Ninja 250 idles fine idle increases drastically as it warms up

[MAZ 80]

Originally Posted by spooph

Yes, my bike and RacerX's I know for certain can do this. Just wack it wide open and it screams! However, change the ambient temp 20F and that's no longer the case, lol.

Most excellent! What's your setup? Is it similar to RacerX? Did you use a specific procedure to get to where you are?

P.S. To the OP: I didn't mean to steal your thread but it is still about carburetion. Hopefully it's helpful.

[Deathjunior]

Well I'm still tweaking it but I may have it fixed minus it still idling a little bit high. I guess my bike was getting to much fuel at 2.5 turns on the idle screws. Its never needed a choke on start up even once and the plugs were brownish black. Plus with the bike started up the choke was almost to much. So I started by lowering the idle screws down to 1.5 turns. That seemed to help because now when it died I could use the choke to bring the engine back to life so that meant that healthy a/f was somewhere less than 2.5 turns and above 1.5 turns.I have is at 1.75 turns at the moment and it seems better though I'll see how it is with the new slide vacuum when it shows up. I'm wondering if perhaps both the pilot air and fuel passages were clogged when i cleaned the carb and i just cleaned the fuel passages? Because it running pretty rich at 2.5 turns.

Also it needed that 110 jet, I'll work on washers if I need them later but it was sputtering like crazy with the stock jets and still sputtering on 108s. I may lower it down to a 108 in summer temps but in 75 degree weather it needs the 110 to even bother going past 8k rpm, once I know its happy at idle I'll do some more jet work with needle shimming.

Any suggestions on cleaning out the pilot air ports? Or are there any?

[spooph]

Originally Posted by MAZ 80

Most excellent! What's your setup? Is it similar to RacerX? Did you use a specific procedure to get to where you are?

P.S. To the OP: I didn't mean to steal your thread but it is still about carburetion. Hopefully it's helpful.

Nothing special, nor would it probably work for you. What I have discovered is that 20F change is worth about 1/4 turn on the off-idle. Going from summer to winter, 5,000ft to 10,000ft, I need to go from:

-38 pilot jet
-idle mix screw 1.25 turns out
-94 main jet
-clip on 4th space down

to:

-39 pilot jet
-idle mix screw 2.75 turns out
-98 main jet
-clip on 2nd space down

Constants:
-float level set to factory specs using the tube method (want to try this bench method as well as bench synching).
-airbox with massive hole cut in it.
-slipon
-stock headers
-valve cover block off plate
-counterbalancer disabled.

I really want to go to FI, but first, gotta massage that head - hopefully this winter (this will count 6 years officially of not getting anything done further on this bike). Grrrr.

Originally Posted by Deathjunior

Any suggestions on cleaning out the pilot air ports? Or are there any?

I use something like this: http://www.pjtool.com/20pcmicrodrill...xRQBoCtTPw_wcB

You can use piano wire also. You're best bet would be a heated ultrasonic cleaner with carb cleaner or something similar in it. That would get them super clean, but for now, the drill set will work.

NOTE: When using the drill set, don't drill the holes any bigger. I usually start with the wrong part of the drill bit - the back side, with no groves cut in it, to get a feel for what the passages/jets feel like. Only once I'm totally sure I have the right size drill will I put the sharp end in first...

on that note, I did drill out a set of stock idle jets to fine tune winter riding, that's how I got a "39" idle jet.

[Ghostt]

For PreGen, not sure about NewGen, but you can check with Kawasaki

High altitude adjustments require replacement of certain carburetor jets.

High Altitude Carburetor Specifications
Main Jet: #102
Pilot Jet: #35

After high altitude adjustments are performed. provide the customer with the Vehicle Emission Control lnfonnation Update Label and label installation instructions (P/N 99969-0614).

Advise the customer that by law, the Vehicle Emission Control lnforrnation Update Label must be affixed to any vehicle modified with the high altitude adjustments.

NOTE
If a vehicle with the high altitude adjustments is used below 4000 feet (1219meters), the update label must be removed and the original carburetor parts must be reinstalled.

As far as cleaning goes, did you remove the pilot adjustment screws? Did you remove all the jets, and main holders? Verify all the fuel circuits were clear with an air compressor? Assembled correctly? Most common mistakes are forgetting or improper installation of part # 16017, also the improper installation of the needles as well part # 16009, as in I've seen them installed rather than the top of the diaphragm, it's put thru the top of part # 16007. Also check the O-rings and small washer on the idle mixture screws, if these are damaged, worn, or missing, they need to be replaced, personally I use new ones with every rebuild I do, along with other parts.



