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Old October 31st, 2021, 06:08 PM   #1
Vansaki
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K&N #KA-2586 Air Filter

Besides modifying the air box cap, does using this air filter require any carb re-jetting or anything like that? Does anyone have any experience with this filter?

Thanks !
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Old November 1st, 2021, 10:10 AM   #2
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MOTY - 2018, MOTM - Nov '17
No changes needed for stock performance.

For improved power, typically want to downsize main-jets couple sizes for more power (to compensate for super-rich top-end)
And shim needles about 1.5-2.0mm to make up for leaner mid-range.

Last futzed with by DannoXYZ; November 6th, 2021 at 02:38 PM.
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Old November 1st, 2021, 10:31 AM   #3
Vansaki
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downsize mains couple sizes ??
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Old November 1st, 2021, 12:10 PM   #4
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Yup, factory jetting is super-rich, too much fuel for safety. Makes for smoother-running engine with less than max-power possible. No OEM manufacturer would ever tune for max-power, that's crazy and opens them for major liability.

In event you get bad petrol from station out in boonies. Or riding on super hot day or radiator clogs or leaks and overheats. Or have clogged carbs from sitting. You'll end up running lean, not sufficient fuel, and end up blowing headgasket, or punching holes in pistons. So factory jetting is always too rich for safety rather than leaner for max-power. It's typically in 10.0-11.0:1 AFR range whereas max-power occurs at 13.5:1 for NA engines.

So to extract more power, you'd lean out WOT mixtures by using smaller main jets. Remember that '60s hot-rod saying...
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Old November 6th, 2021, 06:58 AM   #5
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Originally Posted by DannoXYZ View Post
Yup, factory jetting is super-rich, too much fuel for safety. Makes for smoother-running engine with less than max-power possible. No OEM manufacturer would ever tune for max-power, that's crazy and opens them for major liability.

In event you get bad petrol from station out in boonies. Or riding on super hot day or radiator clogs or leaks and overheats. Or have clogged carbs from sitting. You'll end up running lean, not sufficient fuel, and end up blowing headgasket, or punching holes in pistons. So factory jetting is always too rich for safety rather than leaner for max-power. It's typically in 10.0-11.0:1 AFR range whereas max-power occurs at 13.5:1 for NA engines.

So to extract more power, you'd lean out WOT mixtures by using smaller main jets. Remember that '60s hot-rod saying...
Yes your right as all OEM manufacturer will de-tune there engine by as much as 15-20% from max-power rate unless you got a Hell Cat Engine.

That all depend on altitude as factory jetting is not always super-rich that is why EFI is more superior as it can correct for those variables
There many thing but typically AFR is around 12.5:1 to highside 13.5:1 as there are a lot of other factor that come in to play from Cam to Head Chamber Shape as well as Compression Ratio and even right to Timing Curve.
10.0-11.0:1 AFR range in more inline for E85
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Old November 6th, 2021, 12:52 PM   #6
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We need to look at specific models and their factory configurations. Ninja 250 is super-rich in OEM trim. Nowhere is it leaner than 11.8 and mostly in 10-11.0 range under WOT. Ignore beginning of this chart as it's recording delay of slides when throttle is 1st opened. This bike actually has snorkel removed and K&N filter for more air-flow and it'll still way too rich.



It's so rich, that brand-new plugs look like this on stock street bike after 20-min session on track. Not many people use constant WOT very often, other than starting from red-light or getting on freeway. You're missing out on A LOT of power with that much fuel. Both these bikes were on track within same hour.



Compared to my track 250 with full Tyga exhaust and free-flow filter (right). It's got 22% more flow than stock and +22% more power AND it has 2-sizes smaller main-jets than stock. Not to mention the DynoJet needles are thicker at tip than stock to reduce high-end fuel even more. So my track bike is effectively running 3-sizes smaller jets along with all of the higher flow upgrades compared to street bike.



SportRider - Racing on the Cheap - scroll down to "The Nuts and Bolts" section on dyno-tuning. With Area-P full-exhaust, they flowed 18% more air and made +18% more power than stock AND went from factory 98 main-jets down to 95. Area-P exhaust makes about 1-hp less than Tyga.

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Old November 6th, 2021, 01:09 PM   #7
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MOTY - 2018, MOTM - Nov '17
Even Ninja 250FI model is programmed with rich top-end. Not as bad as carby models, but can still use some leaning out for more power. Notice erratic AFR curve on stock bike. Just reducing fuel to more optimal flat 13.5 AFR picks up torque and power across board. That's +14% more power with no upgrades, just reducing fuel.



Note that bone-stock EFI 250 with just remapped fuel makes more power than intake-upgraded carby 250. When upgraded with full-exhaust, free-flow intake and dyno-tuned, EFI models ends up with +5hp more than carby model with exact same mods.

