Carb Synch Issue?

[ThatDude3K]

I recently bought an '06 250 Streetfighter that needed the carbs rebuilt (according to the owner). The bike would run with and without the choke but would die with the slightest amount of throttle. I rebuilt the carbs and the bike ran, throttled, and accelerated fine. However the rpms at idle would bounce between 800-1600. The internet led me to believe the carbs needed to be synced. I made a balance out of vinyl tubes and corona bottles (ayy) and synced the cards to the point that the water was even and not moving at all.. or atleast moving so slowly it was negligible. However the rpms still bounced between 1000-1200.

My question is are there any other things to worry about that could cause this issue?

I also got the bike with a vapor electric dash installed.. Is it possible that it was installed incorrectly or is so sensitive that it reads a varying numerical value when the oem analog dash would be stable?

And last but not least, if I rode the bike like this would anything get damaged? The bike accelerates shifts up and down smoothly without back firing.

[Z1R rider]

Sounds to me like the idle circuits still need cleaning (jets and passages in the carbs) and or adjusting. Did you have the idle adjusting needles out? If so, is it possible you lost the O-rings or washers in there? Or the O-rings may be bad. Or, is the engine actually changing speed or just the tach going crazy?

and welcome to the board!

[ThatDude3K]

Originally Posted by Z1R rider

Sounds to me like the idle circuits still need cleaning (jets and passages in the carbs) and or adjusting. Did you have the idle adjusting needles out? If so, is it possible you lost the O-rings or washers in there? Or the O-rings may be bad.

and welcome to the board!

I took both jets out of each carb and they were completely clear. Cleaner sprayed out of every hole on the jets. Cleaner would come out of the holes by the butterflys when I sprayed into the jet holes. I did not take the idle mixture screws out, they still had the EPA caps on them. I drilled out the caps just to look in there and everything looked clean so I didnt mess with them (the rest of the carb was bone clean when I took it apart and required almost no cleaning, all I did was replace the the squareish gaskets on the covers and the float bowl plugs). However I didnt take out or even turn the idle mixture screws.

[ThatDude3K]

Granted this is my first bike and don't exactly know what to look for or what to listen for. But the idle.. to my ear.. sounds stable and when I rev the bike in neutral it drops back down relatively quick. Just, like i said, the vapor tachometer will have fluctuating numbers. And if i ride the bike for a little bit, when I stop, the idles will be different from what I had set it to before I took off. For example.. If i adjusted it to the 1000-1200 range when I stop at a stop light down the road it will be 2500-3800ish. Maybe the bike wasnt all the way warmed up? Not sure.

And thank you for the acceptance!

[Z1R rider]

It sounds like you have to have the idle speed adjuster (black knob under left carb) has to be turned open (in) too far when the engine is cold or cool to stay running, then as the engine warms to operating temp. it idles to fast. A sure sign that at least one of the carbs still has a plugged idle circuit.

[ThatDude3K]

Originally Posted by Z1R rider

It sounds like you have to have the idle speed adjuster (black knob under left carb) has to be turned open (in) too far when the engine is cold or cool to stay running, then as the engine warms to operating temp. it idles to fast. A sure sign that at least one of the carbs still has a plugged idle circuit.

And what exactly do you mean by 'idle circuit'? Do you mean one of the passage ways that the jets are screwed into or the hole accessible from the outside where the mixture screws are?
I appreciate the help btw

[Triple Jim]

Are the valves adjusted correctly?

[ThatDude3K]

Originally Posted by Triple Jim

Are the valves adjusted correctly?

I'm not sure. But the bike has around 3500 miles on it. Unless I'm mis-
remembering the manual said the valves need to be adjusted every 6000 miles. Figured I didnt need to worry about that.

[ThatDude3K]

Also one of my original questions is still lingering.. Can I still ride it without damaging anything? (Until I have the cash to possibly take it to a shop and let them deal with it)

[Z1R rider]

Originally Posted by ThatDude3K

And what exactly do you mean by 'idle circuit'? Do you mean one of the passage ways that the jets are screwed into or the hole accessible from the outside where the mixture screws are?
I appreciate the help btw

The idle circuit includes all the passaged from the idle jet to the hole (slot) under the butterfly valve in the carb throat. The normal mixture screw starting point is 2.5 turns out from fully seated if the exhaust and airbox are stock, then fine tune from there. We've all kinda skirted the "is it safe to ride?" question because it's really hard to say without figuring out what the problem is. If it's real lean for some reason it could damage the engine.

