Ninja bogging down when I give it throttle

[jschnetter]

So i'm a new rider and I have a 2011 250r. It ran fine when I first got it but I had to give it some TLC because the previous owners weren't the best to it(dropped it and broke some external stuff). After a while of riding it every day I noticed that when I would give it throttle from a stop the engine would bog down. Pretty much what would happen is I would give it gas and the RPMs would drop VERY low, practically to nothing, so I would roll completely off throttle and try again and that would usually get it going. I asked my local mechanic and he suggested getting the carbs cleaned because it sat in a garage for a few months. I don't have extensive knowledge on the carbs and rely on this for all of my transportation needs so I took it in and had them cleaned out as well as having my chain tightened because it was very loose. He told me the carbs weren't very bad and they adjusted the idle on it to around 1300. The bike idles much nicer now, however I was just riding back from the store and my bike did its whole bogging down thing again. Im very frustrated now because i've put a lot of money into repairs and improvements. Does anyone have any suggestions on what might be the problem if it isn't my carbs.

Ps. I have a slip on exhaust on(don't know if that makes a difference) and i've changed the engine oil, oil filter, and the air filter out for new ones. I've also got about 6,800 miles on the odometer.

[Burphel]

You aren't running with the choke on, are ya? I had similar symptoms on my first bike and after some investigation learned that I'd been using it completely backwards. I have a 300 (FI = no choke), so I don't know which way is which on the 250, but try reversing how you've been using it and see if life is better.

[jkv45]

Because it was running fine, then it wasn't, I would look at the gas. Gas goes bad, and adding fresh gas to bad gas doesn't help. Gas also picks up condensation if the temps are changing and the level in the tank is low.

With a situation like yours I will always drain the tank and floatbowls completely and refill with fresh gas (87 octane no ethanol if available) before taking things apart.

Is the tank clean and free of rust? Look way down at the bottom. If there is rust visible it may be enough to cause problems. Cleaning the tank and adding an inline filter stops the rust from making its way down to the carbs and plugging the jets or causing the float valves to not seal.

If you drain the floatbowls and catch the gas you can look for water or other contaminants in the gas and have a better idea of what you may be dealing with.

If that's not the problem, you can try running a strong fuel system cleaner like Techron Concentrate at 1oz per gal for a tank or 2. It's not going to clear major obstructions in the carbs, but it may remove deposits that are gumming it up enough to give you intermittent problems.

If that doesn't do it, plan to remove the carbs and go through them.

[Triple Jim]

On the 250, moving the lever toward you turns on the enrichers ("chokes").

If the carbs were cleaned and the problem was fixed, and now it's back, I'd think it's possible that dirt is getting into the carbs from the tank. If you don't have a little plastic filter with a pleated paper element in the line from the tank to the carbs, adding one might prevent future trouble. Once you fix your current trouble, that is.

Don't use a sintered metal type filter. I've had them let enough dirt through to clog a jet.

[jschnetter]

Thank you all so much for the quick reply. I haven't been running it with the choke on, however it gets cold where I live. I think the bike might need to be warmed up more because it doesn't seem to happen when the engine gets all warmed up. There shouldn't be anything contaminating my carbs because they were pretty clean when they were cleaned a couple days ago and my mechanic went through a lot and cleaned stuff out.

[jkv45]

Originally Posted by jschnetter

Thank you all so much for the quick reply. I haven't been running it with the choke on, however it gets cold where I live. I think the bike might need to be warmed up more because it doesn't seem to happen when the engine gets all warmed up. There shouldn't be anything contaminating my carbs because they were pretty clean when they were cleaned a couple days ago and my mechanic went through a lot and cleaned stuff out.

That would suggest a lean mixture.

When the carbs were off, the caps on the idle mixture screws should have (hopefully) been removed (http://faq.ninja250.org/wiki/Removin...re_screw_plugs) . That's pretty much required to do a complete cleaning of the idle circuit because you need to remove the screws to clean the passages.

With the caps removed you can make adjustments to the idle mixture (http://faq.ninja250.org/wiki/How_do_...dle_mixture%3F) . A good base setting is 2.5 turns out. The stock setting in less than that, and gives a lean mixture, mostly for emissions reasons. Adjusting it closer to the correct mixture will get you a better idle, smoother transition from idle when you open the throttle, and better overall running - especially before you are up to full operating temp.

I'd check to see if the caps are off, and then carefully turn the adjustment screws until they bottom to see where they are set (which should be near 2.5 turns out). As temps drop you may need to make adjustments, as cold air leans the mixture and requires more fuel (turning the screws out) to get the correct ratio.

After you get the mixture adjusted properly, set the idle speed to the recommended setting of about 1300.

[Motofool]

I agree with Jay's comments above.
For cold conditions, your mix has much air and insufficient fuel.
When the engine is hot, less mass of air is entering into it, and combustion improves.
I suggest also checking the correct setting of the air filter, the fuel filters and the integrity of the vacuum hoses and rubber diaphragms.