And if I read correctly your trying to adjust with a bad diaphragm?

Note in the photo below the small orifices in the pilot jets, and main holders, these must be clear, just like the jets themselves, and are just as critical.


Most important is having the proper tools, replacement parts, and knowledge like myself and @ducatiman for instance.

[MAZ 80]

One more thing on using drill bits to clear holes. The shank isn't always as good as it appears at first glance. If it has any burrs or irregularities it can shear out that soft aluminum or brass. Inspect each one carefully.

[Deathjunior]

I've cleaned out all of those jets so that's good then. What are those silver tubes in the picture?

There's really not a whole lot of mods to the engine, replacement timing chain, valve adjustment, k and n pod filter, header wrapped exhaust which made a surprising difference in flow. But that's about it.

[ducatiman]

silver tubes are needle jets....16017 in the schematic.

you mean you didn't remove and clean the inner walls?

oy...bloody amateurs....

[jkv45]

Originally Posted by Deathjunior

I've cleaned out all of those jets so that's good then. What are those silver tubes in the picture?

There's really not a whole lot of mods to the engine, replacement timing chain, valve adjustment, k and n pod filter, header wrapped exhaust which made a surprising difference in flow. But that's about it.

Those are in-place - right?

Others have installed them incorrectly and had problems. If they are not there, or installed improperly, you have found your problem.

[ducatiman]

seen this on multiple forums, with many users...
if needle jets were not present....his complaint and classic symptom would have been..."starts, idles, but stalls/dies when throttled".

I'd suspect he never removed them at any time. But what the hell do I know?

OP?

[Deathjunior]

Yea I never removed them at any time I just pulled the parts and cleaned them when I went to drop my 110 jets in. I'm not sure what's up with it. If the valves themselves were bad could they cause this? I've got a spare cylinder head but I really didn't want to have to perform that kind of surgery. Ducatiman pm me on that carb so we can discuss terms I think I'm gonna call it quits.

[Deathjunior]

For anyone else who thinks they have any ideas now that I've been driving it I'll try and explain. The engine runs fine until it hits about 170 180 and even then its still fine if its just sitting. If I blip the throttle the rpms increase with the throttle but it will hang at 3k. When that happens I'll try and turn the idle screw down to an appropriate number. Then when I blip the throttle more than just a little it throttles up and the bike dies slowly whenever I let off the throttle its almost like the throttles just randomly sticking but it only does this at about 175° and up. So I'm not sure anymore. That new vacuum showed up but its defective to I've got to have another shipped to me. This is just really frustrating

[ducatiman]

Originally Posted by Deathjunior

Ducatiman pm me on that carb so we can discuss terms I think I'm gonna call it quits.

PM has been sent containing a few options, your input needed at this point.

[Deathjunior]

Well I rechecked valve adjustment for the third time and the problem is still continuing though the idle is stable now until the engine dies at about 175-185.

It was weird though I got the bike to idle just sitting there up to 185 this time and then I shut the engine off and it started right back up so I thought it was fixed. I took it for a ride up the street and it idled fine at the first light but by the third light after a long stent around 7-8000 rpm going 40 ish I let the throttle off and it died on me. I was able to get it started quickly with the choke and ride it to a parking lot where it idle at 2k then I put it in neutral throttles it up for a bit and watched the engine die. I should mention the temperature was down into the 40s. But its to much like my other issues for it to be a cold temperature issue.

Could one of my valves be just bad enough to cause this? If so I've got a spare cylinder head I can clean up and put on it but its a very long process to change it

[Ninjinsky]

Originally Posted by Deathjunior

Well I rechecked valve adjustment for the third time and the problem is still continuing though the idle is stable now until the engine dies at about 175-185.

It was weird though I got the bike to idle just sitting there up to 185 this time and then I shut the engine off and it started right back up so I thought it was fixed. I took it for a ride up the street and it idled fine at the first light but by the third light after a long stent around 7-8000 rpm going 40 ish I let the throttle off and it died on me. I was able to get it started quickly with the choke and ride it to a parking lot where it idle at 2k then I put it in neutral throttles it up for a bit and watched the engine die. I should mention the temperature was down into the 40s. But its to much like my other issues for it to be a cold temperature issue.

Could one of my valves be just bad enough to cause this? If so I've got a spare cylinder head I can clean up and put on it but its a very long process to change it

Mine was like that for years regardless of multiple carb cleanings and even a swapped carb set, valves checked ecu swapped and all the rest and always the same, It goes like stink, you think it is sorted, then it dies on you at some junction.
Everyone who has not had the problem thinks it's just a servicing issue (ultrasound the carbs, check the valves, change the plugs, air filter etc')
I sold it S or R a while back.