If you can get carb cleaner to spray through the passages, and it appears you can, try running a couple of tanks of fuel with "Sea Foam" added, it helps clean out the small passages in the carbs. #1 son's 250 was running, and ran well at full throttle, but a little ragged at idle and small throttle openings, a dose of Sea Foam and he reported it runs like new again.

[ducatiman]

Sometimes chemical additives will work....note they require some degree of a "pathway" to wash tiny passageway surfaces. Precisely why sometimes additives work....sometimes not. Certainly worth a shot.

[ThatDude3K]

Originally Posted by Z1R rider

The idle circuit includes all the passaged from the idle jet to the hole (slot) under the butterfly valve in the carb throat. The normal mixture screw starting point is 2.5 turns out from fully seated if the exhaust and airbox are stock, then fine tune from there. We've all kinda skirted the "is it safe to ride?" question because it's really hard to say without figuring out what the problem is. If it's real lean for some reason it could damage the engine.


If you can get carb cleaner to spray through the passages, and it appears you can, try running a couple of tanks of fuel with "Sea Foam" added, it helps clean out the small passages in the carbs. #1 son's 250 was running, and ran well at full throttle, but a little ragged at idle and small throttle openings, a dose of Sea Foam and he reported it runs like new again.

Just slightly confused that the first paragraph said it might not be safe for the bike to ride, but to run a couple tanks with seafoam through.. Theres definitely not enough time in the world to idle a couple tanks lol nor does that sound like a solid idea anyway.

Also by ragged at small throttle openings.. When I go from closed throttle and open it there will be almost like a click or surge of power rather than a smooth coming on of power like when you press the gas in a car.

[ThatDude3K]

But I do think it could be beneficial to ride a tank or two through and see what happens. I have a feeling that the issue is something small and I also have confidence that everything is very clean.. Aside from maybe the idle mixture screws which as I said I didnt mess with.. If the seafoam doesn work I will pull them out and makesure the orings and all that are intact.

[ducatiman]

Thatdude...
You also wrote:

"The bike accelerates shifts up and down smoothly without back firing."

followed by this (later in the thread ....)

"When I go from closed throttle and open it there will be almost like a click or surge of power rather than a smooth coming on of power like when you press the gas in a car."

Sure sounds like pilot circuit(s) plugged, then transitions to midrange (a different circuit) which is clear and abruptly kicking in.

If you truly want to cut to the chase here....consider my services (PM me if interested) pull your carbs out...then check the valves while carbs being done.

If you are able and willing to do some labor, it'll be considerably less $ than a dealer....much quicker too.

[Z1R rider]

Originally Posted by ThatDude3K

Just slightly confused that the first paragraph said it might not be safe for the bike to ride, but to run a couple tanks with seafoam through.. Theres definitely not enough time in the world to idle a couple tanks lol nor does that sound like a solid idea anyway.

Also by ragged at small throttle openings.. When I go from closed throttle and open it there will be almost like a click or surge of power rather than a smooth coming on of power like when you press the gas in a car.

If it's running alright at anything off idle, drive it enough to run a tank or two of gas through it. If the transition from the idle circuit to the midrange circuit(needle that hangs down from the slide) is abrupt that is a sure sign that the idle circuit is not open. And you probably have to "sneak up" onto the midrange with very small throttle openings to get it to accelerate without a huge stumble.

I would strongly consider Ducatiman's services.

[ThatDude3K]

Originally Posted by ducatiman

Thatdude...

If you truly want to cut to the chase here....consider my services (PM me if interested) pull your carbs out...then check the valves while carbs being done.

If you are able and willing to do some labor, it'll be considerably less $ than a dealer....much quicker too.

Originally Posted by Z1R rider

If it's running alright at anything off idle, drive it enough to run a tank or two of gas through it. If the transition from the idle circuit to the midrange circuit(needle that hangs down from the slide) is abrupt that is a sure sign that the idle circuit is not open. And you probably have to "sneak up" onto the midrange with very small throttle openings to get it to accelerate without a huge stumble.

