1986-2007 carbs

[juliusmichaelhonrada]

I really need a 1986-2007 carb, i have a 1988 ninja 250 japan domestic market i cant find someone who will ship a carb to me in the Philippines, i am willing to pay all shipping and duties its just that i cant find that part anywhere here 99% of the bikes here are 125cc mopeds

[Motofool]

Originally Posted by juliusmichaelhonrada

I really need a 1986-2007 carb, i have a 1988 ninja 250 japan domestic market........ bikes here are 125cc mopeds

Each carburetor of a Ninja 250 feeds one cylinder of 125 cc.
Any carburetor of a 125 cc moped should work if you can buy two that are similar (same moped model) or make a Y-shape manifold.

[juliusmichaelhonrada]

Originally Posted by Motofool

Each carburetor of a Ninja 250 feeds one cylinder of 125 cc.
Any carburetor of a 125 cc moped should work if you can buy two that are similar (same moped model) or make a Y-shape manifold.

I saw parallel twin bike here with 2 single carburetors , what they did was the throttle linkage is pulling another throttle linkage which makes a T shape the 2 end goes to each carburetor , and the fuel hose too .

But i think it wont work in the ninja because the petcock is Vacuum operated , and those carbs have no vacuum line inlet

[Motofool]

Originally Posted by juliusmichaelhonrada

........ But i think it wont work in the ninja because the petcock is Vacuum operated , and those carbs have no vacuum line inlet

Both things are a separate thing.

Vacuum operated petcocks stop fuel from spilling in an accident.

Constant velocity (CV) carburetors need a vacuum signal to properly wok, but not a slide type carburetor.

Any slide carb can perfectly work with a vacuum operated petcock.

Please, read about this here:
http://www.dansmc.com/mc_repaircourse.htm (60 to 78)

http://www.dansmc.com/cv_carb.htm

[juliusmichaelhonrada]

Originally Posted by Motofool

Both things are a separate thing.

Vacuum operated petcocks stop fuel from spilling in an accident.

Constant velocity (CV) carburetors need a vacuum signal to properly wok, but not a slide type carburetor.

Any slide carb can perfectly work with a vacuum operated petcock.

Please, read about this here:
http://www.dansmc.com/mc_repaircourse.htm (60 to 78)

http://www.dansmc.com/cv_carb.htm

Ok i have some knowledge about cv carbs , but where will i insert the vacuum line coming from the petcock to give it a vacuum signal?

[juliusmichaelhonrada]

I think i'll go into this route 1 carb -> 2 cylinder, can you help me sir on how can i make it to work , what carb size should i use , where do the vacuum inlet hose from the petcock goes now

[Motofool]

Originally Posted by juliusmichaelhonrada

I think i'll go into this route 1 carb -> 2 cylinder, can you help me sir on how can i make it to work , what carb size should i use , where do the vacuum inlet hose from the petcock goes now

Here you have an example:
https://www.ninjette.org/forums/showthread.php?t=267999

Anywhere in the manifold you can tap a nipple for the vacuum signal of the petcock.

[juliusmichaelhonrada]

Originally Posted by Motofool

Here you have an example:
https://www.ninjette.org/forums/showthread.php?t=267999

Anywhere in the manifold you can tap a nipple for the vacuum signal of the petcock.

thanks sir , is it possible that i can just replace the petcock from a 220cc bike with no vacuum line i think the flow will be big enough for the 250cc motor

[Motofool]

Originally Posted by juliusmichaelhonrada

thanks sir , is it possible that i can just replace the petcock from a 220cc bike with no vacuum line i think the flow will be big enough for the 250cc motor

Yes, as long as you can make the new petcock properly seal and bolt to the Ninja tank.

Are you sure that there is no shop in your place that could repair the original carburetors without being too expensive?

[RacinNinja]

The Kawasaki Eliminator uses the ZZR250 powerplant (possibly the EX250). There is no reason they shouldn't work if you take the time to fix them up. Are you sure all this custom work is worth it?

[juliusmichaelhonrada]

Originally Posted by RacinNinja

The Kawasaki Eliminator uses the ZZR250 powerplant (possibly the EX250). There is no reason they shouldn't work if you take the time to fix them up. Are you sure all this custom work is worth it?

yes sir , it would be alot cheaper , a 30mm keihin carb here cost only $15 for the 125cc mopeds and another $10 for the custom stainless intake manifold.

