Older CDI on 09' 250r -- only sparking on one cylinder

[corksil]

Long story short I ordered a used older CDI for the more aggressive ignition timing. I hooked it all up, matching the six matching wire colors. There are 7 wires on the older CDI, and 8 on the wiring harness.

Brown/Black (bike side) was connected to Red (igniter side) on the older CDI.

Gray (bike side) was left disconnected and insulated.

Tried to start bike, would start and only run on right cylinder. Revving engine higher would not cause the left cylinder to "catch" and fire as typical with carb/fueling issues.

Tested continuity through all wires, everything was good. As far as I can tell, nothing was shorted.

Tachometer was not working even when the bike was running on one cylinder. Both coils tested within spec and I swapped the right coil (sparking) to the left cylinder and vice versa. Both coils sparked when connected to right cylinder. Neither coil sparked when connected to left cylinder. Tach output is taken from left cylinder (non-sparking) coil. I believe that explains why tach was not working.

Unless I'm mistaken, the CDI opens and closes either +ve or -ve wire to the coil to cause coil to spark. One coil trigger wire is green, the other coil trigger wire is black. I had continuity through black and green wires (independently of each other) back to the CDI.

I reconnected the 09' original CDI and the bike fired right up on both cylinders. I disconnected and reconnected the older CDI and bike would only fire and run on the right cylinder.

Is all of this conclusive evidence that the used older CDI I purchased is faulty? Seems pretty clear to me.. but I could be mistaken.

May be worth mentioning that the gray wire (bike side) tested battery voltage. With gray wire disconnected from 09' CDI, bike would not start. Once gray wire was connected to 09' CDI, bike would fire right up and run fine.

Please help. Thanks.

[corksil]

C'mon I'm sure someone knows about this.

[CrazyCanuckGoat]

The one I used was out of an 06/07. There is a thread on here with the diagrams for the wiring that I follow. I had no issues and bike fired up as per normal. I don't recall messing with the kick stand switch.

If you are sure you wired everything correctly, then yes, it sounds like you did get a dud CDI.

[corksil]

The ebay seller of the CDI offered to refund me if I mail it back to him.. But he mentioned that it's not typical for a CDI to only fail on one coil.

Anything is possible with electrical stuff -- but that is not good to hear from him. If I mail back the CDI and get a refund, I'll buy another used one but if they same thing happens I'm right back here to the exact same problem.

The only other thing in the electrical coil circuit that is not working is the tachometer which wasn't showing any signs of failure or malfunction prior to this.

Like I said, I swapped the coils and both were functioning when connected to the right side of the bike (green and red wires to coil).

I don't think there's anything else on that right coil circuit -- just the CDI and coil.

On the left side which is not working, the red comes from the CDI, and the black comes from the CDI but also goes onward toward the tachometer which takes its signal from the black.

Someone who knows about this electrical system could tell me exactly what my problem is.... Anyone? Really need to get this bike working because fuel and tire expense for my work vehicle killing me financially.

[choneofakind]

Hey, curious on this, Corky:

I'm putting a newgen motor in my pregen, keeping all else equal, which is kind of the same thing you're accomplishing since my bike is a '99. Do you have a link to instructions you've followed? I know there's something around here somewhere but I don't remember where.

I need to go study the wiring diagrams as a part of this. Any differences between the stators on the two bikes that I need to be aware of? I know the newer stator allows for more overhead on the newer bike, but that's all I know.

[genosr1]

put your pre gen jgnition parts in the new gen motor, easy peasy

[corksil]

Originally Posted by choneofakind

Hey, curious on this, Corky:

I'm putting a newgen motor in my pregen, keeping all else equal, which is kind of the same thing you're accomplishing since my bike is a '99. Do you have a link to instructions you've followed? I know there's something around here somewhere but I don't remember where.

I need to go study the wiring diagrams as a part of this. Any differences between the stators on the two bikes that I need to be aware of? I know the newer stator allows for more overhead on the newer bike, but that's all I know.

I don't know what to tell you. I have never done that swap before. All the wire colors for the igniter were the same except for the one I mentioned in original post -- brown/black connected to red on older igniter, and gray had 12v and was left capped off with heat shrink. Either way my bike still isn't running and I'm still not sure I have a bad igniter so I can't confirm that it will all work when you hook it up like so.

Originally Posted by genosr1

put your pre gen jgnition parts in the new gen motor, easy peasy

This is probably the solution.

[corksil]

I'm bumping this thread because I've been busy with other projects but now I'm back to this one.

