I have a 2007 Ninja 250r; I wrecked it a few months back and the sparkplug blew out, threads got all burned out, I bought a parts bike and replaced the engine, the new engine is from a 1997 and I have no prior history on it.

Once the engine swap was done I took it for a test drive and it ran alright. Well the next day the bike would not run without choke, or if you BARELY twist the throttle it would simply die. So I pulled the carbs off, and took them apart cleaned them with a small piece of wire and reassambled them. Put them back on the bike and it ran alot better, but still was not right.

The engine seemed to starve for fuel between 5-9k rpm, and at a steady speed it would jerk and bog, also when you slowed down it would want to die. So whe I got home I noticed the airbox wasnt fully seated on the backs of the carbs, I loosened the bolts and pulled it forward and seated it properly, it did not seem to effect it.

The next thing I did was take my "Parts Carbs" and put them on, same effect, would not run when given throttle, nor would it run without choke.

I figured maybe it was the sparkplugs, I took them out to look for good spark. The left cylinder was getting good spark while the right was not. I replaced both with a good plug and when each had one the spark improved.

Well I lost daylight yesterday and I pulled the carbs and took them inside to clean as per instructions online, I pulled them all apart and boiled my jets and needles as well as checking diaphragms for rips and tears, checking float needle responsiveness, and that the float valve was operating properly. All things checked out, with CLEAN hands and clean tools and a clean work area I took my time reassembling the carbs. I want this to be the last time I have to do this for a while. I have put them in a plastic bag until I have timethis afternoon to put them back on.

My question to this forum is, what am I missing? I plan on picking up new plugs tonight, and cleaning the air filter element and cleaning all rubber boots that attach to the carbs, I also have fresh fuel, and an inline fuel filter.

Any and all prompt feedback is appreciated. I am BRAND NEW to this forum, but God help me if this community can help me solve my problem I have no problem making this my new home. :D

-Fuel is fresh
-In-Line fuel filter
-Clean Carbs
-Choke is not sticking
-Floats are not sticking

May need a carb sync?

do a compression check, just to determine the health of the new motor.

also, carefully check all vacuum hoses for leaks and where they connect for a tight fit and proper routing.

cali or 40 state model?

can you give us a cliff notes version of exactly what is wrong at this point? :)

Welcome James - you're in good hands here :)

I also have fresh fuel

To clarify...you already drained the fuel and added fresh or you're about to? How old was the fuel?

okay, I just put in the "clean" carbs, everything was clean, I also put in fresh spark plugs. The same thing is happening. This time it runs without choke at around 12-1500k rpm. It instantly dies when given gas.
With choke engaged it can be revved though it is a tad sluggish in accomplishing the task.

Fresh gas w2as added 3 days ago when I began the task of working on it. The old gas was approximately 4 weeks to over 1 month old. Also, I am aware of small rust spots in the tank, hence the inline fuel filter.

Would "Out of sync" carbs be to blame for such poor performance? If so, I am going to try the Yard stick and ATF fluid in a tube trick now.

EDIT: This is not the Cali model. All carb hoses are also routed correctly, these carbs worked fine on my last bike; sprayed the carbs (with Gum-Out Carb and Choke Cleaner) in all different places and no difference, vacuum leak is not probable in my opinion. Someone said this is not adequate for detecting leaks, should I try something more like Ether or Starting Fluid?

Did you put NOS in the gas tank? =P Sorry... Couldn't help myself.

Did you put NOS in the gas tank? =P Sorry... Couldn't help myself.

No I did not. I am however putting batteries in my camera to upload a video of the problem to better display the problem.

out of sync carbs would primarily affect idle, not when revved. it should not cause the symptoms you are seeing.

when you cleaned the carbs, did you remove the main jets and look through them to see if they were clean? same with the pilot jets? did you remove all parts form the carbs and blow compressed air through the passages?

remove the inline filter for now to make sure the bike is getting gas. speaking of filters, did you remove the stock filter at the entrance to the carbs? maybe it's blocked?

out of sync carbs would primarily affect idle, not when revved. it should not cause the symptoms you are seeing.

when you cleaned the carbs, did you remove the main jets and look through them to see if they were clean? same with the pilot jets? did you remove all parts form the carbs and blow compressed air through the passages?

remove the inline filter for now to make sure the bike is getting gas. speaking of filters, did you remove the stock filter at the entrance to the carbs? maybe it's blocked?