Even though the eliminator carb i have right now is complete and intact i am afraid it will cost more than $200 in repairs/shipping/import charges. The diaphragm alone will cost around $80 each

[juliusmichaelhonrada]

Ok guys , i got a 30mm OKO(KEIHIN PWK 28mm TAIWAN REPLICA) carburetor i got it for around 1000 pesos , or $23 bucks lol
The stock Main Jet is 138.
The stock Pilot Jet is 48.





Now im just waiting for the fabrication of the new intake manifold, while waiting can i ask you guys about the stock jettings of the Pre gen ninja , it will be a good starting point when tuning the bike

[RacinNinja]

Eh, not really. You're going from TWO carbs to ONE carb. Jetting is an unknown.

[juliusmichaelhonrada]

Originally Posted by RacinNinja

Eh, not really. You're going from TWO carbs to ONE carb. Jetting is an unknown.

Why , i guess the carb only gives fuel to 1 cylinder at a time so it must be the same? correct me if im wrong

[RacinNinja]

Without getting into intake and engine building theory, no, that's not how it works. You need to jet up from factory. Factory will be lean. If one 30mm carb was the way to go, Kawasaki would have done it at the factory to save expense and complexity. In other engines, tuners have had to go up as many as 14 main jet sizes from stock when going to a single carb.

You're going to lose some HP and move the peak power down in the RPM range, probably somewhere between 8-10K RPM. Simple fact is two carbs breath better than one because they aren't sharing and fighting intake pulses. There is a reason the other person here that did it says it turned the Ninja into a torque monster.....

If you tuned the intake length properly, though, you could minimize this effect. Might be a calculator you can find somewhere and enter the cam specs to get an idea of intake length. The smoother the split in the manifold, the better the high RPM power. A plenum would help solve the issue also as it would create a "reserve" of air/fuel for the engine to pull from.

But, the camshaft in the Ninja is designed for two carbs, so valve overlap, etc wasn't a concern. With a single carb, they will be fighting for air and fuel at higher RPM's which is why it runs good down low with a single carb.

Jetting database below. Good luck!

https://www.ninjette.org/forums/show...tting+database

[juliusmichaelhonrada]

I just need it to go and actually run and become useable , for now its a cheap and a simple economical solution until i get a proper carburetor.

I saw a honda goldwing 4 cylinders with 1 carburetor and it worked fine , i guess because its RPM limit is lower and it makes most of its power down in the Low End which single carburetors are good for.

That alternating pulses are also my concern(Intake on cyl.1 ,close. air/fuel charge has nowhere to go instead it tries to go out of the carb and cancel the vacuum of the incoming intake on cyl.2) and im aware of but by using a U manifold instead of a Y , hopefully i can reduce it and place the carburetor in the middle of the U exactly.

I had seen videos and dynos , the power that had been lost is not that much and i dont think i'll be revving up to 14k all the time (max traffic speed here is 80kph most of the time)

[Motofool]

Originally Posted by juliusmichaelhonrada

.............

Now im just waiting for the fabrication of the new intake manifold, while waiting can i ask you guys about the stock jettings of the Pre gen ninja , it will be a good starting point when tuning the bike

http://faq.ninja250.org/wiki/I_want_...uretor_jetting

[juliusmichaelhonrada]

Some progress , but i havent been able to make the U manifold , seems like people here are not skilled enough , rather i got this crude manifold rough but i guess it would work not the best though...

I cant seem to fabricate a perfect manifold without throwing some huge money.





Now the battery needs to be recharged and a nipple for the vacuum line on the gas tank petcock , then i will fire it up and see what happens


Is it normal that the battery heats up that much when cranking 7+ times , the positive - negative terminals seems very hot to the touch , then the battery wont work , wait a moment to cool it down and it works again..

The battery is brand new and was bought in 2010 , it was never used that much except for cranking before the bike was abandoned by the previous owner thats what he said

[Motofool]

Originally Posted by juliusmichaelhonrada

Some progress............

Is it normal that the battery heats up that much when cranking 7+ times..........