I would strongly consider Ducatiman's services.

Thank you guys. Im trying my best to put what Im experiencing into the correct words and I might be slightly off target with my word choice especially since as I mentioned 3 weeks ago I did not know a single thing about motorcycles. I will definitely try the seafoam today while the weathers nice.. I see a can at Advanced for $7 so I wont be losing much if it doesn't work.

@ducatiman I see your in NY.. How for are you from the Rockaway NJ Mall area?

[ThatDude3K]

Seafoam question though..

https://shop.advanceautoparts.com/p/...chTerm=seafoam

I just pour the bottle straight into the gas tank? Empty tank, half full, full?

[Triple Jim]

Not to be overly cynical, but I predict that Seafoam will not help because it's just oil, naphtha (not much different from gasoline) and isopropyl alcohol.

http://www.sueschauls.com/Seafoam_motor_treatment.pdf

If I had to try a fuel additive, I'd probably get a bottle of Techron. At least that's known to dissolve deposits in fuel systems to some extent.

[ducatiman]

Originally Posted by ThatDude3K

@ducatiman I see your in NY.. How for are you from the Rockaway NJ Mall area?

I'll send a PM with info on location

I'd agree Techron the preferable choice. Not even a full bottle (overdose) , maybe 1/2 to a full tank of FRESH fuel.

after 100 miles or so re-evaluate.

[Ram Jet]

Originally Posted by ThatDude3K

I took both jets out of each carb and they were completely clear. Cleaner sprayed out of every hole on the jets. Cleaner would come out of the holes by the butterflys when I sprayed into the jet holes. I did not take the idle mixture screws out, they still had the EPA caps on them. I drilled out the caps just to look in there and everything looked clean so I didnt mess with them (the rest of the carb was bone clean when I took it apart and required almost no cleaning, all I did was replace the the squareish gaskets on the covers and the float bowl plugs). However I didn't take out or even turn the idle mixture screws.

I pulled the E.P.A. plugs on my carbs last month. The factory had the mixture screw set a ZERO turns out on the left carb and 1.5 turns out on the right. At 2.5 turns off the seats the bike idles at a steady 1,000 R.P.M and I'm going to try for 800.

Just sayin'.

Bill

[Triple Jim]

Originally Posted by Ram Jet

...the bike idles at a steady 1,000 R.P.M and I'm going to try for 800..

You're pushing your luck.

[Ram Jet]

Originally Posted by ducatiman

Sometimes chemical additives will work....note they require some degree of a "pathway" to wash tiny passageway surfaces. Precisely why sometimes additives work....sometimes not. Certainly worth a shot.

I've been using this stuff "Techron" made by Chevron. I usually don't believe in magic elixirs for fuel additives but a fella I have a-lot of respect for when it comes to motorcycle mechanics swears by it. I'll have to admit that it smoothed-out the idle on my car. I put about 1/3 of a bottle in my 250 after completely draining my gas tank and then filled her up. I don't have any long term experience with the stuff though.

Bill

[Ram Jet]

Originally Posted by Triple Jim

You're pushing your luck.

Concerned about oil pressure? In about a week or so I'll know for sure what the oil pressure is at idle as I'm installing a mechanical oil pressure gauge.

Bill

[Triple Jim]

No, I just think that's pretty slow for that little engine.

I suggested Techron a few posts up.

[ThatDude3K]

Originally Posted by Ram Jet

I pulled the E.P.A. plugs on my carbs last month. The factory had the mixture screw set a ZERO turns out on the left carb and 1.5 turns out on the right. At 2.5 turns off the seats the bike idles at a steady 1,000 R.P.M and I'm going to try for 800.

Just sayin'.

Bill

But was slightly wonky and jumpy before hand lol?

[Ram Jet]

Originally Posted by ThatDude3K

But was slightly wonky and jumpy before hand lol?

Oddly enough the bike ran fine. It ran that way for 10 years. Go figure. I did note that when I got the carbs off I could see the point of the adjusting screw sticking up into the venturi on the left carb and just a hole on the right carb. I only drove the bike about 15 miles before going through it, adjusting the valves, 15 tooth countershaft sprocket, 105 to a 110 main jet, and Yoshimura slip-ons. It ran well before and beautifully now.