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Old November 9th, 2021, 11:58 AM   #8
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On my stock bike it reading lean on plugs with 35 Pilot Jet and 105 Main jet with stock exhaust as just clean out carb today to rid some junk and install new fuel petcock rebuild kit
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Old November 9th, 2021, 01:04 PM   #9
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Quote:
Originally Posted by shspvr View Post
On my stock bike it reading lean on plugs with 35 Pilot Jet and 105 Main jet with stock exhaust as just clean out carb today to rid some junk and install new fuel petcock rebuild kit
your '07 should have a 38 pilot, no?
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Old November 9th, 2021, 01:33 PM   #10
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your '07 should have a 38 pilot, no?
Your right it 38 one has poor marking kind of look like a 5 the other one saying 38 and needled are both I think it was N161 or N16I in any case I look like I need go with stage 1 38 108 or stage 2 40 110.
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Old November 9th, 2021, 02:20 PM   #11
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Any chance it's running lean due to partially clogged carbs like mine was when I got it?
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Old November 9th, 2021, 02:57 PM   #12
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Any chance it's running lean due to partially clogged carbs like mine was when I got it?
That I don't know Jim but I did go thru every bit of it with nylon brush/wire kit that come with my new replace weed eater carb but didn't remove Pilot Jet Screw Cap as all drill bits I have are way to big there 3/8 on up but I did drop in some new float needled as old ones look to bit a old and tried.
I have get a smaller drill kit in order to remove those dumb cap next time .
Waiting on the upper fiberglass fairing to get here so I get start on prepping painting for all body parts and still haven't decided on a color maybe orange or lime green.

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Old November 9th, 2021, 04:28 PM   #13
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I did go thru every bit of it with nylon brush/wire kit that come with my new replace weed eater carb but didn't remove Pilot Jet Screw Cap
Aside from resetting the screw adjustments.......you've neglected a critical carb passageway there.
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Old November 9th, 2021, 04:59 PM   #14
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Yes, no wonder it's running on leaner side. Pilot jet has numerous lateral bleed holes that needs to be poked out with wire. Same with pilot bleed-hole in carb-venturi, needs to be poked backwards from there..



BTW, did you poke out all lateral bleed holes in emulsion tube too? Ultrasonic soak? Micro soda-blast?

Again, no need to ever increase jet-sizes on these bikes. They ran perfect when leaving showroom floor. The only thing that changed over time is carbs got dirty and clogged. So.. obvious fix is to reverse that process by properly cleaning them until they are factory-fresh clean. If bike doesn't run like brand-new off showroom floor, then carbs aren't factory-fresh clean. Simple.

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Old November 9th, 2021, 05:09 PM   #15
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Aside from resetting the screw adjustments.......you've neglected a critical carb passageway there.
Ture as I still need a drill bit to remove those caps at time as I try to get ready for motorcycle license test and inspection that or I would to wait in tell next year so mad dosh to get every work you know light turn and horn and so on I made the bike run well enough and pass the written and drive test .
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Old November 9th, 2021, 07:07 PM   #16
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having replacement pilot screw orings on hand may be a wise idea as well.
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Old November 10th, 2021, 03:42 AM   #17
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having replacement pilot screw orings on hand may be a wise idea as well.
All ready got those O-Rings just need to get them install .
The Air Cut Off Valve and O-Ring look ok but I plan replace them too.
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Old November 10th, 2021, 04:22 AM   #18
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Originally Posted by DannoXYZ View Post
Yes, no wonder it's running on leaner side. Pilot jet has numerous lateral bleed holes that needs to be poked out with wire. Same with pilot bleed-hole in carb-venturi, needs to be poked backwards from there..



BTW, did you poke out all lateral bleed holes in emulsion tube too? Ultrasonic soak? Micro soda-blast?

Again, no need to ever increase jet-sizes on these bikes. They ran perfect when leaving showroom floor. The only thing that changed over time is carbs got dirty and clogged. So.. obvious fix is to reverse that process by properly cleaning them until they are factory-fresh clean. If bike doesn't run like brand-new off showroom floor, then carbs aren't factory-fresh clean. Simple.
All the bleed holes are clean with help of my to Oxygen-Acetylene torch tip cleaner even used a magnifying glass just be sure, No need for soda-blast the inside of the bowl was petty clean even the outside look clean too all most like new which was kind of a big surprised, unlike other carb from 05 which is a mess and dirty, I guess I can't complain as I got both 05 and 07 of for $300 .
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Old November 10th, 2021, 07:22 AM   #19
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What a deal!!! That's amazing! I picked up pair of 2002 and 2003 for similar price from storage-auction. But they were bare frames and parts in boxes needed to be assembled. A ninjette jigsaw puzzle!

Dried petrol fragments hang around as chads on inside of pilot after poking lateral holes. Then they get picked up by petrol flow and clog bleed hole in carb venturi. Soda blasting clears out hanging chads. Also need to poke out bleed hole in carb venturi as well.
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Old November 10th, 2021, 08:34 AM   #20
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Originally Posted by DannoXYZ View Post
What a deal!!! That's amazing! I picked up pair of 2002 and 2003 for similar price from storage-auction. But they were bare frames and parts in boxes needed to be assembled. A ninjette jigsaw puzzle!

Dried petrol fragments hang around as chads on inside of pilot after poking lateral holes. Then they get picked up by petrol flow and clog bleed hole in carb venturi. Soda blasting clears out hanging chads. Also need to poke out bleed hole in carb venturi as well.
Working it now got drill bit remove those pesky cap
Odd one pilot screw was only set 3/4 of turn on cyl 2 clutch side the other 2 1/2 on cyl 1 mag side
What the stock Pilot Screws setting

True there but I'm gone to using a pressurized solvent on pilot passage base on N4MWD's blog on Secret Ninja 250 Carburetor Passages

Got her back to together running much better and set both Pilot Screws 2 1/2 for now then the rain come ah rats guest I have re-sync the carb some other day and address the idle

Last futzed with by shspvr; November 10th, 2021 at 07:26 PM.
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