2003 EX250-F has engine problems in the rain

[losmurfs]

When I ride in a heavy rain at or below 50 mph I have no problems. Between 50 mph and 75 mph in the rain the engine tries to die but I can keep it running as long as I keep playing with the throttle. Above 75 mph it seems to run smoothly but sounds a little funny (compared to 75 and above in dry weather). Is this an electrical problem that occurs when something gets wet? or are my air filters getting wet thus restricting air flow? is this normal on all third gen 250s? or is there something I can do to my Ninja to make it run as well in the rain as it does in dry weather? Anything that the Weather Channel would classify as light rain or less does not affect my Ninja. Anything classified as heavier than light rain does mess up my ninja but only at interstate highway speeds.

Any help or insights will be greatly appreciated.

Thanks (I want to ride 365 days a year)

[Skippii]

What's the ambient temperature? If it's cold (40s or so) these carbs can get ice crystals to form in the venturi. Usually only happens with K&N or other higher-flow filters.

[losmurfs]

I've operated my Ninja down to 29 degrees F. The coldest rains where I experienced problems was 42 degrees (only ridden in light rain below 42 degrees), but I've also experienced issues at 55 degrees.

[Skippii]

Hm...not sure what the problem is, then.
This is an explanation of the issue I was talking about
http://faq.ninja250.org/wiki/What_is_carburetor_ice%3F
But I'm not sure that's relevent if it's happening at 55*.

You mentioned air filters, do you have something different than the single stock filter?

And, have you taken it out after a rainy ride to see if it's wet?

Any other electrical issues present?

[losmurfs]

I just went out to my garage and snapped a photo of my air filters. I've only had the bike a month. It had at least two previous owners. I've ridden it to work 5 days a week since I got it. Today was the first time I have ridden in it in anything harder than light rain at less than 60 degrees (I've ridden below 30, but not in the rain). It could have been less than 45 this morning. Do you know where I can get hourly weather history for today for the 40258 ZIP? The previous owner replaced the gas cap assembly so who knows what else is not stock.

[indr]

AFAIK, the older Ninjas had air boxes, not those pods.

Besides, the filters look dirty and damaged. The moisture from the rain is probably dampening the cloth/paper and making it harder to take in air. Maybe some moisture is going into the engine?

Replace those ASAP before a hole rips in em and the dirty intake causes damage.

If you really want to, you could reinstall the stock air box. But, from what I've read, it's a pain to take it out in the first place, so putting it back in might be worse.

Easiest would be to replace them with a proper size dual layer filter from here: http://www.unifilter.com/online%20ca...universal.html

Easy to put on and easy to take care of.

[indr]

And consider re-jetting the carbs after installing the new filters.

[choneofakind]

Airbox really isn't as bad as people keep saying it is. just takes some patience.

another option for pods is the K&N R-0990 filter. It goes over both carbs instead of having to buy one filter for each carb

[losmurfs]

I'll see my mechanic on Saturday to get a quote on restoring to original factory air cleaner spec, and then if I can't afford that, just buy a new dual carb filter. If I were todo the work, how do the filters I have come off?

[choneofakind]

there should be some of thoes clamps that you tighten with a screw holding the filters onto the carbs right now. just loosen them and pop them off.

airbox. $10.00

[Skippii]

Those pods are not stock. They are an aftermarket improvement. Why would you want to downgrade to stock?

They look very similar to my K&N pod filters. Maybe they're an old version of the K&N, or a similar brand.

Anyway, pod filters are a good thing, but like any air filter on any vehicle, they need to be kept clean.
Even more importantly, they need to be kept OILED, since it's the oil on the fabric that actually traps the dirt. That would also repell rain.

Yes, bikes need to be rejetted with higher performance pod filters. That should have been done when the previous owner installed them. If your bike runs completely horribly in ANY weather, then it probably hasn't been done. If it does run well in good weather, than it's already been done and you don't need to worry about it.