Bill

[Kestrel]

If you can pull the carbs out, you can certainly clean them; there isn't any magic involved, contrary to what some forum members here might have you believe.

Great walkthroughs available in the Ninja 250 FAQ over at Ninja250.org.

[ducatiman]

Originally Posted by Kestrel

If you can pull the carbs out, you can certainly clean them; there isn't any magic involved, contrary to what some forum members here might have you believe.

Owners access to appropriate workplace, proper equipment, his mechanical abilities, complexity of the carb issue, his application of methods within the carbs inner subsystems..... individual, differing scenarios of carb disrepair.... all contribute to negate such a blanket statement as above.

"Carbs are easy"......surely doesn't apply to all, certainly confirmed by the familiar posts we've all read...."I've cleaned them *X* times already!"

Poking the pilot jets is one thing...fully refurbing a 20 something year old set of carbs is another.

[Ghostt]

If it was that, easy, then why are there endless and endless threads about having issues with, and after carb cleaning.

At some point you need not only the proper tools, equipment, but the knowledge to do the work needed properly.

The services that Ducatiman offers he does for the love of the work, and services he provides to not only this forum, but others as well, and his prices for the services he offers are far cheaper that you'll find anywhere else.

He's the only one I trust with my carbs, which says a lot. Yes I can do my own, but he has invested the money in equipment, which isn't cheap by any means, saving me that expense.

[Kestrel]

Originally Posted by ducatiman

Owners access to appropriate workplace, proper equipment, his mechanical abilities, complexity of the carb issue, his application of methods within the carbs inner subsystems..... individual, differing scenarios of carb disrepair.... all contribute to negate such a blanket statement as above.

"Carbs are easy"......surely doesn't apply to all, certainly confirmed by the familiar posts we've all read...."I've cleaned them *X* times already!"

Poking the pilot jets is one thing...fully refurbing a 20 something year old set of carbs is another.

All of your first paragraph only serves to cast doubt and unnecessary difficulty on the act of cleaning a carburetor, thus increasing the likelihood of somebody paying to have it done rather than attempting to do it themselves. It's not rocket science; carburetors have been in use for well over one hundred years on everything from lawn mowers to aircraft engines.

If somebody wants to pay to have the service performed because they don't want to be bothered with the hassle of doing it themselves, that's certainly one thing. But it's another entirely if they're willing to learn and do it themselves, but are dissuaded by misinformation from vendors trying to peddle their services.

A CV carburetor is hardly complex. Let's not scare people away from trying to perform their own maintenance or learn more about the fueling process, when clearly the first few posts from the OP not only indicate decent mechanical ability, but a willingness to learn.

This bike doesn't need to be a black box.

[Triple Jim]

Originally Posted by ThatDude3K

Granted this is my first bike and don't exactly know what to look for or what to listen for. But the idle.. to my ear.. sounds stable and when I rev the bike in neutral it drops back down relatively quick. Just, like i said, the vapor tachometer will have fluctuating numbers.

Wait a minute! The engine sounds stable, but the tach shows a fluctuating speed? Electronic tachs are prone to electrical interference from the ignition system. Although not a sure thing, it's entirely possible that the problem is in the tachometer, not the carbs or something else.

And if i ride the bike for a little bit, when I stop, the idles will be different from what I had set it to before I took off. For example.. If i adjusted it to the 1000-1200 range when I stop at a stop light down the road it will be 2500-3800ish. Maybe the bike wasnt all the way warmed up?

It could be just that warming up caused the increased idle speed, so you shouldn't have adjusted it to 1,200 when it was cold. Also, back to the valves, mine did that when there was insufficient valve clearance to get them all the way closed when cold. Once I set the valves, it starts and idles well quickly, and the cold/hot idle difference is much less.

[ducatiman]

My first paragraph highlights the fact that people differ in their abilities and resources. I was also pointing out the nature of internal carb difficulties, and their repair paths, can differ wildly.

"Misinformation"? No, to the contrary...realistic.

Painting an illusion...generalizing, encouraging a kid of certain, first time success with no more in hand than a toothbrush and spray can while squatting in his outdoor, open apartment parking lot that "carbs are easy" is both unrealistic and irresponsible.

[Lazarus]

I did my carbs in an open apartment parking lot with some pinsol, carb cleaner, lots of beer, and a 48hr soak. the carbs, not myself. Point, is cleaning the carbs isn't hard but it also isn't easy. "Results may vary" encompasses it all.

