Carb icing?

Question

Riding my bike a few minutes ago, it just died on me, from past experience I think its carb icing! Any ideas how to thaw it out, baring in mind I'm stranded at work

Its a single cylinder, air cooled (obviously) 500cc Cagiva River. Nice bike when its behaving

CJ - I'm riding in Central England, its snowing at the moment.

Answer 1

Phone your dad up so he can borrow his mates big yellow van to come and recover the bike.

Answer 2

Hi,
This really isn't an issue of the type of fuel you are using. Carburator icing is more dependent on the humidity level of the air on the day of your ride. The higher the relative humidity and lower the outside temperature, the quicker carb ice happens. The cooling of the carb throat by evaporating fuel causes the humidity in the air to freeze (not in the fuel) in the throat of the carb.

The easiest fix if this is typical of the riding environment you commonly ride in, you need to make an ajdustment to the air intake by installing a larger carburator. The larger diameter throat will reduce the temperature drop and reduce vacuum caused by air intake.


An alternative would be to have the ability to warm up the intake air. Basicly you can make a butterfly inlet that lets air channel from one of two sources. Source 1: through the air filter (normal channel) Source 2: either air collected off the cylinder head or from a metal channel surrounding a section of the external exhaust pipe. It should be fairly easy to form. What will happen is you will warm up the air entering the throat of the carb enough to melt the ice and prevent it's build-up. Once it melts switch back to source 1. Depending on the day, this may need to be done a few times on a journey. The warmer air will run a litlle richer so you may notice a little temporary loss of power.

There is not many grades of gasoline that are purer and better powered than 100 octane Low Lead Aviation gas and carb icing in airplanes can happen up to 80 F on a summer day. That's how we take care of it is by a dual air source and we watch for an r.p.m. drop at a constant fuel burn.

Otherwise just wait for a lower humidty, higher temp day for your bike ride.

Answer 3

Wow, where are you riding? Alaska?

Are you sure it's not condensation in the float bowls? Sometimes if you have a half tank of gas, and the bike has been sitting for awhile, moisture builds up inside the tank. Then when you fire it up again, the water collected in the tank finds its way into the carbs, that would cause your motor to die out on you.

Ok, let's suppose it's icing....

You certainly don't want to put a torch to the carbs like you do to your water pipes! Not a good idea!! We don't need you blown into the next county.

If you're able to move your bike into a warmer area, that's certainly the best choice. Chemical heat packs or electric heating pads would work too if you're able to get to them.

The only other thing I could possibly think of, and it's a longshot, is to use hot water on the outside of the carbs.

Best thing to do....prevent this from happening. Use a good fuel stabilizer in your fuel during cold months.

Answer 4

The quality of petrol has been decreasing for years, which has been compensated for to some extent by the use of additives to help it burn more evenly however this means that the fuel vaporises at a lower temperature which robs heat from the inlet tract and carb body. Either try using super plus unleaded or the like or use a decent quality additive. Its not a fault with the bike it just wasnt designed to run on the soup they sell today.

Answer 5

Hot towel - wrap it around the carb/s in question - might have to do it a couple of times!

What bike is it - This is usually a Honda problem on their multi cylinder bikes and is caused by the crank vent being fed back to the air filter housing - moisture is vented from the crank and ends up in the air filter box and then pushed into the carbs - I thought Honda had cured this problem - It couldbe applicable to other makes as well -

Answer 6

My dad used to get carb icing in the minivan in the 80's. All we did was pull over and the heat of the engine would melt it in a minute or two. Not sure if that would work with a motorcycle or not.

As far as preventing it I have no idea. Small airplanes have heaters on the carbs to prevent icing so if you can rig a small heater or duct some heat in that area it might help.

Answer 7

I've been told this is caused by modern cr*p petrol; this was never any sort of a problem in the 60s when I used to ride Triumphs in all weathers.Can't think of anything that would be of help right now, but maybe the petrol additive idea may help in the future, or try gassing up on one of the more expensive fuels in the cold weather.

Answer 8

had a similar problem with one of my bikes fuel additive help sort the the problem but the cause was the air intake on the bike ie not getting enough warm air from the engine it was a virago. fun bike to ride but cold weather acted up.

Answer 9

This happened once to an ex girlfriend of mine on her Honda PC50. A helpful passing policeman deduced carb icing and suggested she should pee on the carb! Dressed in all of her winter gear he obviously thought she was a bloke. Worth a thought though - could possibly get you out of trouble.

Answer 10

Normally heatsoak from the engine de-ices the carb jets when you stop. If it doesn't there may be an underlying problem.
To prevent it get some Silkolene fuel additive.

Answer 11

Leave it for a few minutes and it will go again, you can buy fuel additive to stop carb icing just go to any good motorcycle shop.
Good Luck.