New jets and shims usually cost around $6 or $7, so it's not the end of the world if it hasn't been done.

Your filters need to be cleaned and oiled as soon as possible. That will probably solve all your problems, and greatly increase engine life.

[Skippii]

Originally Posted by choneofakind

Airbox really isn't as bad as people keep saying it is. just takes some patience.

I disagree. It really is that bad, and should be removed ASAP and replaced with pods like the OP currently has. Just my opinion, of course.

[losmurfs]

My main goal is all weather reliability. I bet I was experiencing carb icing and then the temperature on my way to work was just colder than I thought. Would a K&N R-0990 fit without any modifications to the bike? K&N does not claim to make filters for EX250-F.

[cbdallas]

If the carb has been jetted to run with these pods, would it run too rich if he goes back to the airbox?

[choneofakind]

yes it would need to be rejetted to work with the airbox. luckily we know the jetting requirements for a stock bike though since that's how it came from the factory.

and yes the K&N R-0990 works on our bikes http://faq.ninja250.org/wiki/Which_a...e_Ninja_250%3F

and yes the OEM air box does a great job at keeping out water. That's what it's designed for. if you go the airbox route, get some Keihin (or keihin knockoffs) 105 jets from http://jetsrus.com/a_jet_kit_street/kawasaki_250_EX250_Ninja.htm"] and then take the washers off your needles (or if you have adjustable needles from a jet kit, put them on the middle position) and voilah, stock jetting with a stock intake.

[JLinde1339]

I'd have to agree with all the above, except going back to the stock box. LOL.

So its fine in dry conditions, sounds like the bike was prolly re-jetted. Those pods do look wretched, so replacing them isn't hard and you won't need to mess with the jetting if you replace them. Maybe you will if the cleaner filters wind up pushing you into a lean mixture. May also be true that the dirty filters emulated a similar air flow as the original airbox, since the dirt and grime restricted your airflow. In which case, new pods would make you lean IF the carbs are still at the stock setting. If it were me, I'd replace the pods first, then see how it runs, and adjust the carbs if necessary.
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[choneofakind]

Originally Posted by JLinde1339

I'd have to agree with all the above, except going back to the stock box. LOL.

but if the issue is getting possibly carb icing, then the airbox putting less air into the carbs will significantly lower the chance of getting icing. but on the other hand, if all the oil has worn off those pods and they're now letting in tons of water, then a new set of pods should do it

[Skippii]

Originally Posted by losmurfs

My main goal is all weather reliability. I bet I was experiencing carb icing and then the temperature on my way to work was just colder than I thought. Would a K&N R-0990 fit without any modifications to the bike? K&N does not claim to make filters for EX250-F.

Start by cleaning and reoiling the pods you have. If they get clean and and there's no tears in the fabric, you should be good.

When properly oiled, they won't let in all that moisture that's making your bike perform poorly.

[JLinde1339]

Last I checked, water freezes at 32*F. How would icing on the carbs occur at 50-75, which is where the OP said the problems were, not at sub-50's?

[choneofakind]

It's all about air temp/humidity/pressure. Carb icing really only occures when the conditions are JUUUUst right.

quick reference on carb icing

[Skippii]

Originally Posted by JLinde1339

Last I checked, water freezes at 32*F.

At sea level pressure of one atmosphere, yes. The whole point of a venturi in the carb is to speed up air flow, which changes the pressure.

[FrugalNinja250]

Originally Posted by JLinde1339

Last I checked, water freezes at 32*F. How would icing on the carbs occur at 50-75, which is where the OP said the problems were, not at sub-50's?

You know how you can take a spray can of something like carb cleaner and it feels room temperature, but when you spray it the spray comes out really cold? What's happening is that whenever pressure in a gas drops (such as from high pressure in the can to low pressure at the nozzle) the temperature drops also, since pressure and temperature are related. When air goes through a carburetor it goes through a venturi whose purpose is to drop the air pressure and suck fuel vapors from the bowl via the jets and air bleeds. In addition to that, when the fuel evaporates into the air flow it cools it off, exactly like what happens when you blow on wet skin. These two conditions, low pressure and evaporative cooling, can cause the backside of the carburetor throat to drop below the freezing temperature of water for that pressure, and thus frost will form because all air has moisture in it. The higher the humidity the worse the problem.

