up jetting ninja 250 09

[erlas]

hi mates, I have a slip on ixil dual exhaust and im going for dual chrome air filter pods. I was wondering what size id need to upjet and if i have to upjet everything or just the main jets? thanks

[Ghostt]

Personally I wouldn't recommend pod filters, bad idea with CV carburetors, and jetting I'd go 2 washers on the main needles, and then maybe if needed one size on the main jets, don't forget to tune those pilot jets for best performance.

If needed I can explain further.

[erlas]

Originally Posted by Ghostt

Personally I wouldn't recommend pod filters, bad idea with CV carburetors, and jetting I'd go 2 washers on the main needles, and then maybe if needed one size on the main jets, don't forget to tune those pilot jets for best performance.

If needed I can explain further.

what do you mean 2 washers? Sorry gonna be my first time doing this as my friend said if i have aftermarket exhaut and filters thats a +3 upsize the main jet. Dont know about sizes at all what to get

[Ghostt]

Originally Posted by erlas

what do you mean 2 washers? Sorry gonna be my first time doing this as my friend said if i have aftermarket exhaut and filters thats a +3 upsize the main jet. Dont know about sizes at all what to get

I'm assuming the carburetors are in proper working order,

Okay first off your only adding new slip on right? Not a complete system? So going up 3 sizes is a little extreme, in any case, unless you have access to an exhaust gas analyzer.

Okay the washer modification is common for the Ninjette, you will need 1 or 2 4mm washers, and you use them them as shims under the metering needles part # 16009 , just slide them on before you install them. That will usually be enough without having to do anything else, maybe try another washer if necessary, but 4 should be the maximum if I remember correctly.
.

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



Now on to tuning the idle mixture screws, have you removed the caps yet? I'm not sure if the overseas market has them or not?

http://faq.ninja250.org/wiki/Removin...re_screw_plugs

Once you have access to the idle mixture screws, then follow my guide,

Your initial setting should be 3 full turns out from the bottom, remember just slightly tighten them, don't go all Conan on them.



Then warm it up, slowly turn 1 side pilot screw in until the rpms drop, then back out till RPM's peak (and no further)* Twist throttle...see how it reacts...tweak to taste.
Repeat on other side... test ride. You're looking for best throttle response and transition from just cracked to 1/4 throttle opening or so.*

Thats a quickie, 10 cent tutorial on setting pilot screws.**

If after all that it still feels lean, then go up 1 size on the main jet

Now on to why pod filters are a no no

I would highly recommend that you DO NOT REMOVE THE AIR BOX, the carburetors on the bike are CV type and need to box to function properly, buy a K&N that fits the OEM airbox(K&N KA-2508 Kawasaki High Performance Replacement Air Filter by K&N Amazon.com: K&N KA-2508 Kawasaki High Performance Replacement Air Filter: Automotive Amazon.com: K&N KA-2508 Kawasaki High Performance Replacement Air Filter: Automotive ) that's the short version.

Long boring but important answer, CV carbs stands for "constant velocity". The function of the carbs is dependent on having a calm reservoir (airbox) from which to intake air at said constant velocity. Pods draw from the turbulent, unpredictable air swirling past them as you ride, which is anything but constant. Other carbs work fine with pods. CV's = no bueno, save yourself the headaches.

Now onto jetting, first you need to tune the idle mixture screws first, I recommend 3 full turns out from bottom as a good starting point, then fine tune them afterwards. As far as buying a jet kit, I personally don't have one on either my 250, or 500 ninjas. I did got up one size on my main jets, due to they are lean from the factory, and shimmed the main needles with a small washer.

And finally before you ask about carburetor synchronization,

You can sync with the carbs in hand. Back the idle adjustment off to close that carb then match the second carb to it with the sync screw. You can then turn the idle adjustment up while using a thin feeler gauge (maybe .002") between the throttle plate and the throttle bore, adjust to just fit, and then check the second one and adjust to match. If you have good feel for this it will run fine once installed.

It would do folks well to take a minute to review and understand what a sync tool does, how it works. And take another minute to look at the carb linkage and sync adjustments available to fix irregularities that might occur. It can help take some of the mystery out of this as well as stop unnecessary carb sync screwups.

