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Old October 20th, 2018, 06:01 PM   #1
dodgerdad
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idle adjustment or air mixture

I purchased a non-runner that i got running but would only idle (around 5000 rpm) with the choke open. I removed the carbs to clean them up. Both sets of jets were a bit clogged. I didn't mess with the air mixture screws because they were sealed still, but oddly, the plug/seal was VERY recessed.

I've seen videos on drilling out the air mixture screw plugs but mine are so recessed that I was worried about damaging the actual screw heads.

I reassembled everything and the bike fires right up. It can idle as low as 1900-1800 with the choke slightly opened. I can close the choke and it still runs and can be revved up, but just can't quite idle without cutting out.

Do you guys think adjusting the idle can resolve it or should I bite the bullet and drill out plugs covering the mixture screws and clean/reset the air mixture screws?
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Old October 20th, 2018, 06:19 PM   #2
Snake
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Sounds like the air mixture screws need adjustment!
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Old October 20th, 2018, 09:07 PM   #3
maverick9611
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drill it. use a bit that is medium size for the plug. drill in slow. the bit usually grabs the plug and your done. just pull back when the plug is free. i highly recommend a motion pro carb adjust tool.
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Old October 20th, 2018, 09:12 PM   #4
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air mixture tweaks

i use ghostt quickie pilot 101
start at 3 turns out
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.*
as per ghostt
i use 1500 for idle, easier to see rpm and gauge it.
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Old October 21st, 2018, 07:35 AM   #5
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You want to remove the caps, screws w/o-rings and washers, and clean the passages. Also remove the Pilot Jets and clean them carefully.

Geneally 2.5 turns out is a good starting point, and usually richer that the factory setting (check it before you remove them), which helps with a better idle and smoother throttle transitions off-idle. Idle speed is around 1300 normally. Cold air and gas with ethanol will require a slightly leaner adjustment to be optimum.

Here's more info about the process - https://faq.ninja250.org/wiki/Intake
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Old October 21st, 2018, 08:23 AM   #6
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If you haven't uncapped and removed the pilot adjust screws and cleaned that passage, your idle circuits are not truly clean.

Before any cleaning with chemicals, remove the diaphragm/slide assemblies to prevent collateral damage to the rubber diaphragms.

Next remove both pilot screws AND pilot jets, leaving them aside, using your preferred cleaner...
spray into each opening, let them sit a bit...finally using strong compressed air to blow back and forth between the 2 openings. .

Pull the emulsion tubes...then, on the lower part of the "bells" on the intake side, the 2 tiny air correction jets (1 is for the pilot circuit, 1 is for main circuits) do a spray and soak, then blow them out as well.

As an aside....."looking like new inside" (we read about so often) is not a true measure of "clean carbs". The tiny, important hidden circuits ARE NOT visible by eye and must be aggressively treated during a cleaning as if they were clogged.

Oh, the pilot screws will have a tiny spring, washer and oring....you must account for their whereabouts and replace in the exact same order. Best to renew the orings while in there. A basic starting point for the pilot screws is 2.5-3 turns from lightly seated.

Any time when servicing carbs, float bowl gaskets and pilot orings should be on hand before starting. Leaks are unacceptable.

Good luck with your efforts.
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