I'm not saying this to be discouraging, I love riding these bikes but in my experience you may have to draw a line under it and trade for another, sweet running, Ninjette before the carb problems suck years of your life away.
Like a bad marriage, getting out early is the key

[ducatiman]

^ depressing

retort: for every mechanical malfunction there lies a repair solution

[Deathjunior]

Well the throttle response seems better now with the valves adjusted again and it still liked the 110 jets. At this point it seems like the most likely culprits are bad valve seats, bad battery (mine is brand new)/coil packs(which are old).

Unless someone has suggestions because this is getting ridiculous

[Country Joe]

Originally Posted by ducatiman

^ depressing

retort: for every mechanical malfunction there lies a repair solution

True, true, true.

[Deathjunior]

Well I believe I fixed my issue with some new ignition coilds. However now I have a new one. I'm getting tired of these. It started up and ran it to 212 and everything was great started just fine. Idled well I shut it off and turned it over a few times. Now though it won't even try to start, its not a bad solenoid because it's not even clicking. So should assume bad relay or?

[Ghostt]

Could be your solenoid, quick test, take a screwdriver and touch both of the poles on top, if it cranks, then your buying a new one, if not, check battery, and connections, especially the grounds.

Do you have any power? If not check main fuse located on the solenoid.

[Deathjunior]

I figured it out an hour ago the clutch switch was messed up. Got that taken care of, it was sticking, I'm pretty sure the carb is running super rich on the pilot jet though because when it comes down from from throttle it hangs at 3k for a while plus the bikes idle slowly creeps up. I am forced to pull clutch lever to get it started, that's the nuetral switch that's bad. I'll take it for a ride in a few days , wish me luck

[ducatiman]

Originally Posted by Deathjunior

I figured it out an hour ago the clutch switch was messed up. Got that taken care of, it was sticking, I'm pretty sure the carb is running super rich on the pilot jet though because when it comes down from from throttle it hangs at 3k for a while plus the bikes idle slowly creeps up. I am forced to pull clutch lever to get it started, that's the nuetral switch that's bad. I'll take it for a ride in a few days , wish me luck

are we not back to the original issue...thread topic : idle increases drastically as it warms up?

[Deathjunior]

Yes but in the original post I mentioned the engine dies and won't start after a while. I thought the two were related. After putting in new ignition coils I believe I found the problem with the engine dieing and not restarting. So 1 issue done. I'm going to try and lean the pilot jets out to 2 turns and see what happens

[Ghostt]

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.**

[Deathjunior]

I took the bike for a ride and now the temperature it dies at is much higher 200+ degrees. I started the bike up at 150 not problem and let it idle for to 200 and it just shuts off as if its ran out of fuel. If i open the choke it tries to start a little bit and then fails. If it were a vacuum issue or an internal float issue would it cause this? Cause I'm pretty much down to carburetor or cylinder head at this point. With the new coils I think whats left is either time related in the carb or heat related in the engine.
I've got a spare head but it really sucks to change and if I go through all that effort and then find out that its carb then I waisted most of a day and 10-15 bucks on copper gasket spray.
On the other hand I can spend 165 on a rebuilt carb which will likely be a flawless part. Though if its a cylinder head/valve issue the carb won't fix it and I spent 165 and still have a to spend 10-15 bucks on gasket spray and a day of time....
Either way this sucks
I'm going to try and get the engine extremely hot try to check compression without burning myself and if

[22R88]

Had you sent the carbs to Ducatiman a week ago you would probably be riding right now..... You will get good at taking it apart and putting it back together though. Good Luck

22R88

[MAZ 80]

Pickup coils can do what you are describing. They get to a certain temperature and simply stop working. Try warming up the bike and at the same time, blast the area where the sensor is located. If it shuts off at a lower temperature, that could be your culprit.

Carbs and heads are usually not that sensitive to such specific heat related issues.

[MAZ 80]

One other thought. The temperature shutoff is coincidental and you actually are running out of gas. Try this. Warm it up and as soon as it dies, shut off the petcock. Drain the float bowls and make sure the full amount of gas comes out.

[Deathjunior]

MAZ, i hadnt thought of that at all but it makes sense. I'm going to test for that as soon as I have time. Way to think outside of the box that completely slipped my mind and it would make sense that better coils would raise the temperature at which it fails since better coils would offer less resistance.