Meaning, that the carbs were right once, the butterflies were matched and it performed well, but then changed. Undecided And the problem somehow occurred in the butterfly direct shafts, or the sync screw turned or wore that pad that it rests on, or the carburetor pairing/ bridging brackets twisted in relation to each other, and enough so that the butterflies no longer operated in sync, such that performance noticeably suffered. And a fix will be accomplished by changing the butterfly position, the only thing the sync adjustment does. Hmmm. Really? Undecided

Meanwhile, the tool measures vacuum at each individual runner. That's all it does, how it works. And vacuum is effected by a huge list of things, butterfly position being only one of them, and the only one addressed with that tool while turning those sync screws. The rest of that list includes, valve adjustment, jetting, float level, compression differences between cylinders caused by wear as well as factory CC differences in the head, intake runner, as well as flow by port variations, etc. Variations in cams, wear or factory tolerance. Then there's the potential big one, pilot jets and pilot screw mixture settings. All of those effect the vacuum and will be read by the sync tool, accurately identifyng the difference that exists, and with the only adjustment being used to "correct" the problem, move the butterfly relationship, one to the next.

It's that clear understanding that has me of the opinion and long time practice to not touch the sync screws on a set of carbs that were right once and were never dismantled from the rack. And jet cleaning as well as float needle changing doesn't require that they be dismantled. And further, if I DID dismantle a set of carbs, I just matched the butterflies on the bench at assembly, using a feeler gauge, and then never touched them again, never gave them another thought.

That method, properly executed, will have THAT portion of the complete equation, balanced flow to each cylinder in a multi-cylinder/ carb application due to butterfly position, satisfied entirely adequately. And in fact, it has worked for me every time I've done it on every bike (as well as individual runner/ butterfly V-8 intakes, all eight) that I've ever owned or any that I've fixed for others. And the times I fixed for others was usually after an attempt by others to sync the carbs, chasing a problem, or sometimes not even chasing a problem, but one they created wth a sync tool, chasing a problem from that list, that was never a butterfly position change problem. Those linkages are so direct and simple that they don't know how to screw themselves up. Not enough to care about.

I'm sure this will start a lot of controversy so I won't argue it, just offering it for those who understand the whole picture that I outlined and might make good use of it. It is what I've done, on every engine I ever worked on, including blue printed racing engines as well as regular old, high mileage street stuff. I've had at least four, four cylinder bikes with over 100,000 miles that ran quite well, the whole time, and never had a carb sync performed. When they did finally get a total disassembly, this is how I set them up, on the bench. Over the years I've straightened out at least a half dozen messed up ones, probably more, and on the bench, after fixing the original problem which was fouled pilot jets.

I only posted this because it seems like its coming up fairly often, especially with problems from a sync gone bad. One I would suggest was never a sync problem to begin with. A big or sudden change in performance is NEVER a sync problem. NEVER. Remember that. Cool If there is a problem, and you connect the gauges? YES, there will definitely be an imbalance indicated. But because that hole has a problem that is from the rest of the list. A bad plug, a plugged pilot jet, a screwed up float, a bad valve or setting, etc. Every one of them effecting the vacuum in the intake but NOT from a sudden move of a butterfly position, a sync adjustment.

Hope this helps, if any more questions, just let me know.

[erlas]

thanks for that when all parts come and i have time off work ill get on to that. Just one question for now is do i need to take off carbs to put on couple more washers? as i read some guide that said i dont need to remove in order to change jets but not sure about needles. This is my first time working on a ninja 250

[Ghostt]

You can leave the carburetors installed and do the washer modification, but it's a little tricky. If you get something wrong, you'll be pulling the carburetors.

To be honest, once you get the hang of removing/installing carburetors, it's a lot easier to work on them off the bike, and on the bench.

Don't forget you have the adjust/tune the idle mixture screws too, per my guide above.

Raising the needles can actually be done without removing the carbs from the bike. Pull the tank, without pulling the upper fairing. You'll need a good-condition #2 phillips screwdriver with a shaft about 10" long. A multi-bit screwdriver won't work because the shaft is too thick. Just slide the screwdriver through the brackets to pull the screws out, pop the cover off, pull the springs, and fish out the vacuum pistons. Make your adjustments and reassemble. Make sure to drop the needle straight down, so that it goes into the collar above the emulsion tube; you can easily see if it doesn't. Put the screws and brackets back on, and you're good to go.

The big key to this is to not have sticky bolts... If they are stuck, you'll need to pull the carbs so you can put them in a bench vise and hit them with an impact driver.

Sláinte!