I'm right back at the same spot I was when I made the original post -- and I need to figure out what's going on.

If I turn the ignition on and disconnect the black wire from the left coil (same wire which sends signal to the tach) -- and then I reconnect the black wire to the left coil, the tach needle jumps. 30k miles ago I bought this bike with a non-working/erractic tach, and went through all kinds of threads trying to diagnose the problem. I clearly remember someone saying that a "tachometer test" was to do what I just described. I think it was also in the clymer manual. The "test" is to disconnect black wire from left coil, and then touch it to the terminal and see if the tach needle jumps. Mine DOES which makes me think there is nothing wrong with my tachometer. When I bought the bike with non-working tach, I tried the same test and the tach needle didn't jump. I replaced the entire gauge cluster with a used one and I've had no problems with anything since then.

Basically what all of it means is that all signs point to receiving a faulty used CDI which only causes the bike to spark on the right cylinder.

It would take all of ten minutes for someone knowledgeable to read through this thread and add weigh in on what they think the problem is.

I don't want to send my used CDI back to the ebay seller until I am sure that it is the problem. If I mail it back, get refunded, buy another used CDI and install it only to find that I have the same problem -- I'm really going to feel like an idiot and I'll be right back here again after wasting a lot of time and shipping a working part 4000 miles across the pacific ocean back to the seller.
@g21-30 @Racer x @HKr1 @kkim @bruce71198 @Somchai

C'mon guys... I know most of you aren't around the forums these days but I'm still hoping..

[Flying]

Has there been changes made to the wiring loom within the EX250F generation? Maybe the wires' colors have changed.

[Racer x]

First question is what year old cdi did you get? 88-94 is different than 95 and up.

The older cdi is very reliable. Better than the new one. And I think they work or don't But anything is possible.

[corksil]

Item description says 1990 EX250.

Which CDI am I looking for?

Thanks for helping Eric.

[Racer x]

88-94 was the original one I did the swap with. From my experience and I'm not 100 % sure. But I think all the colors are the same for every year. the problem is they change the pin location. Originally I bought a wiring harnes and just traced the wires.

How did you do the wiring?

[Racer x]

This is the pinout on my 08 with an 88 wiring harness

[corksil]

I reaaaally doubt that I wired it wrong. All wire colors were the same as described in original post with the exception of brown/black (bike side) which I wired to red (on new/older igniter.)

Then there was the gray wire which I left disconnected.

What's weird is the bike fires right up and only runs on one cylinder. I swapped coils left and right, and both coils work on right side. The coil connected to left side gets warm, as if energized, but it won't spark on that side.

I've heard that igniters typical fail on both cylinders, not just one. That's not what I'm experiencing and this is frustrating.

Maybe I could put a test light on the black wire (which triggers left coil) and crank the bike with starter to see if light blinks. If test light blinks, and same test on the right coil trigger wire causes light to blink, that means I have something else going on.

It's my understanding that the green wire energizes coils on both sides, and the red wire on right coil triggers spark, and the black wire on left coil triggers spark but also goes onward to give the tach it's signal to display on the gauge.

[corksil]

Either way I really appreciate the help.

[Racer x]

This is a good one. The answer will come.

I am thinking it's a simple thing that is well hidden. Did you check continuity through all the wires? Go back to basics and check each wire for a break and short to ground and short to Battery plus. Just for the sake of testing it. Eliminate all possible problems and what ever is left is the answer.

[bruce71198]

I got nothin for ya except the black wire should go to the - side of the left coil and the CDI box should toggle that circuit to ground. You can test this with a test light but it should be an LED test light. This circuit also sends a signal to the tach. I doubt the tach is pulling this circuit down but you might unplug it and see if it makes a difference. Also switch the 2 wires on the left coil in case you have them hooked up backwards, it should run both ways but who knows.I personally feel you have a bad CDI box.

[corksil]

Yep. Bad CDI. I just rechecked and retested everything.

Hook up 2009 CDI -- spark on both cylinder

Hook up ebay CDI -- no spark on left cylinder, all testing points to bad CDI.

Thanks guys, this one is a wrap. Mailing it back to the seller tomorrow morning and ordering another used one.

So the 88-94 CDI is the one I'm looking for, correct?

Bike is 2009 and I'm looking for the older CDI with more aggressive timing.

Thank you all. Very much.

[corksil]

Yep. Bad CDI. I just rechecked and retested everything.

Hook up 2009 CDI -- spark on both cylinder

Hook up ebay CDI -- no spark on left cylinder, all testing points to bad CDI.