When I cleaned the carbs this last time I removed all needles and jets and boiled them in water for several minutes. Once that was done I removed them dried them, cleaned them again with carb cleaner, and visually inspected them as well as blowing them out with compressed air to ensure there were no obstructions. I did NOT however remove ALL hoses and blow compressed air through ALL holes. I was worried I would not be able to put the interior hoses back on. Was this a shortfall? Should I forgo the extra effort and do it anyway?

I did remove all stock fuel filters with the exception of those on the ends of the petcock tubes. The inline filter is 2 days old and there is adequate fuel flow to at least the bowls of the carbs.

The video I just made might be uploaded soon, or possibly later but it will be up by tonight. There are 2 videos, one of the carbs installed, showing all hoses are in their respective places, and another documenting the issues I run into when making it run. As well as some pictures.

Any other questions, simply ask, I am bound and determined to make this work without paying a $75/hr labor rate.

Any other questions, simply ask, I am bound and determined to make this work without paying a $75/hr labor rate.

good... cause I only charge $50/hr to help. :D

sounds like you have the carbs pretty much covered, but what interior hoses?

looking forward to the vids. :thumbup:

but what interior hoses?
Perhaps "interior" was a poor choice of word. The tubes that are on the Airbox side, between the two large openings recessed more towards the inside of the gap between the middle of the carb assembly. My fear is that after pulling them off it will be difficult to replace them.

I am back all, sorry I have been busy working on my truck. It now has a good Alternator, Air, and the Catalytic Converter is GONE! I have uploaded a video of my bike attempting to run.

g9xEuDH6szY

Clean your carbs. And buy an elbow for that gas line.

James,

for kicks, try removing the inline filter and have the gas run straight from the tank to the carbs, just to eliminate the filter as a problem.

also, try leaving the gas tank cap open and try starting the bike to see if that helps.

when you were inside the carbs, did you happen to check the float height level?

definitely acts like a fuel delivery problem, but I could be wrong. :o

did you clean the air filter? for now, try it without the air filter and see if that helps.

You might checking your valves. The valves on the new engine might be overly tight. Remember: "Flappy valves are happy valves." If you have the resources to do a valve adjustment, it might be worth a try. Everything else involved in feeding the engine has been covered it seems.

Did you reset the mixture screws? Sounds like you're running really lean.

Turn the 2 screws all the way in, then back them about about 2-2.25 turns and see from there.

if it will only run when fully choked, that means its starved for fuel, richen it up a bit and see what happens.

I have this problem when my bike is really cold. I start with the choke on, but when I give it gas, it dies. As soon as the bike is warmed up, it works like normal. My wife's bike does not have this problem. Maybe try getting the bike up to operating temp and see if it still does it?

Sorry for the SUPER long delay, but I have a full-time job since posting last and have had NO time to work on the bike, well I pulled the carb's back off for shits and giggles and while disassembling it I noticed that one of (forgive my non-technical terms) the black rubber "seals?" under the black plastic tops of the carbs was perforated just where the rubber goes into the seal, so I took one of the good ones from the parts bike and put it in its place. My question after asking that is, could that have been my problem? I only ask because I am waiting for the battery to charge back up and would like some fresh insight into this situation, also when I drained my tank there was a lot of debris in it, like rust, but I do have a solid in-line fuel filter in place since I don't have the extra $400 for a new tank, should I be good? Thanks guys you have been more than helpful thus far.

Sorry to bump my own thread, but I am in a little rush and don't want to edit, lol. But to update, today I replaced the part mentioned in the above post, and rigged together a test fuel can to both eliminate the fuel filter as an issue, and to be able to know there is no debris passing through, and wouldn't you know it, it runs. It runs, revs, and idles. I haven't had a chance to test ride yet, but wanted to update on the status. Again, thanks guys for being so much help!

Glad to hear there's at least progress!

sounds like you had a torn carb slide diaphragm. good job replacing and fixing the problem. :thumbup: