Carb'ed 250R idles but stalls on rev

[Justanothermp5]

So Im out of ideas. I had the carbs out of the bike for the 8th or 9th time now and it still just starts, runs, but as soon as I hit the throttle it stalls and shuts off. Ive cleaned the jets, they had a little debris in the jets, so I soaked them in baking soda solution over night and it cleaned all the crud out. Could see thru the jets with no issue. Diaphram was torn, bought a new one, installed it, same issue. Gas was old, bought fresh gas, drained the tank, new gas...and wouldnt you guess it. SAME ISSUE.

Ive cleaned everything there is to clean, I have no idea what it could be. Bike ran fine but just stopped starting after a long sit at my parents house. Only thing I could think of is if I installed anything wrong in the carb, the slides to be exact. Which way does the hole face in the slide, the engine side or intake side?


Any other input would be great. Im trying to fix it for my dad to ride, but its looking like a lost cause and I dont want to sink anymore money into it. Thanks in advance.

Should also note, that after the last time of me taking it apart, cleaning the jets, it idles with no choke. before it would die as soon as I took the choke off. So I know its getting fuel into the carbs, its just not adding fuel when I open the throttle?

[Racer x]

At idle the fuel come through ports and those ports are regulated by the screws on the bottom of the carb. Make the 2 or 3 turns out to start. Then as the throttle is opened fuel comes through the pilot jets. I would replace them. They are probably the problem. Alcohol in the fuel causes them to corrode and become smaller. Then the needle regulates the fuel through the main jet till it's just the main.

If you rev the engine a little at a time can you get the engine to rev high? What exhaust and filter are you using?

[Justanothermp5]

Originally Posted by Racer x

At idle the fuel come through ports and those ports are regulated by the screws on the bottom of the carb. Make the 2 or 3 turns out to start. Then as the throttle is opened fuel comes through the pilot jets. I would replace them. They are probably the problem. Alcohol in the fuel causes them to corrode and become smaller. Then the needle regulates the fuel through the main jet till it's just the main.

If you rev the engine a little at a time can you get the engine to rev high? What exhaust and filter are you using?

Any change to the throttle and it cuts out, not even if I slowly open it does the idle go up. Even with the choke all the way on it barely rev above 3-4K and sounds like its stuttering, never a constant rpm. Im on OE filter with snorkel removed, Area P full exhaust, and a Dynojet Jet kit. Unsure of the jet size at the moment because I installed them a few years ago, but it ran great until it sat at my parents house.

[Racer x]

It's the sitting part that gets them. Get some gum cutter. Or even starting fluid and while trying to open the throttle spray something in there. If it revs up then you have a fuel restriction someplace.

[Justanothermp5]

Originally Posted by Racer x

It's the sitting part that gets them. Get some gum cutter. Or even starting fluid and while trying to open the throttle spray something in there. If it revs up then you have a fuel restriction someplace.

Thanks for the help man, I just yanked the carbs again. The main jets are as clear as can be but the pilot jets have a hole that is barely big enough to see light thru. Both are the same, is this normal or should it be a bit larger?
BTW I checked the jets, they are 100s. I remember they were bigger then they should be but I planned on upgrading the filter and didnt want to pull the carbs again (ironic)

So replacing the pilots is the only place to go from here? or is there something else I can try first. I checked the slide direction and its correct. so Im thinking maybe my vac lines arent hooked up right or something so the slide is popping up and letting more fuel in. Just a theory

[Racer x]

I don't know the dyno jets by number. I would replace the pilots. With the full exhaust you should be just a little rich on the mains. Hotter plugs are good. But not your immediate problem.

[Racer x]

The pilots have very small holes. The seem to be very sensitive.

[jkv45]

If the Main Jets are open, I would say something is assembled incorrectly. Just being able to see light through a jet doesn't mean it's open. You need to take a fine copper wire and run it through the jet while spinning it to make sure it's fully open. Then spray with carb cleaner and blow-out with compressed air.

Is there any debris in the floatbowls?

If it idles fine the Pilot Jets aren't the issue. As soon as you open the throttle the slides lift and the fuel begins to flow through the Main Jet.

Either the slides are not lifting as you open the throttle or there is not adequate fuel flowing for some reason.

Check that the slides rise and fall smoothly and that everything is assembled correctly.

Read through this section - http://faq.ninja250.org/wiki/Intake. Especially the "How do I work on the carbs" part to confirm you have them assembled correctly.

[InvisiBill]

I had the same problem on my Vulcan when I reassembled them incorrectly. The spring seat (little plastic piece with legs) goes above the needle, on top of the slide/diaphragm. At least on the Vulcan's part, there was a little impression on top of the spring seat that perfectly matched the top of the needle, causing me to accidentally put the needle on top of/through the spring seat. This essentially shims the needle a ton, screwing up the fueling. Proper order is slide/diaphragm, needle, spring seat, spring, cap.

http://www.kawasaki.com/Parts/PartsD.../2012/EX250JCF

[Justanothermp5]

Okay so I cleaned everything again, there was this odd green buildup on the inside of the hole where the pilot jet sits. Cleaned that off, soaked everything in carb cleaner again. Everything appears clean as can be. No debris in the bowls or anywhere. I also took the time to drill the caps off and adjust the screws on the bottom of the carbs. 2 to 3 turns out means 180 or 360 degree turns?