That is a good beginning, but is not the inlet too small for the carburetor outlet?
Do not tap the rubber boots; tap the Y manifold.

Do you have an air filter for the carb's inlet?
That will reduce noise and rain ingestion and cylinder wear.

Yes, the battery is only good for 4 or 5 tries:

http://faq.ninja250.org/wiki/Battery_stuff

Could you use a car's battery for the tests?

[crazymadbastard]

If you are going to run that chinese carb,it seems you mean is for a 125c moped. So you need 2 of those not just one. So basically a bolt on to the stock ninja carb intake boots.

Also would need something like this for the throttle cable:
http://www.speedmotoco.com/2-1-honda...-p/029-331.htm

another option may be an ex500 single carb into a similar manifold you have.

[juliusmichaelhonrada]

Originally Posted by Motofool

That is a good beginning, but is not the inlet too small for the carburetor outlet?
Do not tap the rubber boots; tap the Y manifold.

Do you have an air filter for the carb's inlet?
That will reduce noise and rain ingestion and cylinder wear.

Yes, the battery is only good for 4 or 5 tries:

http://faq.ninja250.org/wiki/Battery_stuff

Could you use a car's battery for the tests?

actually there is a small blank in the engine side of the oko carb , seems like it was there for a vacuum nipple installation

[juliusmichaelhonrada]

Originally Posted by Motofool

That is a good beginning, but is not the inlet too small for the carburetor outlet?
Do not tap the rubber boots; tap the Y manifold.

Do you have an air filter for the carb's inlet?
That will reduce noise and rain ingestion and cylinder wear.

Yes, the battery is only good for 4 or 5 tries:

http://faq.ninja250.org/wiki/Battery_stuff

Could you use a car's battery for the tests?

While i was tinkering around the bike , i noticed that the rectifier is not stock anymore , it has 2 bolts going through the rear fender right? ,i noticed that it wont line up , when i looked at the back of the Rectifier it says KYMCO(taiwanese scooter brands), what will be the effect that i should expect from this ? i mean is it significant enough that i should buy a stock ninja 250 rectifier

[Motofool]

All rectifiers do the same.
Can you take a picture?

[juliusmichaelhonrada]

Originally Posted by Motofool

All rectifiers do the same.
Can you take a picture?

I will try to take a picture tomorrow , i have news bro , so i got the barb nipple in place , and i got everything in place .

I had a problem at first the fuel wont go to the carb bowl, i found the culprit it was the float height , i twisted that metal a bit to raise it up fuel flows now but not that much(when i put a hose in the fuel inlet in the carb and try to blow it with my mouth there is a resistance).

I sucked that vacuum hose with my mouth so the fuel will flood the bowl, then i tried starting the bike, 1st try no throttle ,no choke = nothing just starter motor sound, 2nd try no throttle, full choke = engine started sputtering.

I tried cranking it 3 more times using the no throttle, full choke method it almost started but the battery died( i havent recharge it since i told you guys that i will lol sorry im so lazy) .

The reason why i dont have a throttle cable in the carb now is i dont know how to put it inside the carb... its a bit scary that a cable actually pulls the slide up (D-Slide PWK) so i decided to stop and check the internet for more information.

My air screw is all the way in bottomed out
My idle screw is quite bottomed out (spring resistance cant crank anymore with finger tight clockwise)

Im not sure how the idle screw ,its just a screw that goes through the back of the slide? but its the cable who actually pulls the slide up?

About the air screw i know that clockwise will make it richer and counterclockwise is lean.

Because the motor will sputter only with the choke fully on , my current mixture is lean ?

[FrugalNinja250]

You need some basic information, your experience and knowledge of fuel and air mixing in carburetors is severely impaired.

