2006 Ninja 250 Carb Problems

[Berathor]

This bike sat around outside for several months before I got to it and has always had a fuel starvation problem when moving at anything over 80mph. Originally, I thought the aftermarket inline fuel filter was causing it to starve. After replacing the fuel line it worked better but would still go into fuel starvation over 85mph.

Recently, it has started leaking fuel out of the carbs. After taking the carbs apart, I found that they were shiny clean. The floats rotate smoothly so I know I don't have a stuck open float valve. There's no scuffing or damage to the seal between the float bowl and the carburetor body. And as far as I can tell, there's no reason for the carbs to have been leaking. I put everything back together again and they're still leaking. It appears the leak is coming from the seal between the float bowl and the carbs. I'm going to go to my local dealer tomorrow to pick up new o-rings in case that's the problem.

Have any of you gurus encountered a problem like this? Even after I get new O-rings, and IF they seal up the carbs, I still don't know how to solve my fuel starvation problem. I've never owned or worked on a bike before this so I'm confused and more than a little out of my depth. Thanks!

[Ghostt]

I would first check the petcock for proper operation,

http://faq.ninja250.org/wiki/Rebuild...tcock/fuel_tap

After that just because the the insides are shiny, doesn't necessarily mean they are clean on the insides, jets, fuel circuits? Etc...

What is your level of experience with carburetors? The replace the O-rings on the fuel rail, you need to split the carburetors, which it a bit tricky.

I suggest you get your parts from @ducatiman he keeps a supply of parts on hand, and his prices are highly affordable, he also offers full services as well.

[sickopsycho]

Originally Posted by Berathor

This bike sat around outside for several months before I got to it and has always had a fuel starvation problem when moving at anything over 80mph. Originally, I thought the aftermarket inline fuel filter was causing it to starve. After replacing the fuel line it worked better but would still go into fuel starvation over 85mph.

Recently, it has started leaking fuel out of the carbs. After taking the carbs apart, I found that they were shiny clean. The floats rotate smoothly so I know I don't have a stuck open float valve. There's no scuffing or damage to the seal between the float bowl and the carburetor body. And as far as I can tell, there's no reason for the carbs to have been leaking. I put everything back together again and they're still leaking. It appears the leak is coming from the seal between the float bowl and the carbs. I'm going to go to my local dealer tomorrow to pick up new o-rings in case that's the problem.

Have any of you gurus encountered a problem like this? Even after I get new O-rings, and IF they seal up the carbs, I still don't know how to solve my fuel starvation problem. I've never owned or worked on a bike before this so I'm confused and more than a little out of my depth. Thanks!

@Ghostt knows what he's talking about- but do you have any mods on your bike? Aftermarket exhaust? Free-flow air filter? If it's fuel starved at high speed, does it not act fuel starved at lower speed but high rpm? What exactly is it doing to lead you to believe it's been fuel starved?
I am not a guru, but I recently had a similar problem where my bike was acting funky and I thought it was fuel starved. Turns out some monkey decided a paperclip would do the same as a c-clip on the dynajet needles he installed into the carbs. What was worse was he set them backwards- as in raised 1 side 2 notches over where it should be and lowered the other 2 notches from where it should be. so at low rpm and idle it was fine, but when I got on the gas it just acted very strange.
I would suggest going through the basics first. Obviously if your carb is leaking, that needs repairing. Could be that when you're WOFT it is leaking out and burning fuel faster than it can replace it (unlikely- that would be a big leak). Check your air filter- if its clogged up high rpms might not be moving enough air. Carb gaskets can be had online for dirt cheap. Even the el cheapo ones on amazon worked fine for me. The only issue I had was when I took the bowls back off, the gaskets would get wet with gas and swell. This might lead you to believe they'll never fit back in, but in reality all you have to do is set them out in the sun for a few minutes and they will dry out and shrink back down to size.
FTR, I bought a pair of Outlaw racing rebuild kits for our carbs. Part # is OR2728 and they can be had on Amazon for ~$32 for the pair. The kit comes with new float needles, new idle mixture adjust screws and the associated o-ring/washer/spring. It also has a bowl gasket- one of the el cheapo ones I mentioned. If there is any question about it, might as well rebuild this part. Also like Ghostt said pull the main jets and the pilots out and clean really well. you should be able to see through the jets, you can take a fine piece of copper wire to run through. I wouldnt use anything other than copper, as brass *might* be ok if you're gentle, but steel will scratch up the jets. A good cleaning of all the jets definately wont hurt- and might end up solving your issue. While you're there, you can check the float height and adjust accordingly. There is a wiki around here somewhere...
Actually you can refer to this thread to see how it's done.
https://www.ninjette.org/forums/showthread.php?t=279385

[Berathor]

Originally Posted by Berathor

Have any of you gurus encountered a problem like this? Even after I get new O-rings, and IF they seal up the carbs, I still don't know how to solve my fuel starvation problem. I've never owned or worked on a bike before this so I'm confused and more than a little out of my depth. Thanks!

