Carb Problems With Rain

[efi64]

Last Friday I was riding the whole day in rainy weather. As the day progressed I had more and more problems with my Carb slide sticking, until I finally could not continue riding.

I found water on the slide (round slide Keihin). I can only think of the water getting to the slide through the throttle cable. Any tips on how to fix such a problem ?

I have a 1998 Scorpa 280 Easy.

Thanks.

[twhy]

could be a form of carb freeze, try changing your fuel brand..

[efi64]

That's what is weird, I didn't cross any deep water.

I found water on the slide but nowhere else on the carb.

Filter was dry and vent pipes not clogged.

As for carb freezing, it doesn't get that cold in this area of Israel (usually hot as hell)

[g4321]

There is the chance that water is being sucked into the carb via the cable or via the cable fitting/adjuster at the top of the carb. If there is any damage to the outer of the throttle cable tape it up - or replace it, then lubricate the cable with penetrating oil or similar. If there is a gap between the cable outer and cable adjuster it may be worthwhile putting a tight fitting length of fuel pipe or similar over the adjuster/cable interface. If you have too much slack or play in the cable the outer may be resting on the edge of the adjuster, tcheck your cable routing so this does not happen.

I would be inclined to go down the route of water getting in via the air filter or filter duct between the filter and carb. Do you pressure wash your bike and have you forced water into the carb?

The other thing to look at is your fuel - it may be that the water has been present within your fuel/oil mix, its sometimes hard to see water in a 2 stroke fuel and it has got onto the slide this way. On a 4 stroke you dont have oil in the fuel and any water is more likely to stay in the float bowl. Strip and drain your carb, check for leaks, clean and re-oil your filter, seal the cable inlet to the carb and cross your fingures before you go out in the rain again.

[twhy]

That's what is weird, I didn't cross any deep water.

I found water on the slide but nowhere else on the carb.

Filter was dry and vent pipes not clogged.

As for carb freezing, it doesn't get that cold in this area of Israel (usually hot as hell) 

<{POST_SNAPBACK}>

I did know you were Israel, just thought i would mention it as i had a problem on a road bike i used to have, with not a drop of water in sight. the slide would get really wet and start causing problems with running. Condensation and or water droppets in the petrol, the cure was change of fuel brand and a small heater fitted to the carb. the problem was never seen again. The air temp do not have to be cold for it to freeze but it helps.

[efi64]

Thanks for all your answers. I checked everything that was mentioned here, and the only places that that could have let water into the slide is the throttle cable or water in the tank.

I hope that next time in the rain there won't be a problem

Edited December 20, 2005 by efi64

[feetupfun]

The water you found on your throttle slide is probably condensed from the air. The slide can become cooler than the "dew-point" of the air in high humidity conditions due to the cooling effect of evaporating fuel from liquid to vapour as it enters the airstream at the throttle slide. It is the relative humidity of the air that is important, not the temperature.

The humidity of the air you are riding through will be the determining factor for a given bike and fuel combination. You may have formed ice from the water which jammed the slide if it got cold enough but I doubt this happened. It is more likely that the water/fuel/oil mixture was gooey enough to stick the slide even without the water freezing.

Petrol fuelled cars with carburettors usually have inlet heating systems using the engine coolant to prevent this effect causing problems in high humidity conditions.

[efi64]

So, there is no way to prevent this ? Maybe insulate the the upper part of the carb ?

[feetupfun]

Warm greetings from a warm part of Australia in midsummer (phew not much riding going on at present)

If you want to continue to ride the Scorpa Easy in your warm Israeli rain, I suggest you try a different fuel. The worst fuel for you to use would be a petrol/ethanol blend because the ethanol part increases the refrigeration effect compared with straight petrol.

Insulating the carby would make it worse because in high humidity conditions, carbies need a heat source to keep them above the dewpoint inside. In the case of your Scorpa the heat comes as radiation and convection from the exhaust system and the engine. If you insulate the carby, it will get even colder inside.

Sorry I can't recommend a fuel for you because they vary so much around the world in their properties and composition.

We generally use unleaded car fuel of about 94RON containing no ethanol in our trials bike premix. Some of the modern trials bikes which are a bit sensitive to poor fuel benefit from using ELF unleaded racing fuel because the petrol bought from car petrol stations is variable in quality.

[efi64]

Thanks, I'll try different types of fuels, although in general the fuel here is not so high quality.

[efi64]

After that eventful ride in the rain the bike doesn't want to start properly!?

I have cleaned the carburetor and the air filter. I have even replaced the gas in the gas tank, but the bike only starts after about 100 kicks!

After I get it started and cleaned up from being flooded up by so many kicks it works properly and starts on the first kick, but if it cools down for an hour, again it's impossible to start !?

There is a spark on the plug, gas reaches the plug, and compression seems normal, the ignition coils were dry after the rainy ride.

What am I missing?

Anyone has any idea?

[neonsurge]

OK, this is a long shot, but might there be moisture elsewhere in the carb? Maybe in the bowl and/or floats - might that be causing the floats to stick? I only mention it since I recently had a cold starting problem on my Beta and I traced it to the fact that I'd recently adjusted the float level in an attempt to cure the classic Beta fuel dribbling problem and they it wasn't allowing enough fuel to flow into the carb to start the engine from cold. The quick and easy solution is to rock the bike from side to side a couple of times before kicking it over. Might be worth a try.

[feetupfun]

I'm assuming a few things here:

You are turning the fuel off at the tap when you stop the engine.

Your carby float bowl overflow hose is routed downwards.

Your carby float bowl overflow line is not blocked or kinked.

If you have a problem with the float needle not sealing off and the excess fuel can't get out the float bowl overflow line, it will flow into the crankcases, flooding the engine. I have seen the crankcase so full due to this problem on one of my bikes, it was dripping out the exhaust pipe joint.

Note there is also the possibility of the fuel tap allowing fuel past even when it is shut (easy to test).

If you are using fuel with ethanol or another alcohol in it, all sorts of corrosion problems can occur with metal components exposed to the fuel.

David