Moto carb trouble question

Howdy yall, just looking for more ideas, i'm basically out

I got a ninja 250. had it forever, 2006, around 18k. Always been super reliable.

Recently it stopped starting, traced the trouble to the airfilter (foam) having disintegrated and sucked all thru the carb and clogged a few small passages and whatever.

So I cleaned the shit outta the carb, then ultrasonic cleaned it, then cleaned it some more. While I had everything off I reset the valves too, 2 were kinda off, theyre all picture perfect now. New air filter, changed the oil too for poops and hahas

Now, I get it together and it idles like shit. It's either 4000 or like 500 and dying.

So I think, gotta be idle circuit, i played wide with the air/fuel screws, meticulously re-cleaned the idle circuit holes and stuff, (which holy fucking shit it sucks getting those carbs out, that's a full evening gone), bench sync'd and a/f adjusted to factory

but all reassembled, nothing's better. I'm kinda outta ideas, i havent checked for airleaks but i'm pretty certain there arent any cuz I cant imagine where there would be. but I really got no other ideas.

Has to be idle circuit. thansks for listening, typing this out has me thinkin i gotta 1st double check no airleaks but really just try again and see if theres any dumb small holes in the carb i mightve missed or some shit. god i hate getting those carbs out.

Re: Moto carb trouble question

Don't have one of these, but are there boots between the carbs and cyl's? They can degrade and have tiny holes allowing for air leaks.

Re: Moto carb trouble question

I fussed forever with a pair of carbs on my GS500.

Cleaned the carbs, lined the tank, cleaned the carbs again, rode for a week, acted up, cleaned the carbs.

I still have no idea why they got all shitty like that and it was so inconsistent.

Mine were mounted with boots and, if I remember correctly, had a diaphragm on top.

If I had to do it all over, I would have just spent the money on a dealer rebuild kit.

I feel your pain though.

Re: Moto carb trouble question

I had a 1996 and I had to clean the carbs one year after a long hibernation.

I am sure that you know some of this... but have to say to be sure.

On some of these bikes you need to remove a cover over one on the adjustments/jets do not remember very long time ago.

Have you done this area?

If your foam disintegrated... could there be anything blocking the intake tract?

Sitting thinking... reverse blow through all of the passages? I am sure you have done this too.

Yes the idle passages are very small. I feel for you. Time consuming job.

Re: Moto carb trouble question

Born to be WillD /

the covers are over the airfuel screws, they put lil welch plug covers over em so you couldnt mess with adjustments for emissions reasons, i yoinked those doodads out a long time ago. I am pretty familiar with those air fuel screws (it SUCKS to adjust cuz you gotta be warmed up and then you're either burning your hands to reach in there, or consistently fumbling a short mini screwdriver with dumb bulky gloves)

I'm gonna grab some thin wire and poke through some of the tiny holes that i previously only blew or sprayed out. gotta be somethin somewhere messing me up

Re: Moto carb trouble question

Probably Fred /

Is your compression good ?

if you sucked stuff through the carb that means you sucked stuff into the engine, you could’ve stuck up some rings and have cylinder score damage

Re: Moto carb trouble question

♣Slew Foot♣ /

Maybe it needs a slight restriction in the airbox like a backscavenging system.

Re: Moto carb trouble question

If you know about those cool. They are a pain in the butt.

Again if memory serves me right the Idle Jets are extremely tiny. I remember having a hard time finding a wire small enough to go through it. I had to use the smallest drill on my tiny drill index... But once cleared all was good.

Now I am curious as to how much of the air filter foam you sucked up? Did you suck up fine particles are big chunks? Could residue be under the Valve seats causing lower compression?

Good luck with this one.

FYI I had 2 of these in my life time. The very first was an 86 model maybe 87? Anyhow I installed a Kerker Full Exhaust system on it. The shop then tuned it for me. What a very fun bike that was.

Re: Moto carb trouble question

Born to be WillD /

It's a great bike, but i still havent got it, i have some very fine wire im going to poke out holes - I have some suspects.

the symptoms really feel like a carb problem

the filter bits was all pieces of foam mesh that probably got pretty well decimated if they made it in but it could be some debris and coke from them metling in the valves or whatever. woof.

i hope not

Re: Moto carb trouble question

> I'm gonna grab some thin wire and poke through some of the tiny holes

> that i previously only blew or sprayed out. gotta be somethin somewhere

> messing me up

Dude I think your on it. Those idle circuits suck. Do they have a “jet” that you can remove at the opening to where the air box mounts?


Such tiny passages. Also have you replaced the diaphragms? Sometimes the CV crabs act irratic if you do t replace them. I did some dumb bike for a guy that had one CV and one regular carb. He did not want to buy the carb kit and the second cylinder would idle like shit. It would hit and miss. I made him buy the kit and bam it was gone. Idk just throwing ideas out. I’m sure you will get it.

Re: Moto carb trouble question

I think it was a Suzuki Boulevard that was turned into some dumb chopper that I did not like…..not that it matters and has nothing to do with Wills problem, but it was dumb to have two different carbs from the factory. Sorry and thanks for listening to my rant. Ugh it was stupid….

Re: Moto carb trouble question

Not dumb at all, I would have never guessed a bike would come with 2 different carbs factory, there must have been some reason, though I can't imagine what it would be. It's always cool (to me anyway) to learn such things, you never know when it could come in handy!

Re: Moto carb trouble question

Born to be WillD /

yea i ordered some diaphragms

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