The way a carb works is that it has a narrow area where the air goes through. According to Bernoulli's principle https://en.wikipedia.org/wiki/Bernoulli's_principle when you have the same amount of air going through a restriction the air speed increases while at the same time the pressure decreases. This creates a vacuum. That vacuum sucks fuel from the carb bowl through a series of air mixing jets and tubes, atomizing the fuel and mixing it with the air stream so that when it arrives in the cylinder it is mixed at the right ratio to get maximum combustion and heat. This is called stochiometric and with gasoline it's about 14.7 parts air to 1 part gasoline. If you have more or less fuel for the amount of air then it's rich or lean, either way the amount of fuel burned is decreased as is the power and efficiency. https://en.wikipedia.org/wiki/Air%E2%80%93fuel_ratio

In car carburetors the air flow restriction, or venturi, is always the same size. This means that as you open and close the throttle the speed of the air flowing through the venturi varies dramatically, and that variation also dramatically affects vacuum. Since that vacuum draws fuel from the bowl, car carbureters normally have several different jets and metering circuits to ensure the proper amount of fuel for the air entering the motor at differing speeds.

Motorcycle carbureters are fundamentally different in that instead of having a fixed venturi and many fuel circuits and jets, they often have instead a variable-sized venturi and just one jet. The goal of the variable venturi carb is to keep the air speed through the venturi always the same, keeping the vacuum the same. These are referred to as CV carbs, for Constant Velocity.

The slides are the means of changing the venturi size, and they are operated by vacuum, not by the throttle cables. If the slide diaphragms are damaged then all sorts of problems occur.

I think you will end up spending far more trying to get this bike to work on one carb than you would saving up for a year (if needed) and buying a proper set of carbs for it. If you cannot (or refuse to) get factory carbs, look for a pair of carbs with the same size bores as the factory carbs, but you will need a lot of jet tuning since the amount of fuel for the air is related to horsepower output. IIRC the Ninja 250 is rated around 35HP at the crank, so looking for carbs from single cylinder motors rated at 17-18HP will get you in the ballpark. You'll also need to come up with a system to join and synchronize the carbs, etc.

[juliusmichaelhonrada]

Originally Posted by FrugalNinja250

You need some basic information, your experience and knowledge of fuel and air mixing in carburetors is severely impaired.

The way a carb works is that it has a narrow area where the air goes through. According to Bernoulli's principle https://en.wikipedia.org/wiki/Bernoulli's_principle when you have the same amount of air going through a restriction the air speed increases while at the same time the pressure decreases. This creates a vacuum. That vacuum sucks fuel from the carb bowl through a series of air mixing jets and tubes, atomizing the fuel and mixing it with the air stream so that when it arrives in the cylinder it is mixed at the right ratio to get maximum combustion and heat. This is called stochiometric and with gasoline it's about 14.7 parts air to 1 part gasoline. If you have more or less fuel for the amount of air then it's rich or lean, either way the amount of fuel burned is decreased as is the power and efficiency. https://en.wikipedia.org/wiki/Air%E2%80%93fuel_ratio

In car carburetors the air flow restriction, or venturi, is always the same size. This means that as you open and close the throttle the speed of the air flowing through the venturi varies dramatically, and that variation also dramatically affects vacuum. Since that vacuum draws fuel from the bowl, car carbureters normally have several different jets and metering circuits to ensure the proper amount of fuel for the air entering the motor at differing speeds.

Motorcycle carbureters are fundamentally different in that instead of having a fixed venturi and many fuel circuits and jets, they often have instead a variable-sized venturi and just one jet. The goal of the variable venturi carb is to keep the air speed through the venturi always the same, keeping the vacuum the same. These are referred to as CV carbs, for Constant Velocity.

The slides are the means of changing the venturi size, and they are operated by vacuum, not by the throttle cables. If the slide diaphragms are damaged then all sorts of problems occur.

I think you will end up spending far more trying to get this bike to work on one carb than you would saving up for a year (if needed) and buying a proper set of carbs for it. If you cannot (or refuse to) get factory carbs, look for a pair of carbs with the same size bores as the factory carbs, but you will need a lot of jet tuning since the amount of fuel for the air is related to horsepower output. IIRC the Ninja 250 is rated around 35HP at the crank, so looking for carbs from single cylinder motors rated at 17-18HP will get you in the ballpark. You'll also need to come up with a system to join and synchronize the carbs, etc.

Yes sir , i know all of that i was asking about the rpm screw on a flatslide carburetor , because i only know CV carburetors the screw modifies the position of the butterfly valve inside the throttle body. But in a flatslide carburetor it is different i guess it controls the amount of gas because the slide is actuated by the throttle cable directly.


