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Discussion Starter #1 (Edited)
I have read my fair share of stator, CDI and coil problems that cause a no spark situation on this forum, I feel that I may shed some light on this dark subject with the best of my knowledge on a dedicated thread, it's work intensive to help and write all this stuff everytime.
Following the manual gives a pretty good method using peak voltage hold multimeter, but most people have regular MM at best, it makes it near impossible to find a problem that we can't see without tools that can "see".
I'm using a scope for signal that have a pulsing nature, I have a Syscomp Circuitgear, it's a cheap open source USB scope.
While I was doing work on my quad I took some time to measure all the signals required for the CDI to generate spark, I will not cover the other ignition switchs.
The stator is composed of 3 circuits of 5 serial coils that send AC voltage to the regulator/rectifier to generate electrical power, with those there is two different coils, they are the exciter coils.
There is one wire before (white), one wire between the two coils(Blue) and the last is after the two serial coils (Black/red), so between white and blue we measure the low circuit that probably feed the ECU, between the same white and Black/red wire we measure the high exciter coil, this one is definitely charging the capacitor in the CDI in preparation for the spark.
So let's measure the low circuit, there is a gray plug by the coolant reservoir cap, it can be measured from the CDI 6P connector to make sure there is no wiring fault between the gray connector and CDI plug, the wires color are the same.





So I hook up the negative side of my probe to the white wire and the positive lead to the Blue wire, then I hit the starter and take a screen shot




So we can see how this pulsed voltage looks, I have recorded a peak value of 21,61V, the manual call for a minimum value of 15V, so it pass (must be a minimum of 30V for the 04/05 models)

Now for the high exciter coil circuit, so I keep my negative on the the white wire and move my positive lead to the Black/red wire



Now I have a higher value of 41,68, the manual calls for 45V as a minimum, close call, but I had 60 and 75V before I took my screenshot, so it's good !! (Must be 80V min for 04/05)


Now the pulse generator, this is the eye of the CDI, it sense where the crank is and will trigger the energy stored in the capacitor from the exciter coil trough a transistor gate.
The exact how is unknown at least to me, so if others want to share wisdom on the CDI blueprints I'll be more than happy. But on some CDI the pulse can trigger spark without the advance computer, then the computer takes over and (steal) the spark by triggering the gate earlier (spark advance), of course a kicker engine can't pass on the first spark before the computer recieve power and know RPM

Now let's get the pulse gen plug that is under the gray plug



So I hook up the negative to the green wire and the positive lead to the Blue/Yellow wire, crank the engine and take a screenshot...



I measure 5,21V peak and the manual calls for 0,7V minimum, this one is great
On a side note, you can see the small tooth and the big tooth on the graph, the rapid rise of the voltage on the small tooth is where the ECU reads the crank position because it's the only thing stable while RPM increase, all else stretch but the instant rise will be at the same place and precise.
On another side note they can also be measured on the 8P CDI plug Blue/yellow positive and 6P CDI plug Green/White negative


Now let's move to the coil, we are going to check if the CDI has any output at all, to measure this I had to make a 6x voltage divider, it's simply a 1000 ohms resistor and two 10k (to equal 5Kohms) soldered together, by applying voltage trough the 5k and 1k resistors, the value between them is equal 1/6 of the CDI value, I have done this because the high voltage would break my scope, I just have to multiply by 6 the results.



So I unplug the coil lead that is a Black/Yellow wire, so I hook up the positive lead to it and the negative to the frame, then I turn the kill switch on, crank the engine and take a screenshot



See that huge negative drop, well you guessed it, it's spark, so I measure -29,66V remember my 6X voltage divider, then -29,66 x 6 = -178V, manual call for 100V minimum.
Note that those who have found a peak hold multimeter should reverse the polarity, to get a maximum reading the peak must be positive so the CDI black/Yellow become the negative and the frame the positive lead, I have done it this way to show what is really sent to the coil.

So if the coil is trigerred it must output something.



Yes it is !! Some sparks are riding on the ceramic, it's an old BMW plug, but we get the picture.

Not everyone have a scope or a peak hold multimeter, but these are the most reliable ways to look for spark problems, there is an unreliable way to check at least the exciter coil continuity, it's to measure their resistance with a standard Multimeter
The low exciter coil measured 7,7 ohms and the High circuit 34,2, a much lower reading or much higher is indicating trouble.