But besides that, everything was assembled correctly, the plastic 4 prong thing was on top of the needle pushing it down, everything slides smoothly. If it doesnt work this time Ill be completely baffled.

[Ghostt]

Originally Posted by Justanothermp5

Okay so I cleaned everything again, there was this odd green buildup on the inside of the hole where the pilot jet sits. Cleaned that off, soaked everything in carb cleaner again. Everything appears clean as can be. No debris in the bowls or anywhere. I also took the time to drill the caps off and adjust the screws on the bottom of the carbs. 2 to 3 turns out means 180 or 360 degree turns?

But besides that, everything was assembled correctly, the plastic 4 prong thing was on top of the needle pushing it down, everything slides smoothly. If it doesnt work this time Ill be completely baffled.

Assuming the carburetors are clean, and all is functioning properly, including the petcock, here is my write-up on pitch screws tuning, and yes it 3 full turns out from the bottoming them out. Did you verify all the fuel circuits were clear with a air compressor? Did you remove the main jet holders? The idle mixture screws? Are the emulsion holes all clear?

Your initial setting should be 3 full turns out from the bottom, remember just slightly tighten them, don't go all Conan on them.



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.*

Thats a quickie, 10 cent tutorial on setting pilot screws.**

PM @ducatiman for your carburetor needs.

[ducatiman]

1 turn = 360 degree= 1 "full turn"

the green discoloration indicates fuel dropout has occurred, that slime tends to
constrict tiny passages within various circuits, particularly the pilot.

Are you using compressed air in your cleaning attempts?

I'd suggest removing both the pilot jet and pilot screw (beware the spring, tiny washer and oring) spray some carb cleaner down the ports and blow back and forth between the 2 ports alternately with compressed air. A 012" guitar string "poke" will open the pilot jet back to its intended opening.

Give that a try.

PM me if you'd like your carbs split, treated ultrasonically and sodablasted, float valves, all orings replaced and fuel level set up correctly.

[Justanothermp5]

WAIT A SECOND. Just to be 100% clear. Piece 16017 goes in from the top of the carb or the bottom before the main jet holder?

Also, used compressed air on everything. All the holes blew out air and carb cleaner, no debris in anything except the first time I cleaned the pilot jets. I put the carbs back in and same problems. Petcock is draining fine, so no restriction there. Bowls fill up with fuel as soon as I turn to Prime, I can hear the tank venting. I started the bike up and Perfect idle. Even stone cold I barely had to use the choke. Stone cold is 90 degrees ambient temp tho LOL

Im stumped. Besides that little pieces position. Im lost.

[Justanothermp5]

Oh man
I think I figured out the problem. Ill await a response to my main question in the above post before I yank the carbs tho. I hope thats what it is....

[ducatiman]

16017 is the needle jet and is inserted first into the main mixing chamber under the "main jet holder" (actually the emulsion tube)

the longer (open) end goes in first

After the main jet holder is installed, 16017 should show in the venturi as a little "collar" protruding a bit.

The diaphragm jet needle is gonna stick into it (technical term)

Did you install the needle jet in from the venturi side (wrong) or the underside (correct)?

[Justanothermp5]

LOL. So...I def installed that in thru the top instead of before the main jet holder. I was just thinking to myself, "how the hell is this thing supposed to stay in there." Well now that I actually know how to correctly assemble a carb, I will go do that and Im sure you will hear good results. For some reason I remebered always going thru the top. But thats probably why the bike hasnt ran in a while....
Thanks for the huge amount of help guys. Unfortunately it was just human error as usual on my end.

[Racer x]

A picture is worth a thousand words.

[Justanothermp5]

As you can see from the pics, Im a dumbass. Not only did that collar being incorrectly installed not allow the needle to move when I revved the bike, it also had the slide sitting up way to high. I installed everything properly, put the carbs on. And its back to normal. Still needs thr choke to start, once it runs for a min or 2 I take the choke off and it revs free as can be. I finished at like 11pm and my Area P exhaust screams, so In going to take it for a quick ride this morning to insure all is well. First time Ive ridden this thing in almost 2 years lol

[ducatiman]

super, sounds like you got it solved

you're fortunate one didn't dislodge and get sucked into the intake trac

[Ghostt]

Seriously lucky

[Justanothermp5]

Originally Posted by ducatiman

super, sounds like you got it solved

you're fortunate one didn't dislodge and get sucked into the intake trac

Tell me about it, had it been able to rev Im sure it would have. Dodged a bullet on that one.
I gave it a test ride around the block and it runs great. Slow as hell but it screams when I give it gas lol forgot how loud this thing was.

Thanks for all the help guys!