what is the best idle screw mixture

vmax · May 21st, 2013, 08:06 PM

Hi all,

I just want to know what is the best screw mixture for ninja 250r when I put slip on or full system exhaust, cause i have try those instalation and set idle mixture both same 2,5 or different half between left and right but my spark plug colour still white porcelin. I do know even with stock needles mainjet 98 still rich on top.
For information my setting :
- stock needles with 1 or 2 washer each
- stock air filter
- pdk slip on or cld full system

I try those combination but my spark plug still bone white. Low and midrange was fine but top end was suffer, kind a hard to pass 9k.
I set my idle screw now 2,5 left and 2 right.

subxero · May 21st, 2013, 08:20 PM

so you have an exhaust that changes from a slip on, to a full exhaust? pretty cool stuff there.

In short, from the sounds of things your idle mixture screws are the least of your worries and have little to no effect on your air/fuel ratio past 1/8th throttle.

Figure out if you have a slip on, or a full exhaust, if you can't then things are far worse than i originally thought. Figure out exactly how many washers you have shimmed. Not 1 or 2.

Slip on should not require much changes to jetting if at all if my memory serves me correctly. A full exhaust will require tuning all the circuits of the carb. You can probably get away with the stock #38 pilot jet, but the needles and main jet will need adjusted, once you get the main circuits tuned go back and fine tune your idle mixture screws.

Lastly are you doing your plug checks correctly?

If you have any questions please see any or all of the carb Do It Yourself (DIY) threads in the sticky section at the top of the tech section.

vmax · May 21st, 2013, 10:15 PM

Hi Joe,

thanks for your reply. I already try my needles with 1 and 2 washer each, but my spark plug still white with a little black colour on outside ring. When I put 2 washer each needles, the thortle seem to heavy on midrange. So any idea my idle screw mixture?

subxero · May 22nd, 2013, 06:52 AM

every bike is different, just turn them till your bike sounds happy. once you get the idle screws running somewhat normal again. Go back and start tuning the other circuits without messing with the idle circuit, do it last after you get everything else figured out. It is trial and error and may take 10-15 different adjustments before you finally get it right.
Just try and find other information on the web about how to tune a carb and what each circuit effects.

DaBlue1 · May 22nd, 2013, 07:46 AM

Quote:

Originally Posted by vmax

Hi Joe,

thanks for your reply. I already try my needles with 1 and 2 washer each, but my spark plug still white with a little black colour on outside ring. When I put 2 washer each needles, the thortle seem to heavy on midrange. So any idea my idle screw mixture?

With a slip on, one washer does not make a whole lot of difference. (for the best results they should be at least 1 mm combined thickness.)
Set the idle mixtures to 2.5 turns or leave them alone.
Remove the snorkel and test to see if you can go past 9k. A little more air will help get past that rich zone.
Don't worry about your plug color at this point. White-grayish looking plugs are normal.

From NGK website

How to Read Your Spark Plug

FAQ Reading Spark Plugs

vmax · May 22nd, 2013, 07:45 PM

hi Blue,

thanks for your information, I am glad my spark plug normal, I did try to remove snorkel as your sugestion, bike can pass 9k but still heavy, what I feel after remove snorkel, low end seems little bog and top end still heavy. Is this syptom that ninja rich on top? cause what I read from all forum, ninja lean on midrane and reach on top. So should I change the MJ 95?

DaBlue1 · May 22nd, 2013, 08:00 PM

Quote:

Originally Posted by vmax

...So should I change the MJ 95?

You could, but try an aftermarket drop in filter first.

KikRox · July 1st, 2017, 10:23 AM

ahhh!!! NO. dont set both mixture screws to 2.5 with stock needles and air box! the stock airbox has some flow issues and to compensate kawi has tune the two carbs differently to compensate.

baseline for with airbox is 2.5 out left, 1.75 out right.

Triple Jim · July 1st, 2017, 10:39 AM

You shouldn't set the idle mixture screws at any particular place. A couple good procedures for adjusting them are here: https://faq.ninja250.org/wiki/How_do...dle_mixture%3F

Numbers like 2-1/2 turns are just starting points to get the engine running so you can actually adjust them properly.

KikRox · July 1st, 2017, 10:45 AM

word. i am having issues articulating a paragraph today. i edit my post like 6 times... way to tired heh.