[Kestrel]

Originally Posted by ducatiman

My first paragraph highlights the fact that people differ in their abilities and resources. I was also pointing out the nature of internal carb difficulties, and their repair paths, can differ wildly.

"Misinformation"? No, to the contrary...realistic.

Painting an illusion...generalizing, encouraging a kid of certain, first time success with no more in hand than a toothbrush and spray can while squatting in his outdoor, open apartment parking lot that "carbs are easy" is both unrealistic and irresponsible.

Sure, but a heated ultrasonic bath in a solvent isn't exactly magic/impressive/expensive, either. They're readily available on eBay, cost less than carb service, and would give folks a good tool for future use in any garage.

Forums exist for the spread of information. I don't like the idea of someone asking for carb help on a tech talk forum, and the immediate response from the collective consciousness to be 'give the carbs to this guy to clean', rather than actually helping the user troubleshooting the problem. Education is a wonderful thing. Each project has lessons to teach, and with each learning experience, we add to our knowledge base and skill set. As that skill set expands, so does our ability to tackle more complex issues, and further increase our knowledge. And next time you're stranded on the road, you might be able to experience a failure, diagnose it within 15 seconds of coherent thought, and pull apart your slide carb on the side of the road to find that the screw retaining the arm to the slide has backed out.... and after spending an hour fixing it, you're able to motor onward, rather than blinding calling a tow truck miles and miles from home. That is empowerment.

I say we're better served explaining the pilot circuit's operation, and the procedure for testing the passage to ensure adequate flow. Should the OP not be willing, or be unable to resolve that, then so be it - perhaps it's out of his ability to clean, and the ultrasonic bath might be just what it needs. That may eat into your profits from this forum, but I would argue that this forum doesn't (and shouldn't) serve merely as a medium by which we push posters toward vendors.

If they still can't figure it out, or simply don't want to handle, then sure... Suggest a vendor.

[ducatiman]

By all means, walk the walk....have at it...right here, right now....no one stopping you. Enlighten us all ...lead the OP to success.

[Ghostt]

Beyond common problems...... comprehensive carb cleaning is not for everyone, there is much to go wrong in short order. We've seen many members endlessly chase their tails, break stuff, assemble and adjust stuff wrong.

With some of the fleet becoming old, the vast majority require much more than "cleaning". The potential for leakage must be addressed, any less attention is irresponsible, and yes, this may even require thowing money and parts at them (gasp). Consumables...carb innards are not forever items.

And certainly there is MORE... much more....to it than simply addressing the pilot jets while they are out and on the bench.

Please...you're screwing around with FUEL...if not absolutely sure of what you're doing...send them to someone who is.

Also there is a huge difference between a cleaning, and a full refurbishment. Splitting, new O-rings on the rails, wet test, bench sync, etc.......

[jkv45]

Originally Posted by Kestrel

Sure, but a heated ultrasonic bath in a solvent isn't exactly magic/impressive/expensive, either. They're readily available on eBay, cost less than carb service, and would give folks a good tool for future use in any garage.

Forums exist for the spread of information. I don't like the idea of someone asking for carb help on a tech talk forum, and the immediate response from the collective consciousness to be 'give the carbs to this guy to clean', rather than actually helping the user troubleshooting the problem. Education is a wonderful thing. Each project has lessons to teach, and with each learning experience, we add to our knowledge base and skill set. As that skill set expands, so does our ability to tackle more complex issues, and further increase our knowledge. And next time you're stranded on the road, you might be able to experience a failure, diagnose it within 15 seconds of coherent thought, and pull apart your slide carb on the side of the road to find that the screw retaining the arm to the slide has backed out.... and after spending an hour fixing it, you're able to motor onward, rather than blinding calling a tow truck miles and miles from home. That is empowerment.

I say we're better served explaining the pilot circuit's operation, and the procedure for testing the passage to ensure adequate flow. Should the OP not be willing, or be unable to resolve that, then so be it - perhaps it's out of his ability to clean, and the ultrasonic bath might be just what it needs. That may eat into your profits from this forum, but I would argue that this forum doesn't (and shouldn't) serve merely as a medium by which we push posters toward vendors.

