My Ninja 250 (don't knock it till you try it), won't idle without the choke on at least part way (after warmup). There is a definate flat spot through the low RPM range, but once you break through it, the bike winds out well. It has been this way since it rolled out of the shed after winter. I have some sea foam carb cleaner in the tank, and while I have not been riding it a lot, things have not really improved. Idle jet clog?

Thanks.

Probably chum in the carbs. Clean em real good and drain the tank. Use stabile instead of seafoam for storage next year.

My Ninja 500 (twice as big as yours ) has consistent problems with the jets being plugged (Kawasaki was too cheap to install a filter), but it seems to have more problems at high RPM than at low. Water and junk in the bottom of the bowls will cause lots of problems, though, so it is probably a great place to start.

Also look into ETHANOL based fuel and what irt does after 2-3 months of sitting. You CANNOT leave that crap in a tank over season. The vehicle ( motorcycle or car ) really needs to be drained and run with ethanol formula Stabil prior to storage

Yup. Idle jets are plugged up. Probably mikuni carbs. My drz does the same thing after sitting.

Just to add to what others have said, the idle jets on these carbs are very small and can be very challenging to clean.

This brings back bad memories of a Honda Rebel 250 that this girl brought in to the British bike shop where I worked for while. Took me three tries cleaning out the stupid carb before it ran right. Never had trouble like that with an Amal.

Spraying carb cleaner and shop air may not do it. I ended up using a strand of soft copper wire to clean the jet.

Hope this helps.

Everything does this after sitting some time.... the smaller the idle fuel circuit the easier it is to get plugged up. so the smaller the enigine the more apt to get clogged the carb will be.....

Are you familiar with and fairly proficient with carbs? Whatever you do, do not soak them in a bucket of carb cleaner or just start spraying it into passages.

Remove the carbs (keeping the two connected to each other) and very carefully remove the float bowls. It's easiest to clamp them upside-down in a vise while you do this. You'll push the pin that the float pivots on out of its position and GENTLY remove the float and needle valve attached to it. This stuff's delicate and cannot be bumped, bent, or pryed on or it'll lose fuel level adjustment.

You'll then be looking at a few tubes and what lookes like sloted brass screws facing straight up. These are your jets. CAREFULLY remove each with the correctly sized slotted screwdriver. They are soft. Take your time.

Get some carb cleaner, compressed air, fine wire (guitar string) and eye protection. Now you can soak those jets and then look through each like an aperture to verify you've got a nice round passage. If not, there's the gunk. Clean them, blow them dry, and replace.

While you've got them out, put your glasses back on and you can spray some carb cleaner into the very tiny passages you'll see in the carb bottom and throat. Chase this with compressed air to make sure everything you spray in comes out somewhere.

Has this bike been rejetted? If not, I would recommend drilling out the EPA caps carefully and removing the idle mixture screws just in case there's gunk there too. Before you remove these screws, you bottom them into their holes and very carefully count the number of turns required. Write that figure down. It'll be the base setting once you go to put everything back together.

If you lived closer, I'd help. Sorry for the novel.

I've stopped winterizing my bike because the spring blues are a pain in the neck. Instead, I set my phone to remind me once a month to run the bike (and our generator). I give it a quick jaunt every couple weeks in the winter which keeps it in much better shape than winterizing and storing, it seems.

Save youself some frustration. Take the carbs off and clean them as above. Put new keys in after you make sure the passages are clean. Running a wire throuh will score the passage on the very small idle jet. Worth the 10 bucks.

Keys= jets. Auto correct.

I actually use a single strand of copper wire out of a thicker wire bundle to chase the jets and since that's softer than brass, I've never encountered a scoring issue. And I generally go really easy into the jet with a twisting motion--real careful like.

Gents:

Thanks for all the info. I was hoping to get out of this easy, so I left the gas on at the tank and drained both float bowls. It seemed to respond, but stalled about a block from my house on the 2nd test lap. I killed the battery trying to get it started and ended up pushing it home.

Battery on charge...will drain float bowls again and try it out. Next step will be jet cleaning.

Sadly, I don't think draining the bowls is going to help you. Very tiny passages are likely plugged. The only way I know of to correct this is a thorough manual cleaning. You can do it. Just take your time and write stuff down/take pics for reference along the way in case you're nervous about putting things back together the way it came apart.