22R88
I'm a poor college student man get angry at me all you like but I make 20k a year if I'm lucky. 8k of that goes to tuition the rest is rent, food, gas. I set asside 1100 for this project to get a motorcycle. I'm already over that. So yes you can bet I'm going to try and put in a 5 dollar part (which took that week to get here) that might fix it before I shell out 165. If this were a carburetor problem probably wouldn't be heat related.

So sorry if I spent a week waiting for an almost free part which by the way helped the bike run better and would have been needed anyway. You don't have to help and I'm happy for those that do. This site has been really great so far but playing captain hindsight doesn't help anyone.

[22R88]

Hey Buddy didn't mean to ruffle your feathers just trying to save ya some aggravation, but I understand where you are coming from and am glad that you are willing to dig into something and try to fix it and going to college. Best of luck and be safe.

22R88

[Ninjinsky]

Were you not in Missouri I would say you had bought my bike
One thing you might try is the rubber manifolds, they tend to harden with age (and soften with heat) so make sure they are snug, square and sealing well, it is easy to reach the point where you think you have screwed them tight but the clamps have run out of motion.

If it isn't that, how about (I'm playing devils advocate here) you cut a deal with ducatiman since there is an abundance of confidence , 50% to do the job and the other 50% if it works. not if it doesn't.

[Deathjunior]

Well it no longer dies just due to temp so the coils were the problem for that part I imagine. I ran the bike to a 215-225 degrees last night. However the throttle likes to hang around 3k no matter what I do, it eventually drops down but it takes a long while unless i rev it to a really high rpm then let off then its okay. However prolonged throttle and the bike dies when I let off, it seems to only happen when the bikes hot but the bikes going to be hot if I've been on the throttle for a while. So I think (i think, im not 100% sure because this could be a coupld of thins) this particular issue is float setting which is odd because i didn't change that or even touch my floats but it would explain my hanging idle as well as why it takes to long to restart after prolonged throttle

[Ninjinsky]

A stubborn fast idle can be, as I just suggested, a manifold air leak. Do check that both the carbs and engine end of these are nestled squarely into position.
This is a well known ninjette prob.
They are also oriented marked "Head" and "Carb" end, if one is reversed it will play havoc.
Loosen the clamps and nuzzle them around a bit to make sure they are snug in the "detent rings" and square. As they age they harden and get more difficult to deal with. Also the clamps may close completely and be unable to tighten the stiff rubber completely.

[Deathjunior]

I'll check the boots with some carb cleaner and see what happens though mine aren't cracked anywhere and they're seated just fine on both sides with no cracks in the boot but maybe. I don't think it would be the cause of the engine die when I let off prolonged throttle though

[jkv45]

Originally Posted by Deathjunior

Well it no longer dies just due to temp so the coils were the problem for that part I imagine. I ran the bike to a 215-225 degrees last night. However the throttle likes to hang around 3k no matter what I do, it eventually drops down but it takes a long while unless i rev it to a really high rpm then let off then its okay. However prolonged throttle and the bike dies when I let off, it seems to only happen when the bikes hot but the bikes going to be hot if I've been on the throttle for a while. So I think (i think, im not 100% sure because this could be a coupld of thins) this particular issue is float setting which is odd because i didn't change that or even touch my floats but it would explain my hanging idle as well as why it takes to long to restart after prolonged throttle

As Ninjinsky said, check for a vacuum leak.

From what you describe, it sounds like the throttle could be hanging-up for some reason - like a bad cable. I would also confirm that the carb slides are dropping smoothly.

[Ghostt]

Also make sure the diaphragms are installed properly.

[Deathjunior]

Just as an update, no its not fixed. I've just been really caught up with work, school, and my GTO has a rattling catalytic converter so now I have parts on the way to fix that, thank you amazon credit card cause I'm broke.

It runs at a much higher temperature before it dies now, and I don't have to open up the idle adjustment screw near as wide to get it restarted now. This is the results after swapping the coil packs. That leads me to think ECU or Stator, Sta tor would effect the engine dieing but it wouldn't effect the engine not starting after? The battery seems to have well over 13 volts when the engine dies and I've checked and rechecked the rockers.

I'd say it could be carburetor but I just can't see what in the carb would cause this. I'd say it could be the pickup but I got the engine to 212 degrees and the pickups resistance was easily in spec.

I was thinking stator or ECU since the replacement coils helped.

[jkv45]

Thanks for the update.

You did confirm there wasn't a vacuum leak anywhere, right?