[Skippii]

Boyle's Gas Law sucks.
Charle's Gas Law blows.
Geology rocks.

[choneofakind]

bah dum psssh

[JLinde1339]

Vaguely remember V=T/P from chemistry class, but that was over half a lifetime ago. LOL. Anywho, Frugal pretty much summed it up in a way that makes sense to me. The spraycan part tho, I think is caused more by an endo/exothermic chemical reaction more than anything. Sorry. I's not so good in chemistry. Physics was more my thing. LOL
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[choneofakind]

Originally Posted by JLinde1339

VThe spraycan part tho, I think is caused more by an endo/exothermic chemical reaction more than anything.
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there's no reaction going on in that case though. The can is under high pressure, so the molecules don't have space to move as much, which means that their average velocity is lower; this means that the temperature is lower. movement of molecules means temperature (in a nutshell). when you spray the can, you feel the cold because there's not enough time for the molecules to come back up to room temperature. So for a brief time, you're feeling the temperature of the inside of the can.

same thing happens when you use an air compressor, and open up the blowoff valve. It's cold because of the high pressure restricting the movement of the air molecules

[Skippii]

Originally Posted by choneofakind

there's no reaction going on in that case though.

This is correct.

The can is under high pressure, so the molecules don't have space to move as much, which means that their average velocity is lower; this means that the temperature is lower. movement of molecules means temperature (in a nutshell). when you spray the can, you feel the cold because there's not enough time for the molecules to come back up to room temperature. So for a brief time, you're feeling the temperature of the inside of the can.

This is not.


Gas gets hot when you increase pressure. That's what causes ignition in diesel engines.
Gasses get cold when you decrease pressure. If you take a propane canister and release gas quickly, the bottle with frost over as it sucks heat from the ambient air.

[FrugalNinja250]

My metaphor wasn't completely correct. Some of the cooling effect comes from liquid evaporating into gas at the nozzle, same as with a propane bottle being used although in that case the liquid is evaporating into gas at the liquid/gas interface inside the bottle. Whenever a liquid goes to gas it absorbs a tremendous amount of heat, which is the basis of refrigerant-based air-conditioning systems. Take a gas, like Freon, and compress it. This adds heat. Run the high-pressure gas through a heat exchanger to lose the heat, the gas, still under pressure, condenses to a liquid. Run the pressurized liquid through an orifice or other metering device to drop the pressure substantially and the liquid evaporates, run the evaporating liquid through another heat exchanger and massive heat is absorbed as it "boils" back to a gas. Rinse, lather, repeat.

FWIW, sometimes I get too elaborate with my answers, sorry...

[choneofakind]

Originally Posted by Skippii

This is not.

oops. PV=nRT. my b. Raise P, hold V and n constant, T will rise. derp.

[JLinde1339]

Okay, I was thinking something was backwards there. LOL. If the above was true, there'd be no steam when you boil a pot of water. This all makes sense, but I still don't think the changes in volume or pressure within the carbs would be enough to cause icing with the ambient temp still being above 50*, which is where the OP was having the issues.

Another topic derailled by science.

Stay on target...stay on target........ XD
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[choneofakind]

I googled carb icing. It says that it is possible.

http://www.sacskyranch.com/crbice.htm

[Felipe the Ant]

.....To go back on topic lol, how long has it been since the bike has had a tune up? Old spark plug wires can cause an engine to run like a bag of **** once they get wet. Maybe they only get wet when you get up to speed?

[losmurfs]

All I did was buy a used air cleaner box off of Ebay, restoring it back to factory specs as far as air filter is concerned, no tune up of any kind, and from December on hasn't iced up.