Hot-Water hoses on the Carbs?

[Gerrit]

I removed the hot water hose from my carbs, as I assumed that the purpose, is purely to prevent icing up the carbs in cold climates.

Down here in South Africa it is warm, winter or summer, thus I do not need the hoses connected to the carbs...

Also...is cooler fuel not better for performance..?

Anyhow, since removing the hoses, the engine seems to be quite erratic, smooth at times, then rough, nothing specific, but it is not as smooth and wheelie popping powerfull as before.

Your thoughts?

Gerrit
http://www.formulagti.com

[Phil-VTwin]

As petrol doesn't start freezing until ~ -72F i don't think they are there to prevent that, the most likely use of them is to maintain a stable temperature of the fuel and carbs by also removing heat.

Best put them back on and see if it cures your problem, if not then something else is causing it, i presume you removed the carbs to take them off?

[Pete.L]

Hmm!
Interesting, I've never really thought about it before. I had assumed the same as you and they stopped iceing. Guess they must also aid the fuel emulsifying and giving an even burn. They are big carbs after all. Do as Phill says and if all is good, lesson learned, leave them on and all is good

Pete.l

[tony.mon]

It might just be the opposite of what you thought; the coolant is there to keep the carbs from overheating from heat soak.

That might cause misfires, if the fuel in the float bowl gets hot enough and starts to evaporate too quickly.

Is that possible?

[Stratman]

I think Mr Honda put them there for a reason, so if it is misbehaving, reconnect them surely?

Carb icing is why they are there and you don't have to get down to -72 to experience it - its all down to vaporised fuel going through the venturis etc and other techy stuff. Some earlier (90's) Kawas can suffer from carb icing in the UK even when it isn't actually freezing.

[goody]

Carb icing is moisture in the air freezing on the internal surface of the carb. It forms a frost on the inside which can block the jets causing the bike to cut out.

[Pete.L]

Carb icing is moisture in the air freezing on the internal surface of the carb. It forms a frost on the inside which can block the jets causing the bike to cut out.

Yep!, had it loads of times. Normally cold damp mornings when it's just a couple of degrees above freezing. Your slow Idle air jets block, neat fuel runs down the inlet and your plugs get fouled. It can be a bitch trying to ride a 125 bhp bike in the frost when you can't let the revs fall below 5k, especially in rush hour traffic.

Tony,
good thought about the over heating. Add that to not letting the carbs get too cold and Honda probably had some very stable operating figures to work with for working out power, performance etc.

Pete.l

[Gerrit]

Thanks for all the advice guys, will put the hoses back this weekend, and see if the "irregular" running stops.

Gerrit

[tony.mon]

. It can be a bitch trying to ride a 125 bhp bike in the frost when you can't let the revs fall below 5k, especially in rush hour traffic.



Pete.l

I had a Honda CB125 S at one point (getting insurance back down after my second ban) and it holed the piston. That'd be the "tuning" then, one piston split from a CB500/4 high comp kit and a 42mm speedway air filter jubilee clipped onto a 22mm carb.

Anywho, hole in the piston, but the funny thing was it would still run if you kept the revs above 6000, you had to run like buggery to bump it but once it was going it would keep running alright.

Except for the oil blowing out through the exhaust, obviously, but with a spare litre each day stuffed down my jacket it got me to work and back until the weekend and I could do the obligatory Saturday rebuild....

[coledog]

As air rushes through the venturi it gets very cold all you have to do is look at the blower top on a drag car it ices up it is just what happens as air is sucked in at a fast pace same with your carbs. you need a physicist to explain it better!

[solorider]

you can get carb icing at 20 deg c,this chart is for planes but it gives you an idea on temperatures and the dew level etc,the icing problem can be at a higher temperature than you realise http://ibis.experimentals.de/images/car ... assl14.gif

[solorider]

Temperature drops of 20 °C (36°F) or more are often encountered within the carburetor, so ice can build up even when the outside air temperature is well above freezing. Perhaps paradoxically, cold winter weather is less prone to icing, since cold air contains much less moisture. A warm day with high humidity is considered the most likely scenario for carburetor icing. Since there is less air acceleration through the carburetor at full-throttle operation, icing is usually not a problem then

[storminateacup]

I have had carb icing on aircraft at +30c it's to do with the moisture content in the air not low temp.