A guy (with a different bike) on another forum was having similar issues, and eventually traced it to a vacuum leak that only became an issue when the engine got hot.

[greg737]

Deathjunior, First I want to say I like that you're willing to fight the fight with your EX250. This is how you learn stuff in the long term.

Calling the EX250's ignition control box (CDI) an "ECU" is giving it more credit than it deserves. The EX250's box is a "caveman banging rocks together to make fire" sort of thing when you compare it to a truly modern-day automotive/motorcycle ECU.

But you might be on to something with your speculation that the CDI might be the source of your cut-out problem. And I wonder if what you're interpreting as a heat related issue is actually more of a run time issue?

The electronic components inside the EX250's CDI box tending to have the shortest lifespan are the two little Transistors that ground the coils to fire the spark plugs. These transistors (to get all scientific: Silicon NPN Triple Diffused Planar Transistors) do the CDI's most difficult electrical work. The act of grounding the bike's ignition coils is a high energy activity so these transistors are always mounted to an aluminum heat sinking background plate.

Here's a picture of the insides of a classic EX250 CDI:http://i5.photobucket.com/albums/y16...m/P1120892.jpg. You can easily see the two ignition control transistors because they're mounted to aluminum heat sinks (the two components in the upper left-hand side of the picture). The yellow goo is meant to stabilize the capacitors in their mounting to the circuit board.

I mention all of this because of a situation with my other motorcycle, a '93 GSF400. The CDIs on these older bikes have become rather failure-prone with age, and the component that usually fails is one or both of the ignition transistors (additionally some of the CDI's capacitors also fail). I wonder if some of the EX250 CDIs are nearing the end of their natural lifespan. The problem with things like transistors and capacitors is that they can vary greatly in quality and durability. Your '05 EX250 CDI might be failing while another '05 CDI (maybe even most other '05 CDIs) might have years of good service left in it. Your CDI might be a "worst case" example of the group.

The good news: This would be an easy thing to test/diagnose. The EX250's CDI is easy to access and to remove/replace so you could get a spare CDI (even temporarily borrow one from another EX250 from the same age-group), plug it in and run the bike to see if things improve. Just be careful/gentle with the CDI plugs and wiring bundles because they're a decade old now and probably not as flexible as they used to be.

Good luck with the bike.

[Deathjunior]

-yes i tested for vacuum leaks with carb cleaner, as well as a more flamable parts cleaner (basically just a higher concentrated carb cleaner). I'm going to try with starter fluid to be sure

Only reason I'm thinking electrical is because the new coils helped run time and I don't have to turn open the idle screw near as wide to get it running when it does die so I figured might be just a weak spark when the engine gets hot.

If it still has a spark but its weak then it may take a larger quantity of fuel and air to get or to combust though once the engines running at higher rpms with the mixture being compressed at a faster rate and higher voltage from the battery the spark is enough as it is much easier to keep an engine running than it is to start it. Then when the engine comes down from high rpm to idle at a stop light the weak spark can't keep up with the rapid fuel/air loss.

This is all just do speculation. I was thinking stator but the battery wouldn't have such a hard high voltage and I know its not the pickup coil having tested resistance, so that leaves the CDI or as I called it an ECU, carburetor, or valve/cylinder head issues and I've redone the 4 times now.

On my valves 2 times I had redid the valves and somehow I lost a lock nut off an exhaust valve in cylinder 2, same rocker arm location each time though I used a new rocker arm. I know I torqued them to spec every time this last time tripIe checked the torque on them. I'm going to check the rockers again and make sure their good as well.

I've missed out on most of the riding season but at this point its a matter of principle I need to fix it

[Deathjunior]

Well I took the ninja out on the highway today to get it back to my house since I've been repairing it in a friends garage. Farthest distance I've ever taken it. So I started it up and rode it 3 miles, and I had to sit at a light for a bit. It idled just fine at the stop however I heard a noticeable rpm drope when it cracked over 185. I got it down the street and stopped at a gas station and then let it drop down to 120 and got on and tried taking it down the highway. Its an 8 miles stretch to the exit when I needed to get off. I got it up to 60 mph and 7000 rpm and the idle just slowly creeped up the whole way until I shut it off at the gas station at the exit at 235 degrees. The coolant wasn't boiling over but I imagine it would have been. But this engine should be running cold at those rpms it was 50 degrees out and 15 mph winds. So I'm thinking the engines been running hot and it just hates those high temperatures. From there any suggestions? I radiator is hot when I stop so coolant is flowing? Its not running lean? Either the rad is bad or the water pump is toast or atleast thats my guess.