If they still can't figure it out, or simply don't want to handle, then sure... Suggest a vendor.

Most of the cheap-o ultrasonic cleaners are not adequate and aren't going to clean carbs that have obstructions.

If you haven't noticed, Ducatiman does chime-in a lot to help people that are struggling with their carbs - plenty of others do as well. Some times, no matter how much carb spray you use or how many wires you stick in the holes, you aren't going to remove an obstruction.

Many people just don't clean the carbs in enough detail, then struggle trying to get the bike to run. Some give up and take the bike to a dealer. The same type of service at a dealer would be significantly more and most likely not as well done.

The option of having them professionally cleaned and adjusted for a reasonable cost is a big plus for forum members.

Some people enjoy working on their cycles. Others don't and just want to ride.

[spent_too_much]

OK. I need to chime in...

From personal experience, I have watched videos, read through posts and instructions, and cleaned a half dozen Ninja 250 carb sets myself in the last year.

It isn't overly difficult, but not exactly easy either. I am mechanically inclined -
having torn apart and rebuilt three Pregens in the last year, methodical, and meticulous. And still, 50 % of the time I have had to remove, and repeat the process.

What I am learning, is that paying for experience, sometimes is the best way to go. I am on the fence about doing the next set myself, or having Ducatiman do them for me...

Just my 2 cents.

[Ram Jet]

Originally Posted by Kestrel

Sure, but a heated ultrasonic bath in a solvent isn't exactly magic/impressive/expensive, either. They're readily available on eBay, cost less than carb service, and would give folks a good tool for future use in any garage.

Forums exist for the spread of information. I don't like the idea of someone asking for carb help on a tech talk forum, and the immediate response from the collective consciousness to be 'give the carbs to this guy to clean', rather than actually helping the user troubleshooting the problem. Education is a wonderful thing. Each project has lessons to teach, and with each learning experience, we add to our knowledge base and skill set. As that skill set expands, so does our ability to tackle more complex issues, and further increase our knowledge. And next time you're stranded on the road, you might be able to experience a failure, diagnose it within 15 seconds of coherent thought, and pull apart your slide carb on the side of the road to find that the screw retaining the arm to the slide has backed out.... and after spending an hour fixing it, you're able to motor onward, rather than blinding calling a tow truck miles and miles from home. That is empowerment.

I say we're better served explaining the pilot circuit's operation, and the procedure for testing the passage to ensure adequate flow. Should the OP not be willing, or be unable to resolve that, then so be it - perhaps it's out of his ability to clean, and the ultrasonic bath might be just what it needs. That may eat into your profits from this forum, but I would argue that this forum doesn't (and shouldn't) serve merely as a medium by which we push posters toward vendors.

If they still can't figure it out, or simply don't want to handle, then sure... Suggest a vendor.

I have to plug Gordon just a-bit. He provides a quality service at a fair price. I for one am glad to know he's out there. I also respect what your saying about self reliance. I have never had any of my past eight motorcycles in anybody's shop for repairs but mine. I had a different childhood than most. My father was the consummate mechanic. He could tear down an Allison V-12 aircraft engine, a Wright Cyclone 9 cylinder radial engine and campaigned his own race car. I bought my first Craftsman complete tool set when I was 13. Today kids know nothing but TV and video games and if they're lucky have a straight blade screwdriver, a claw hammer and an adjustable open end wrench and hopefully a-lot of enthusiasm.

Well, you've gotta start somewhere but refurbishing complex Keihin CV carbs may not be a good place to start.

Cheers,

Bill

[ducatiman]

thanks for support, RJ and others.

Closely rereading the OP's floating RPM issues...I should have perceived a possible cause earlier.

The decel valve has 3 hoses above, 1 tiny one below (he stated he replaced that)

2 of these hoses route to vacuum barbs between the carbs and very well may be loose and leaking vac intermittently (varying cold to hot?) ....causing fluctuation in RPM's.

I've seen these hoses alarmingly loose on repeated occasions. They should be checked at all their points.

Tough to get to, extremely tight quarters between the carbs, but imperative that vacuum leaks must be checked and repaired if present. Much easier to replace hoses if carbs are split, allowing free access. Of course, if splitting its best to replace the fuel rail orings while you're there already...vent rail orings too.