As far as I know the bike is stock and has never been opened up or worked on in any significant fashion. All I've found was the inline fuel filter somebody added.

The O-rings that I'm talking about are the rectangular plastic seals that go between the float bowls and the carburetor body. I don't know what fuel rail you're talking about.

I'll take apart the jets today and double check that everything is in order. The carbs leak anytime the bike is running not just WOFT.
Yes, it only goes into fuel starvation when running in top gear about 9-10k rpm. Once it's been sitting at 9k for a few seconds, it begins to cough and splutter. If I don't roll off the throttle immediately, the engine will die and won't restart until after I'm stopped and have made several attempts at starting.

[sickopsycho]

Originally Posted by Berathor

As far as I know the bike is stock and has never been opened up or worked on in any significant fashion. All I've found was the inline fuel filter somebody added.

The O-rings that I'm talking about are the rectangular plastic seals that go between the float bowls and the carburetor body. I don't know what fuel rail you're talking about.

I'll take apart the jets today and double check that everything is in order. The carbs leak anytime the bike is running not just WOFT.
Yes, it only goes into fuel starvation when running in top gear about 9-10k rpm. Once it's been sitting at 9k for a few seconds, it begins to cough and splutter. If I don't roll off the throttle immediately, the engine will die and won't restart until after I'm stopped and have made several attempts at starting.

Yeah- the gasket between the bowl and the carbs is dirt cheap and easy to replace. The o-rings ghostt was talking about are in the fuel rail. They are also easy to replace in themselves, but when you take the 2 carbs apart you have to sync them back when you put them back together. The fuel rail is a small tube that connects the 2 carbs on the inlet side. You have a "L" shaped tube where your fuel line goes in, if you follow that tube you'll notice that it runs to both carbs. There are o-rings inside that tube where they join. You might want to look try to find out for sure that it's leaking from there before you unmarry the carbs, as like ghostt said it can be a little tricky to get them back correctly.
Good for you, though- removing the carbs can be a daunting task so if you got this far you may be fine going a little further. =) I love working on my bike for several reasons, not the least of which being if something gets messed up at least I'll know I did it. The money savings doesn't hurt, either. =)
Depending on how much it's leaking- that could be your problem. I just find it odd that you can run 9-10k in 3rd, 4th or 5th gear but only run into that issue in 6th.

[Mohawk]

You don't need another fuel filter. There is a muck trap gauze in the tank then a fine particle filter in the hose just before the carb feed elbow.

Check the orientation of the carb vent hose, it should be in a neutral or high pressure area, to maintain fuel flow. If its in a low pressure area, that will reduce fuel flow at speed.

Check the fuel level as well as my floats were at the correct height, but the fuel level was not !

[sickopsycho]

Originally Posted by Mohawk

You don't need another fuel filter. There is a muck trap gauze in the tank then a fine particle filter in the hose just before the carb feed elbow.

Check the orientation of the carb vent hose, it should be in a neutral or high pressure area, to maintain fuel flow. If its in a low pressure area, that will reduce fuel flow at speed.

Check the fuel level as well as my floats were at the correct height, but the fuel level was not !

If you replaced the fuel hose when you installed the filter, you may have thrown away the fine particle filter Mohawk was referring to- that happened to me.

@Mohawk- Can you explain what you meant by the orientation of the carb vent hose? Are you referring to the hose that runs up and connects to the rear of the gas tank? And what would a neutral or high pressure area be rather than a low pressure area?

Sorry to ask for clarification, but he said he doesn't know much about bikes and to be quite honest, I'm a little confused about this too- I'd like to know so I can check mine =)

[Ghostt]

Sidenote: PreGen doesn't have the small filter in the fuel inlet elbow, and the screens on the petcock only keep out large particles.

[sickopsycho]

Originally Posted by Ghostt

Sidenote: PreGen doesn't have the small filter in the fuel inlet elbow, and the screens on the petcock only keep out large particles.

Yeah- I put an inline in. It's one of the brass ones, so it moves more fuel but doesnt filter quite as well as a paper filter. My 2007 actually did have the filter in the fuel hose- it looked like a piece of gauze that somebody just stuffed in there. It was inside the fuel hose going from the petcock to the carb, and it was right before that black elbow.

