View Full Version : proper carb tuning?


NinjaPony
December 4th, 2020, 10:19 AM
from a start over perspective how do you tune your carbs? for proper idol etc. I am about to clean out my carburetor from my ninja 250ex 2004 and dont really know how far to open or what to open for that matter. the two bottom screws I think.

DannoXYZ
December 4th, 2020, 11:58 AM
Hi Anthony! :wave:

Not so much tuning as cleaning. If your bike has sat for more than 3-months, most likely it's got dried petrol clogging innards. You'll want to "clean" entire flow-path of petrol, from tank, through petcock, all hoses, jets, internal hidden & secret fuel passages all way to carb-venturi. Also replace all rubber seals & O-rings along way. "Cleaning" is lots of scrubbing with nylon brushes, ultrasonic soaking, and micro soda-blasting.

Search for "clean carbs ducatiman" for photos and procedures.

NinjaPony
December 4th, 2020, 11:42 PM
thank you for the help, now the only other issue I have is that I repositioned the clutch bar so that the pedal was more comfy and in the process I lost 2nd gear and up what did I do wrong?

Triple Jim
December 5th, 2020, 05:45 AM
thank you for the help, now the only other issue I have is that I repositioned the clutch bar so that the pedal was more comfy and in the process I lost 2nd gear and up what did I do wrong?

Do you mean the shift lever? If not please clarify "clutch bar". If you moved the shift lever and now it doesn't shift properly, take a close look at it and the linkage and see what's hitting or binding.

ducatiman
December 5th, 2020, 07:21 AM
If you are doing this with bike at standstill.....suggest to Google "Kawasaki positive neutral finder", Kaw shift linkage designed to upshift only while in motion
It is possible to defeat, btw, some parts removal necessary, but suggest leave it be!

AFA tuning....once circuits are truly clean and tuning component clearances restored to factory spec, metal to metal as intended (eliminating any varnish affecting those internal tuning clearances) pilot screw tuning done with bike hot, idling, turn pilot screw inwards (clockwise) till engine falters, back out till highest RPM achieved....repeat for other cylinder. This best accomplished after a truly precise manometer synch. If engine does not react or falter when a given pilot screw is turned in....that carburetors' pilot circuit is compromised, allowing entry of unmetered fuel, clogging, manifold issue....further diagnosis/correction required.

Prerequisites:
Important to assure adequate valve clearances! Check 'em!
Spark plugs correct, proper gapped, cap internals clean/tight
Air path clear, airbox to carb boots tight/secure as factory intended.
Fresh fuel, petcock clear, all vac hoses tight/secure.

NinjaPony
December 5th, 2020, 01:28 PM
before I adjusted the lever (clutch lever) at standstill, I would pretend to go through the gears and now I cant move the clutch up past neutral at stand still. I will try driving and going to 2nd gear, I haven't tried that yet. I haven't messed with anything other than adjusting the bar to better fit my foot.

DannoXYZ
December 5th, 2020, 05:20 PM
As mentioned, "positive neutral finder" feature won't allow shift into 2nd-gear unless rear-wheel is spinning.

Clutch is on right side of bike controlled by left handlebar lever.
Do you mean gearbox shift-lever on left side of engine?
Why did you adjust it? Improper adjustment will prevent clean shifts.
Should have set so shift-rod is exactly 90-degrees to each of little arms at each end.
One arm connects to foot-pedal and other arm connects to gear-box.

https://drive.google.com/uc?export=download&id=1gxcT7UMsrAifCj6kDaO5zAHNPkSK4G7h

NinjaPony
December 5th, 2020, 08:23 PM
yes thank you very much the bike runs and happy to say goes into higher gears once in motion but now when idoling it stays at 1500 or so RPM but all on its own it raises rpm all the way up to 4000 and slowly drops again. when I carb cleaned I turned the idol screws 2 1/2 turns from close. I need a group of local ninja riders to maybe check her out

DannoXYZ
December 6th, 2020, 01:40 AM
Your carbs need more thorough cleaning. Outlined above.

Many great mechanics. Who can remove engine in less than 15-minutes. Who can rebuilt engines in less than day. Have had to remove their carbs 4-5x for ever deeper cleaning before their bikes ran great. I suggest you do it 1st time around. Well, 2nd time now.

Here's some photos of what's involved. Need to scrub out all hidden secret passages in carb-body.
https://www.ninjette.org/forums/showthread.php?p=1267487#post1267487

Some related threads:

https://www.ninjette.org/forums/showthread.php?t=330960
https://www.ninjette.org/forums/showthread.php?t=322846
https://www.ninjette.org/forums/showthread.php?t=321223
https://www.ninjette.org/forums/showthread.php?t=317977
https://www.ninjette.org/forums/showthread.php?t=317810
https://www.ninjette.org/forums/showthread.php?t=316395
https://www.ninjette.org/forums/showthread.php?t=315193

And shortcut to get your bike running like factory-fresh off showroom floor in case you don't want to buy all equipment needed (scrub-brushes, ultrasonic cleaner and micro soda-blaster). Or spend decades learning how to restore carbs back to factory-fresh clean condition:

https://www.ninjette.org/forums/showthread.php?t=226815

VaFish
December 10th, 2020, 02:01 PM
The solution to your carb problem is simple.

Remove the carbs from your bike, ship them to Ducatiman. Send him some money via Paypal and He will quickly strip them clean them adjust them and send them back to you.

You will have a bike that runs like new if your valves are adjusted properly.

Emu
January 7th, 2021, 05:02 PM
Ship your carbs to Ducatiman, I was doing the same exact thing as you with no results. It is a super fast turn around. It was honestly the best money I have ever spent on the bike. Until you get everything you need to do a full carb job yourself I would rely on someone more experienced the same way I am.