I dont agree with you, 250cc is a very small displacement

Here is a 400cc with a single carb (40MM which he was oversized and later regretted and which he wants to go 32mm)
https://www.youtube.com/watch?v=Omu5aqvBa3M

If 32mm is optimal for a 400cc
I believe my 30mm will be more than optimal for my 250cc

Cars for example has more than one cylinder (inline 4 most of them) and they dont use a 4 barrel carburetor ,they use a single barrel 40mm carburetor that services displacements up to 1000cc-2000cc+

[Motofool]

Originally Posted by juliusmichaelhonrada

........The reason why i dont have a throttle cable in the carb now is i dont know how to put it inside the carb... its a bit scary that a cable actually pulls the slide up (D-Slide PWK) so i decided to stop and check the internet for more information.

My air screw is all the way in bottomed out
My idle screw is quite bottomed out (spring resistance cant crank anymore with finger tight clockwise)

Im not sure how the idle screw ,its just a screw that goes through the back of the slide? but its the cable who actually pulls the slide up?

About the air screw i know that clockwise will make it richer and counterclockwise is lean.

Because the motor will sputter only with the choke fully on , my current mixture is lean ?

The slide should have a recess into which the end/head of the cable goes.
No problem with that, as long as the slide is free to move up and down and to come all the way down by internal spring action.

The idle screws just limits how far down the slide can go.
As initial setting, you should see @ 2 mm gap between the bottom of the slide and the wall of the throat.

The mix can be lean for high rpm's if the level of fuel inside the bowl is too low.
See if you can find the level that is recommended by the manufacturer of the carburetor.

[juliusmichaelhonrada]

Originally Posted by Motofool

The slide should have a recess into which the end/head of the cable goes.
No problem with that, as long as the slide is free to move up and down and to come all the way down by internal spring action.

The idle screws just limits how far down the slide can go.
As initial setting, you should see @ 2 mm gap between the bottom of the slide and the wall of the throat.

The mix can be lean for high rpm's if the level of fuel inside the bowl is too low.
See if you can find the level that is recommended by the manufacturer of the carburetor.

Thank you again , i look at the slide while screwing the IDLE adjuster and i can see the slide going up

[juliusmichaelhonrada]

Update:

Got the battery charged .
Adjusted the float height(it was the inline fuel filter that actually restricts the flow of fuel , i tried blowing it with my mouth it has no resistance but somehow when i put it in air pockets form in the inline filter and the gas from the tank cant go down .

Good news
I got the bike running with the single carb it will only start (1 press of a button) with the choke fully on.

Problems :
1.It will only rev up to 8,000 RPM (I guess i need a bigger main jet) or a richer needle.

2. I need a bigger pilot jet
3. I have some leaks in the intake manifold i guess thats the reason why it wont idle without the choke on (same problem i saw in the honda steed forum).

I guess i have to ditch this manifold and find a real professional welder....

[Motofool]

Originally Posted by juliusmichaelhonrada

........3. I have some leaks in the intake manifold i guess thats the reason why it wont idle without the choke on (same problem i saw in the honda steed forum).

I guess i have to ditch this manifold and find a real professional welder....

Good progress !!!

An air filter will make the mix richer.
I would try riding the bike as is for some trips (away from traffic, if possible).
After that, the color of the spark plugs can tell you how good the mix is.

You could verify those suspected leaks by temporarily putting bearing's grease over the welds.

[juliusmichaelhonrada]

Originally Posted by Motofool

Good progress !!!

An air filter will make the mix richer.
I would try riding the bike as is for some trips (away from traffic, if possible).
After that, the color of the spark plugs can tell you how good the mix is.

You could verify those suspected leaks by temporarily putting bearing's grease over the welds.

The leaks are confirmed , when i touch the manifold its wet with fuel , just under the part where the stock intake boot and the welded manifold join , i guess the imperfection in the manifold some wrinkles and craters and its not smooth is the cause of the leak..

I would go tomorrow to a professional muffler shop and let them make me a full stainless steel manifold smooth , U shaped and professionally made..