[Mohawk]

Must have been a cost saving in USA they had the filter in the UK !

Between the carbs there is a vent hose that, that's what I'm referring too.

[Triple Jim]

Originally Posted by sickopsycho

Yeah- I put an inline in. It's one of the brass ones, so it moves more fuel but doesnt filter quite as well as a paper filter.

I've said it before, but I had a sintered metal filter let a chunk of dirt through that was big enough to get stuck in the main jet. I have zero faith in that type now.

[jkv45]

Originally Posted by Ghostt

Sidenote: PreGen doesn't have the small filter in the fuel inlet elbow, and the screens on the petcock only keep out large particles.

According to ninja250.org, Ninja 250s had them after 2000. I thought we had one in our 1990, but I could be mistaken.

[ducatiman]

i believe 49019-1085 inlet strainer (from a ZZR600) can be retrofitted to 250's with the black plastic fuel inlet

We've been adding them on EX500 carbs for years now, were supplied without from the factory!

I'll be doing a set of 250's this weekend, will confirm fit.

[Alex]

Is it up and running yet?

[Berathor]

Sorry for the late response.
I thought the gaskets in the carbs were fine because the seemed rubbery and pliable. After pulling them out it was obvious why they weren't working. They looked like they had melted, a good bit of the gasket stayed behind when I pulled em.
After a good cleaning and new gaskets, the thing runs much cleaner. No leaking gas, no fuel starvation, nothing. It's great. Thank you all very much for your help.

PS: Later I'd like to break open my engine block and return everything. A friend of mine with repair experience said that my engine top end sounds a little loose. Also, my dad who used to work for BMW says the same and that I should return it for my altitude. Exactly how much of a PITA is that gonna be?

[Triple Jim]

Originally Posted by Berathor

Sorry for the late response.
PS: Later I'd like to break open my engine block and return everything. A friend of mine with repair experience said that my engine top end sounds a little loose. Also, my dad who used to work for BMW says the same and that I should return it for my altitude. Exactly how much of a PITA is that gonna be?

I'm glad to hear you got things working better.

I don't know what you mean by breaking open your engine block. That would normally mean something like you plan to completely disassemble the engine and transmission, but I doubt if that's what you mean. You say "return everything", but maybe you mean re-tune? If you ride at high altitude, you can make some simple jetting changes in the carburetors to make up for the richness that the thin air causes. What are the symptoms you're noticing?

Maybe post a video of the top end sound you're referring to. It could be loose valve adjustment, bad cam chain tensioner, normal clutch noise, etc..

[jkv45]

Sounds like you might need a valve adjustment if it's making ticking noises from the top-end. Not necessary to "break open the engine block" unless you have serious problems with the transmission, crank, rod, or bearings.

I think you mean "re-tune" it for altitude. That involves mixture adjustments. Common adjustments are idle mixture (http://faq.ninja250.org/wiki/How_do_...dle_mixture%3F) and adding shims to the needles to richen the midrange if required.

Here's some how-to info on adjusting the valves - http://faq.ninja250.org/wiki/How_do_..._the_valves%3F

This is the main section with all sorts of info - http://faq.ninja250.org/wiki/Ninja250_Howto

[Triple Jim]

Originally Posted by jkv45

I think you mean "re-tune" it for altitude. That involves mixture adjustments. Common adjustments are idle mixture (http://faq.ninja250.org/wiki/How_do_...dle_mixture%3F) and adding shims to the needles to richen the midrange if required.

Broomfield, CO's altitude is over 5,000 ft. If he needs to change his mixture, I'd say he needs to drop the needles to correct his over-rich mixture, not raise them to make them richer. But since these 250 are very lean from the factory, he may not need to do much, if anything, to make it run right at 5,000 feet. A friend of mine had a 250 at around the same altitude in NM, and didn't find he had to make any jetting changes.

[jkv45]

Originally Posted by Triple Jim

Broomfield, CO's altitude is over 5,000 ft. If he needs to change his mixture, I'd say he needs to drop the needles to correct his over-rich mixture, not raise them to make them richer. But since these 250 are very lean from the factory, he may not need to do much, if anything, to make it run right at 5,000 feet. A friend of mine had a 250 at around the same altitude in NM, and didn't find he had to make any jetting changes.

True. That's why I added the "if required" part when I mentioned shimming the needles.

I really didn't understand exactly what the problem is or what he was told he needed to do, but thought the info may help.