Thanks guys, this one is a wrap. Mailing it back to the seller tomorrow morning and ordering another used one.

So the 88-94 CDI is the one I'm looking for, correct?

Bike is 2009 and I'm looking for the older CDI with more aggressive timing.

Thank you all. Very much.

[Flying]

Any CDI from 2007 and before will serve your purpose, the 88-94 ones will have a slightly higher redline. Make sure to avoid getting the california spec cdi.

[corksil]

Okay well here I am again following up.

Ordered another CDI, it arrived, I installed it. Bike fired up instantly, no choke.

It is my understanding that high humidity and wet weather make a bike run richer due to more water vapor in the air, which displaces oxygen molecules -- this means the bike runs richer because it takes equal parts air/fuel for the combustion event, and if there is less available "air/oxygen" due to higher humdity, less of the fuel is burned and the unburned fuel exits the tailpipe. I could be a little wrong on the specifics but that is my understanding. Wet weather = bike runs richer. Hot dry weather = bike runs leaner.

I chose today to install and test the older 87' CDI because I'm wary of a lean condition causing engine damage due to a lean mixture. Wet weather = bike running richer to slightly offset the more aggressive timing advance.

The bike ran with more power than ever before with the new/older CDI. The throttle response was more 'crisp' -- with the ninja 250 you typically whack the throttle open all the way and wait for the engine to get up near redline where it really takes off. The new/older CDI made the throttle much more responsive. A tiny throttle increase would translate directly to increased acceleration. Not as much "WOT and wait."

With the ported and polished head job, the race cams, and manual chain tensioner running a little tighter on the timing chain than the OEM tensioner, the bike screams. Given, I'm running a full race exhaust, pod intake, massive jet increases over OEM, and shimmed needles as well, this bike is now the most powerful as it has ever been in it's 32k miles of my use.

Also, the rev limiter seems to be on vacation, as I took the engine up beyond 17k and it was still pulling very hard before I upshifted.

One final note is that dropping the kickstand in any gear kills the engine. It used to be that I could start the bike in neutral with kickstand down but that is no longer the case.

Sometimes I wonder if manufacturers like kawasaki leave little 'easter eggs' to be found in modding their machines. With the older CDI this bike now runs like it "should" instead of some neutered emissions compliant whiny little b!tch bike.





The only way I'm going to get this machine to go any faster is with nitrous, forced induction, or higher compression and leaded race fuel. I have finally reached the "limit" of it's potential on pump gas.

Time to buy a bigger bike or keep tinkering. Who knows what will happen next.

Thank you all for your help in diagnosing my issue.

[Flying]

a leaner (not richer, whoops) fuel mix is needed to compensate for water vapor because:
- h2o not only displaces o2, but also n2 and fuel
- more o2/n2 in the mix will be displaced by water vapor than fuel
- water's high specific heat will make it soak up quite a bit of energy before you get the same work out of it than n2/co2

basically, you're increasing the octane of your fuel mix while using less gas. so run more air or increase the compression ratio and get the combustion chamber slightly hotter to get more efficiency. however, the definite path to more power is to increase the density of your mix




go blow-through

[Triple Jim]

Originally Posted by corksil

Also, the rev limiter seems to be on vacation, as I took the engine up beyond 17k and it was still pulling very hard before I upshifted.

Not sure what tach you're running, but maybe it's the one on vacation. I've had my share of miscalibrated tachometers.

[choneofakind]

^^^ This.

Rumor from others in the know is that the valve train is good up to mid-16,000 range. The odds of you suddenly running it to 17,000's isn't high.


But I bet it would be fun to watch the tach climb that high. powahhhh!!

[corksil]

^^ yep, I've got another tach sourced and it will be hooked up tomorrow or as soon as I find the time.. A stand alone unit which won't interfere with the bike wiring.

Also on order is a proper AFR sniffer so I can get some AFR numbers and really know what is going on in there.

Projects and more projects.. Bypassing the kickstand switch is also on the list of things to do..

[choneofakind]

Sounds like you got it all worked out. I'll keep referring back to this thread and maybe reference you with wiring if needed because I've yet to start sticking that newgen engine into my frame. I've been lazy and preoccupied with other things.

[greg737]

Also on order is a proper AFR sniffer so I can get some AFR numbers and really know what is going on in there.

You mean a wide band O2 sensor + controller? My favorite is the Innovate Motorsports LC-2. I've used Innovate wide band O2 controllers on both my fuel injection project bikes ('05 EX250 and '93 GSF400).