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Discussion Starter · #1 ·
hey guys, great forum :)

i need some help with my carb settings and cannot find much through search for specific settings...
2010 250R
since changing my exhaust to a high flow can (slipon) nothing has felt right. I took it to a dynotune for the carbs but it came out worse!

long story... but at the moment i am running the needles at 2x stock height (two stock washers on each needle) with the mix at 3turns out. the main jets should be okay since they came from a carb tune pack but im not sure of their size. they were changed by the mechanic whilst 'tuning'

I am running the K&N pod with slipon as mentioned and the bike runs like shit over 9K. it has **** all power. i dont no whether its rich or lean but i need help!

what are some settings that you guys have been running? i need a baseline to work from. any combinations that have worked well?
i dont even know the stock settings anymore??? :facepalm:

I have tuned my cbr250rr with a slipon and airbox mods beautifully but i just cant get this ninja to work!!! :facepalm:

what are u running???
 

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Hey Mat,

welcome to NN! I don't mean to point you away from this forum, for it is my home and I love it, but you might want to check here: Jetting Database - Discussion Thread - ninjette.org

stock settings:
idle jets: 38
main jets: 98
idle/mix: 3 turns out.

needles at 2x stock height? you using dyno jet needles with the clip? You using stock needles with washers? Clip position or amount of washers would be best...

What elevation are you at?

If everything is functioning as it should - the diaphragms haven't been pinched, you don't have a vacuum leak etc, considering your mods, this would be a good baseline for you to start at...

idle: 38
main/idlemix/dyno jet needle position: 100/2.5 turns out/3rd clip from the bottom, 102/2 turns out/4th clip from the bottom.
dyno jet needle position: 3rd slot from the bottom.

Not sure about your tuning experience, but here are some guidelines:
idle jet - adjust AT IDLE ONLY
air/fuel mix - adjust throttle to 20%
main jet - throttle from 20% to WOT
needle position - throttle form 20% to WOT
3 air/fuel turns out = 1 idle jet size
3 clip positions on needle = 1 main jet size
 

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You said it runs terrible over 9000, I'm assuming you mean at WOT. The RPMs aren't as critcal as the throttle position.

If it's barely running at WOT, look at the size of the main jet. Just because it was in the kit doesn't make it the right jet. Mistakes do happen. Search around and see if you can determine what size you should be starting with, and compare it with what you have.

If all else fails, go back to your stock parts and move richer from there.

On the street, with the Ninja, I'd go with an airbox instead of pod filters. The pods are going to soften your throttle response and power until you are way up there. The Ninja can use all of the midrange it can get.


Jay
 

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Discussion Starter · #4 ·
Thank u guys. helping heaps :) my needles are stock (not clipon) with 2 stock washers under each... With the mix... All the way in is lean? And winde out to make it richer? Or is it the opposite with these carbs? This could be the source of my problems....elevation is sea level
 

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Here's some carb info that spooph posted in another thread - DIY - Accessing and adjusting idle mixture screws - ninjette.org

From the ninja250.org FAQ section on carbs - "Turning the screws IN decreases the amount of gas at idle (leans it out). Turning the screws OUT increases the amount of gas at idle (richens it)."


So the idle adjustment screw is a fuel-bleed, not an air-bleed like some.


Jay
 

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Discussion Starter · #6 ·
thanks jay!

spooph, i was looking at your recommendations, you are saying that as the main jet gets bigger, less fuel must be mixed? is this because the jet can now "suck up" a larger volume of fuel? i was under the impression it was the other way (i understand that fuel&air must be within ratio however... it just seems the ninja should be capable of more... i will find out what my jet sizes are and be sure to get back to you guys :)

perhaps a thread with peoples mods and specific carb specs could be set up to help out in the future :angel:

mat
 

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Oh dear.... matv's reading comprehension needs to be increased....

I posted that link dude...

Also, not sure what you're saying. A bigger jet = more fuel. The relationships I gave you:
main/idlemix/dyno jet needle position: 100/2.5 turns out/3rd clip from the bottom

OR

102/2 turns out/4th clip from the bottom.

are just slightly different, the second one being a bit richer than the first one. I was also trying to show the relationship between the various variables to grow your understanding of the system.

Now, get those jet sizes so we can figure out what your problem is. BTW, I agree with JKV, he knows what's up.
 

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Discussion Starter · #9 ·
lol! my bad.

the jets in there are 105s

working on it today I was planning to set it to 110s, 2 - 2.5 mix and third to forth from bottom on the needle (equivilent) any suggestions? i would prefer to run the 110's as it seems to be a popular choice with the pod and exhaust, unless u seriously advise against it?
 

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Discussion Starter · #10 ·
okay so i put the 110 jets in. set the mix at 2.5 turns and the needles at third from top with one shim (equivalent)

it seems to stutter a little at 9k on WOT then at 10-12 it sputters and wont climb any further WOT. it sounds like it will stall and has no power

it can go up to redline but only when pushed through gently.
the diaphragms are not damaged and there seems to be no vacuum leaks. I have taken out the air box and am running filters on the breather hoses that used to be attached to the airbox.

also
on the bottom of the slides, next to where the needles come through, there are pilot holes? im not sure what to call them. im assuming the way they face is important... do the pilot holes, next to the needle holes, go closer to the engine side, or the filter side?

it does pop (slightly) on de-acceleration and when i pulled the in the 'choke' when riding it popped majorly on de-acceleration.

its symptoms seem all to be at WOT. please don't give up on me guys :( im struggling
the help so far has been amazing
 

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The engine is always fully warm when you test, right?

One thing you could try to help decide which way to go on the main jet would be to add some choke (when fully warm) when you are testing the mixture at WOT.

If the problem gets better with choke (1/4 or so) you know the jetting is lean. You can also pull the plug, but to read the plug you are best with a new one and need to run very little except at the RPMs you want to test. To do it properly you really need to "chop" the throttle and read the plug without any additional running - pretty much a pain on the street.

I would at least look at the plug now and clean it up, then check it again later.

If you had someone behind you when it was stumbling they may be able to see black smoke if it was rich. Take a look at the end of the muffler to see if there is any amount of black soot on it. Clean it off and see if it returns.

If you get really stuck you could post a video to help us try to figure out what's going on. Just don't rev it to those RPMs when it's just sitting there, find some way to get shots of the problem when you are riding.


Jay
 
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