Another thing:

Float bowl screw heads are soft. Make sure you use a good #2 screwdriver tip if you go to remove them. Once you bugger one up, it's a pain to remove the screw. A lot of times, I put a tip in a 1/4" socket and use a 1/4" drive wrench so that I can push into the screw hard with one hand while having the added leverage of the wrench to break them free.

Targatoy has obviously done this before and is spot-on, but for my own gratification I'll add some color commentary.

1. You have a nice motorcycle that I've always liked. Kaw. gets astonishing HP out of that 1/4 liter engine on your bike. The redline is something like 10K. You better believe the tolerances are tight. This means the carburetors are painstakingly designed to atomize fuel properly -- lots of little holes and passages to clog. If you can't get comfortable pulling and cleaning your carburetors, you won't be able to ride your motorcycle very much.

2. Who ever posted the advice to use Stabil all the time is correct. It retards the chemical process in ethanol/gas mixture that creates gummy crud in the gas. Since ethanol is highly reactive to water/condensation, you must also try to be very careful to keep your tank full when not riding it.

3. NAPA has one gallon cans of carb cleaner with their own basket for soaking. Dissemble the float bowl, floats and anything else that is not metal from the carb and drop it in for a couple of hours. Then blow everything out with air.

4. Don't use wire on jets, you really shouldn't need to if you unscrew them. But you will need to use wire on the idle air bypass ports. These are the little holes you see inside the carburetor on each side of the throttle butterfly. There is some really small piano wire you can buy at some hardware stores that is perfect for this. Every one of those tiny holes is actually the end of a tunnel that needs to be clean for the carburetor to work properly.

5. Buy a rebuild kit or just the gaskets so you can put everything back together.

6. EPA covers as mentioned earlier are designed to prevent you from richening the mixture. They are usually caps or studs that prevent the screw from turning. Unlike 914's, adjusting the idle screw affects overall A/F mixture. Your bike might run a little better and cooler with a very, very slight increase of fuel in the mixture. It's best to adjust these on the bike since that is part of the sync process anyway.

7. Pull the carbs out together. There is usually one side of the bike they come out on. Don't take them apart. Make sure you get a good tight fit on the intake boots when you re-install them.

A great thing about those Ninjas is that there's lots of parts available and lots of internet help too. I'd really suggest doing at least some of what Targatoy and I describe. It's just not as hard as it sounds and is the only way to keep those cool machines running. Good luck. Be careful.

Lucked out on this big time (I think). Drained the float bowls a 2nd time today, reinstalled the battery and took the bike out. Smooth idle without the choke after warmup and it pulls strong all the way. Unless something else breaks loose in the fuel system and screws things up, I think it is good to go for the season!

Happy to be riding again. 28HP on a 304lb bike with a 14K redline is just plain fun. Last week I came dangerously close to being "that guy" who has three vehicles and needs a ride to get parts.

Thanks for all the tech support. I printed out responses to the original post for WHEN I end up cleaning the jets...and my winterization next year will involve more than just rolling it into the shed.

Great to hear! I just got done rebuilding a set for a friend on a ZX6R... Just for an FYI you are dealing with KeiHin Carbs! Honda and Kawi's are notorious for them and they are like a Rodchester Quadrajet! "When they are tuned and running, There the best carb out there. When they arent, They're better as a doorstop!" I have been working on them (In my dads motorcycle sweat shop) since I was a kid, they have vacuum controlled throttle jets and are a superb PITA! The vacuum chambers aside from the jet nozzels have to be cleaned as well! When/if you have any other issues take the carbs apart, take the rubber components out such as the top diaphragm and seals and soak the bodies, if you have the ability have the jets ultrasonic cleaned or simply replace them. blow all of the passages out with low compressed air and reassemble. You might want to buy a monometer or you can look up plans on how to build one using clear tube and transmission fluid! However I hope this helps in the future!

Thomas

KeiHin's are fussy to work on, but you have to admire the engineering. Some of those ports are so small that after ten years or so you have to soak the carbs in vinegar to clear the calcium from water vapor in the fuel line.

Don't forget the Stabil.