May 21st, 2013, 08:06 PM	#1
vmax ninjette.org member Name: max Location: bali Join Date: Nov 2012 Motorcycle(s): ninja 250 Posts: 60	what is the best idle screw mixture Hi all, I just want to know what is the best screw mixture for ninja 250r when I put slip on or full system exhaust, cause i have try those instalation and set idle mixture both same 2,5 or different half between left and right but my spark plug colour still white porcelin. I do know even with stock needles mainjet 98 still rich on top. For information my setting : - stock needles with 1 or 2 washer each - stock air filter - pdk slip on or cld full system I try those combination but my spark plug still bone white. Low and midrange was fine but top end was suffer, kind a hard to pass 9k. I set my idle screw now 2,5 left and 2 right.

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May 21st, 2013, 08:20 PM	#2
subxero dirty boy Name: Joe Location: Johnstown, PA Join Date: Sep 2012 Motorcycle(s): I don't even know anymore?? Posts: A lot. MOTM - Apr '14	so you have an exhaust that changes from a slip on, to a full exhaust? pretty cool stuff there. In short, from the sounds of things your idle mixture screws are the least of your worries and have little to no effect on your air/fuel ratio past 1/8th throttle. Figure out if you have a slip on, or a full exhaust, if you can't then things are far worse than i originally thought. Figure out exactly how many washers you have shimmed. Not 1 or 2. Slip on should not require much changes to jetting if at all if my memory serves me correctly. A full exhaust will require tuning all the circuits of the carb. You can probably get away with the stock #38 pilot jet, but the needles and main jet will need adjusted, once you get the main circuits tuned go back and fine tune your idle mixture screws. Lastly are you doing your plug checks correctly? If you have any questions please see any or all of the carb Do It Yourself (DIY) threads in the sticky section at the top of the tech section.

May 21st, 2013, 10:15 PM	#3
vmax ninjette.org member Name: max Location: bali Join Date: Nov 2012 Motorcycle(s): ninja 250 Posts: 60	Hi Joe, thanks for your reply. I already try my needles with 1 and 2 washer each, but my spark plug still white with a little black colour on outside ring. When I put 2 washer each needles, the thortle seem to heavy on midrange. So any idea my idle screw mixture?

May 22nd, 2013, 06:52 AM	#4
subxero dirty boy Name: Joe Location: Johnstown, PA Join Date: Sep 2012 Motorcycle(s): I don't even know anymore?? Posts: A lot. MOTM - Apr '14	every bike is different, just turn them till your bike sounds happy. once you get the idle screws running somewhat normal again. Go back and start tuning the other circuits without messing with the idle circuit, do it last after you get everything else figured out. It is trial and error and may take 10-15 different adjustments before you finally get it right. Just try and find other information on the web about how to tune a carb and what each circuit effects.

May 22nd, 2013, 07:45 PM	#6
vmax ninjette.org member Name: max Location: bali Join Date: Nov 2012 Motorcycle(s): ninja 250 Posts: 60	hi Blue, thanks for your information, I am glad my spark plug normal, I did try to remove snorkel as your sugestion, bike can pass 9k but still heavy, what I feel after remove snorkel, low end seems little bog and top end still heavy. Is this syptom that ninja rich on top? cause what I read from all forum, ninja lean on midrane and reach on top. So should I change the MJ 95?

July 1st, 2017, 10:23 AM	#8
KikRox ninjette.org member Name: Nein Location: Canada Join Date: Jun 2017 Motorcycle(s): 2011 Ninja 250r se Posts: 100	ahhh!!! NO. dont set both mixture screws to 2.5 with stock needles and air box! the stock airbox has some flow issues and to compensate kawi has tune the two carbs differently to compensate. baseline for with airbox is 2.5 out left, 1.75 out right.

July 1st, 2017, 10:39 AM	#9
Triple Jim Guy Who Enjoys Riding Name: Jim Location: North Carolina Join Date: Jul 2016 Motorcycle(s): Ninja 250 Posts: A lot. MOTM - Oct '18, Aug '17, Aug '16	You shouldn't set the idle mixture screws at any particular place. A couple good procedures for adjusting them are here: https://faq.ninja250.org/wiki/How_do...dle_mixture%3F Numbers like 2-1/2 turns are just starting points to get the engine running so you can actually adjust them properly.

July 1st, 2017, 10:45 AM	#10
KikRox ninjette.org member Name: Nein Location: Canada Join Date: Jun 2017 Motorcycle(s): 2011 Ninja 250r se Posts: 100	word. i am having issues articulating a paragraph today. i edit my post like 6 times... way to tired heh.