2011 Ninja 250 stalls when given too much gas

[GregoryC4]

After taking my bike out from winter storage, it took a while but I finally got it started. It starts right away even without the choke (although low rpms). However, when I try and give it gas with it idling at 1500 rpms, the rpms will drop and the bike will stall if I gave it too much gas. If the choke is on however, if I give the bike gas gradually I will be able to take off. Any ideas on how to fix this? I want to try and run some sea foam through it and I really don't want to take apart the carbureator. Thanks for your help.

[The Red Scourge]

I've had similar problems after letting the bike sit with old gas in it. Your jets are probably clogged. From what I understand it's most likely the pilot jets. That was the issue with mine. Sea Foam might work if it's not too bad. I had to pull the carbs and clean them (twice actually since I half-assed it the first time). I would try Sea Foam first but that's just my opinion. I'm sure someone with considerably more experience will chime in here shortly.

I'd also suggest heading over to the "New Members" area and introducing yourself. Tell us about yourself, your bike and level of riding experience. It helps us get to know ya a bit better.

[DaBlue1]

Originally Posted by GregoryC4

... It starts right away even without the choke (although low rpms). However, when I try and give it gas with it idling at 1500 rpms, the rpms will drop and the bike will stall if I gave it too much gas. If the choke is on however, if I give the bike gas gradually I will be able to take off.

Are you letting it warm up properly?

Your engine idle speed should be 1350 +/- 50 rpms. The engine should be completely warmed when it is adjusted.

Use the choke!
2000-3000 rpms is a common idle speed range for when the choke is on. They key is reducing the amount of choke (small increments) during the warm up until the bike can maintain a steady set idle speed on it's own. It is also acceptable to ride off with the choke on a short distance until the bike is properly warmed.

[The Red Scourge]

It also sounds like your bike is running too lean. It might be worth it to pull the carbs just to futz with the mixture screws. After I set mine to 2.5 turns out it never needs choke even from a dead cold start up.

[GregoryC4]

Wow! I'm stunned by the amount of replies in such a short time. Thanks guys. I will try sea foam for one more tank of gas, if it doesnt clear up in a week or so, I will pull out the carbs. Another question though: I tried pulling out the carbs yesterday, I got all the way down past the tank and up to the carbs. But when I got down to the carbs, they are connected to the airbox and I couldnt figure out how to move the airbox back to take out the carbs. Can someone explain to me how I can move the airbox back just enough to take out the carbs? Thanks guys.

[DaBlue1]

Originally Posted by GregoryC4

Can someone explain to me how I can move the airbox back just enough to take out the carbs? Thanks guys.

Directory of all 250R DIY threads on Ninjette.org
DIY: Removing the air filter box

[csmith12]

The process is different depending on what year 250 you have. Whatcha got? pregen or newgen?

If you have a pregen, there is an awesome DIY video that was made on removing the carbs. I tried to find it for you, but failed. Maybe someone has the link handy if it will help you.

Good luck!

[GregoryC4]

I have a newgen 250. I also looked at the DIY for the airbox removal, but I can't understand how he disconnected the airbox from the carbureator . I don't want to cut the boots to remove them.

[DaBlue1]

Originally Posted by GregoryC4

I have a newgen 250. I also looked at the DIY for the airbox removal, but I can't understand how he disconnected the airbox from the carbureator . I don't want to cut the boots to remove them.

You have to remove the snorkel, unbolt the airbox from the frame, unscrew the clamps on the carbs boots and slide the airbox back. It's not much, but you should be able to wrestle them carbs out.

Before you rip into the carbs, try doing the basic stuff first to make sure the bike is ready, fresh gas, plugs, oil, proper technique in warming up the bike and setting the idle speed correctly. it's been sitting for a while, if you got it to run without the choke, ride a little bit with the choke on. Ride it til the engine is nice and hot, then see if there is any difference. Keep in mind the bike will run differently in colder weather than it does in warm. Gas does not vaporize well in a cold carbed engine. It will run better as it warms. Be patient when starting. It may save you some unnecessary work.

[GregoryC4]

Originally Posted by DaBlue1

Y

Before you rip into the carbs, try doing the basic stuff first to make sure the bike is ready, fresh gas, plugs, oil, proper technique in warming up the bike and setting the idle speed correctly.

I put in some fresh gas and its running better already . i was revving it at 1500rpms without any delay or drop in rpms. Awesome! I changed the oil before I stored the bike away (although i did have it running to burn all the gas for a little while) is it worth changing the oil again? Thanks

[DaBlue1]

Originally Posted by GregoryC4

....I changed the oil before I stored the bike away (although i did have it running to burn all the gas for a little while) is it worth changing the oil again?

You should be fine as it is.

[Racer x]

It sounds like you are on your way. But for others pulling bikes out of storage.
This is what I would do.
Let the bike warm up completely. Then slowly open the throttle.
Idle is the idle screws. Then its the idle screws and pilot jet that together supply fuel. After that its the pilot jet and the main jet in relation to the needle that is rising out of the main jet. More throttle movement and the pilot jet is out of it and its the needle and main. Once you get to full throttle the main jet is supplying all the fuel. Each part or jet is responsible for different levels of throttle opening. If the vacuum slides are truly working then its some restriction in the jets. Could be bad gas also. If the fuel is old replace it.

[Alex]

Agree with almost all that has been posted so far. But I wouldn't rip into anything until you take it for a ride. Sometimes all it needs to clear its throat is a good 20 - 30 minute ride where everything gets fully up to operating temp. If the bike is still having issues afterwards, only then start working on the troubleshooting suggested here.

[cadd]

If you don't have to, I agree with the other guys, don't take the carbs off. It's a whole lot of work if you have the stock airbox!!!!

I took my carbs off to clean and I'm in the process of putting everything back together. If you need some reference, the thread I started (asking for help) has a great deal of links (provided by many knowledgeable members here) that helped me out big time!!!

http://www.ninjette.org/forums/showthread.php?t=173028

[mgentz]

the cheap and easy "fix" can sometimes be sea foam. If your carbs do not clear up after running for awhile with new gas, and/or sea foam, then it may be time to pull them apart and clean them.

[SuperAmp13]

Originally Posted by GregoryC4

I put in some fresh gas and its running better already . i was revving it at 1500rpms without any delay or drop in rpms. Awesome! I changed the oil before I stored the bike away (although i did have it running to burn all the gas for a little while) is it worth changing the oil again? Thanks

Hi Greg! Is it cold where you live, and more importantly is the bike stored somewhere it gets cold?

I have this problem from year to year. Luckily I store mine in my garage attached to the house, so I am able to get out and warm it up once a week or so, but what happens if you don't run it over the winter and the parts get cold is they will contract and distort. This causes the bike to run incredibly lean or rich, and seem like something is wrong.

It seems like you worked out the isse at this point, but I would say if you run it once a week or every few weeks just to keep everything moving you shouldn't have that problem next year.