The Spark plugs btw is old and its gap is like 1mm , because i have no feeler gauge that time i took a washer and measured with avenier caliper(around 1mm) and pushed it over the spark plugs , the Cylinder 1 spark plug has actually no gap when i first removed it , it creates a massive explosion in the muffler everytime i try to start it back then

[Motofool]

Originally Posted by juliusmichaelhonrada

..........The Spark plugs btw is old and its gap is like 1mm , because i have no feeler gauge that time i took a washer and measured with avenier caliper(around 1mm) and pushed it over the spark plugs , the Cylinder 1 spark plug has actually no gap when i first removed it , it creates a massive explosion in the muffler everytime i try to start it back then

Try adjusting both gaps to about 0.6 mm.

http://faq.ninja250.org/wiki/Changin...rands_to_avoid

.

[juliusmichaelhonrada]

I will , is it okay that i use a different spark plug , because the one in the factory manual will sure be hard to find here , can i just use another spark plug thats more accessible to me then gap it 0.6mm

[Motofool]

Yes, that gap should be the same for any brand of spark plug.
As the article of the previous link explains, try avoiding the Champion brand, unless it is of a colder grade.
Also, for any other brand available, try finding the same heat grade, more or less.

[juliusmichaelhonrada]

Originally Posted by Motofool

Yes, that gap should be the same for any brand of spark plug.
As the article of the previous link explains, try avoiding the Champion brand, unless it is of a colder grade.
Also, for any other brand available, try finding the same heat grade, more or less.

I found something horribly wrong , this is why it wont idle in the first place . After putting a new carburetor and all leaks resolved , now it shows the exact same symptoms with the 1st old carburetor (wont idle , needs to use choke to start).

As i open the cylinder head cover , and put the crankshaft on 2Top dead centre, I can see that the In mark on the intake camshaft is OFF by like 8 TEETHS! oh my god.

And same with the EXHAUST camshaft .

It should be facing the the cylinder head gasket horizontally right ?
I dont know how to adjust the timing chain can you help me good sir

[Motofool]

Originally Posted by juliusmichaelhonrada

I dont know how to adjust the timing chain can you help me good sir

Consider that there are two turns of the crankshaft for each turn of the camshafts.
For that reason, you will see misalignment of the marks in the cam sprockets for one position of the crankshaft at #2 piston TDC.

What year is your engine?
If pre 2008, read this:

https://www.ninjette.org/forums/showthread.php?t=147316

[RacinNinja]

Needing choke to start isn't a symptom....that's normal.

Rotate the crankshaft another 360 degrees and check the cam timing marks again. Like Motofool said, crankshaft rotates twice for every revolution of the cam shafts.

[juliusmichaelhonrada]

Originally Posted by Motofool

Consider that there are two turns of the crankshaft for each turn of the camshafts.
For that reason, you will see misalignment of the marks in the cam sprockets for one position of the crankshaft at #2 piston TDC.

What year is your engine?
If pre 2008, read this:

https://www.ninjette.org/forums/showthread.php?t=147316

that exact same thing happened to me , i already adjusted the in and ex mark facing the cylinder head surface and with 33 links visible , i found out the previous owner swapped the intake cam to the exhaust cam so i have to remove everything.

i double checked everything tried to turn the crank no loud bangs , all rocker arms in place , all have play , flywheel in 2T mark , IN/EX mark in head surface , but then it failed to start now , not even a Sputtering when turning the choke on , i checked the carb bowl if its getting fuel by removing the drain screw and lots of fuel came out , i dont wanna give up now but i feel so tired and sad but tomorrow i will double check everything .... i have this huge feeling that i messed up the timing because there is a serial number in the flywheel that looks like a 2T mark, Its actually 21 . and there is also a 2H mark , my cant see that much from the red oil thats covering the flywheel and the sun flaring up above me so my last shot tomorrow

[juliusmichaelhonrada]

i have read the thread , this Shear Slip on the flywheel i want to know more about this , because when i was turning the Flywheel counterclockwise , the Nut became loose and i have to turn clockwise to torque it down again , MAYBE the flywheel slipped and now my Spark Timing is way way out? and 2T mark is not really #2 Top Dead Center?

[juliusmichaelhonrada]

btw when i opened my cam chain tensioner , there was no spring inside , and its all rusty and dirty, there is just 1 bolt , and 1 round like bearing .. but still when i put the cap on , it still give some tension on the cam chain to the point that teeths dont jump