length of post.  Carb icing would start to affect low speed running about half a mile after starting in sub zero or very close to zero conditions. It would slowly get worse for the next mile or two until it got to the point when the bike would cut out whenever the revs fell below 4 to 5 thousand rpm. Great fun trying to drive on icy roads in first gear with 6k revs and every boy racer trying to race you because your sitting at the lights revving the engine.  That's when you find out if you turn engine off when you pull up at lights when you start it again the problem has gone. 

Cleared out the carb heater tubes and problem never once reoccurred.  If you got an explanation that doesn't involve pilot jet icing I'd like to hear it.

Turning the engine off at lights makes no sense?
Keeping the engine running, albeit roughly, whilst not moving creates the general bike heat needed to melt the ice, without any air cooling to hinder it.
And in sub zero conditions there is very low humidity so it rarely happens then anyway?

[Jules-C]

Keeping the engine running keeps a flow of cold air flowing through the carb over the small ice crystals allowing them to grow, hence the problem getting worse and worse as you continue to ride. Stopping the engine means the heat from the cylinder head can set up convection current in inlet tract allowing slightly warmer air to reach the carbs and melt the ice crystals.

Yes it doesn't happen often and never if you have bike garaged, even a cover over bike makes a big difference. 

But if it wasn't a problem they wouldn't have tried to solve it with the carb heaters.

[darrsi]

My bike was always garaged at night, but since i started plying my bike with booze every now and then in winter it has never happened since. 
I think having a moisture free fuel tank probably helps a lot too.

[rajoana]

Went down to look at my bike earlier.


the 1st pic posted of the coolant tube is actually not the main one. that is just share the coolant from carb 1 and 2. see in the pic carefully slightly on the left there is another hose coming out....that links 2 and 3. and from carb 3 another hose to 4.the 2 main hoses that supply the coolants to heat the carbs are one on the right side the other i think on the left but more inner.

try to post pics soon. not too gd at doing this...pic uploading

[rajoana]

these are the inputs and outputs

not working.....try something else.

[Jules-C]

To answer your original question yes you could block/disconnect the carb heater hose without any problem or damage to the carbs/cooling system or any other part of the bike.

But there would be no real benefit because once the thermostat has opened as the bike warms up there is effectively no flow through the carb heater pipes. You can confirm this by checking the temperature of the pipes at the carburetors and they never even feel warm to the touch.