What is carb icing?

[gh0st]

Keep hearing this phrase around and about but dont know what it means.

Engines really are not my thing apparently...

[paolow]

gh0st said:

Keep hearing this phrase around and about but dont know what it means. Engines really are not my thing apparently...

Happens when the weather cools down. as the air enters your venturis it speeds up and can chill enough for moisture held in it to not only separate, but also actually freeze on the inside of your carb. the fuel supply is blocked and the engine will stall. this is why cars/bikes often have a warm air system on the filter. it not only speeds warming up times but also provides enough warm air to stop your carb freezing solid.

[rumpelstiltskin]

I had this problem with an old Beetle,you could actually buy a small electric blanket thingy for your carb:-)Got it's live feed from the automatic choke,this warmed up the base of the carb quicker.

[GreenV8S]

Carbs get a lot of cooling from fuel evaporation. In cold conditions this can lower the temperature of the whole assembly to below freezing. If there is any moisture in the air it will then freeze on the outside of the carb to form a layer of ice. This can be enough to freeze the throttle assembly solid if you have been cruising for a while on constant throttle, which means you take your foot off the gas and the engine keeps going. Stamping the throttle pedal is usually enough to break it free of the ice, assuming you haven't run out of road in the meantime!

Edited to add: not a problem with fuel injection engines since these don't get the evaporative cooling in the throttle assembly.

>> Edited by GreenV8S on Thursday 2nd December 13:07

[DennisTheMenace]

Kawasakis are renowned for it due to the ram air , although i never had a problem even in -4 tempratures

[rsvmilly]

Many years ago my Dad had a Vauxhall Viceroy (as rare as hen's teeth) which used to suffer from carb icing. It would just gradually lose power until you had to pull over. Once you'd stop, the ice would melt and away you could go. I believe it mainly happens just above freezing - below freezing, there is little or no moisture in the air.

[Mark in Ireland]

Air cooled ducatis and Harleys are reknowned for it, if you rubber mount the carbs on a Norton ot'll do it also. Its a pain in the neck when you are following the snowplough over Shap on one cylinder trying to hold 6000rpm just to keep the engine going!