For the coil a multimeter on AC mode will output something, not an usable value but someone could know if the CDI is dead flat or not.

A dead CDI may come from the throttle switch, the thumb switch must conduct when depressed not at closed position, if it do not conduct with the throttle depressed, the CDI will shut spark, this can be checked on the first CDI connector (4P by the famous green wire), measure resistance between engine and Gray/red wire, throttle closed = infinite or high resistance, throttle opened = close to 0 ohms. A tight throttle cable can cause this.
Also the ignition can be cut trough the main switch (conduct) and kill switch (conduct), this can be checked on the 6 Pins (last) CDI connector, measure the resistance between the engine and the Blue/White wire, there must be infinite or high resistance with the main switch ON and kill switch ON

I hope that this will help to keep you riding and help to understand the ignition electrical better
Feel free to comment and correct possible mistakes
 

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You sir are a fine man. Thanks for the good deed and hopefully this becomes a sticky. People like you are why society stands a chance.
 

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Discussion Starter #4
Thanks a lot, I dig so much informations off forums and informative posts from others so I like to give it back sometimes when I have the time to do so.
 

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Discussion Starter #6 (Edited)
High RPM miss

This post has been edited, because the information contained in it was not exact, it happened that I had two fuel problems that hapened at the same RPM fooling me into thinking it was an electrical problem.

So I have tested the exciter coil circuit with the engine running, there was a drop in voltage short circuit style that may be caused by the CDI firing at upper RPM, since I don't have the exact CDI blueprints it's a blind shot. I have finally proved that there was no misfires, I have cut up a perfectly running stator and rewound it for nothing, cost me 5$ and 4 hours. Good experience tough ;)



I have made a plug bypass to run the engine and take measurements off the exciter coil circuit, I have hooked up both chanels of my scope. The blue is the low circuit, the red line is the high circuit.
Here's a scope screenshot of the stator state at 4k



Now here's the upper RPM range , we can see completely missing low circuit signal sometimes twice in row and a drop of the hi circuit, it cause no loss of spark, may be from the CDI firing.


 

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Discussion Starter #7
I blew my own stator this week end, so I had to troubleshoot my own quad, easy right ?!?!!
First I have my own DIY DVA adapter, the first thing I have checked is what the coil is recieving, 36 V peak...well this is way too low to fire up, with my 24V starter I was measuring 295V before.
So I disconnect the stator and chect the peak volts expecting to get low figures...not !! Reads fine.
I measure at the CDI plug in and out, same. Is the CDI shot ?? Well I had overheating problerms, maybe the fan motor blew up and overheated the fan driver leading to CDI failure ??
So I replace the CDI from my 2008 quad, no joy 36V
Then I have seen the light, maybe a nice carbon track is shorting the coil to ground... bingo !! While I sould have measured infinite resistance to the engine block, I had 28 ohms to blue 68 to black, way enough to waste the coil energy to the ground before it reaches the CDI.

I had to troubleshoot another, different failure mode, resistance measured fine, but while cranking I had 0V to the coil in and a rising voltage at the exciter coil and it shorted internally when enough volts applied to the coil flattening the capacitor of my tester to 0V before reaching peak value.

My stator failure followed an overheating event, cracked rad and finished race (4th not too bad for a shot engine)
 

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Ok, I read you post and love how you took the time to do this.

I have an 07 and cannot figure out what exactly is wrong ,no spark . So far I checked voltage to coil and it's only .4v. So I bought a shop manual and followed thru testing exciter ring (stator) . Hi or low it fluctuates so much I don't get a voltage reading. So I pulled off side cover and cleaned flywheel with clean dry rag. Lastly I ohm-ed out pickup coil 241ohms. Opon further reading in shop manual it says basically replace parts in trouble shooting section. I want proof before dropping $200 on a stator and according to manual it could be Cdi or something else. Very frustrated. I accidentally jumped dead battery and blew fuse. I crossed connections with battery jump box, ya I may have caused the problem or it's coincidence. Please somebody help me figure this out. Thanks
 

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Discussion Starter #9
I had my share of ignition problems this year, I blew my second stator, but at least I have a model of how it happens.
Both of my stators blew the same way, an OEM unit and my DIY rewound.
The High coils are cooked medium well, it showed up as a short to ground, low resistance to the armature, coil resistance is in spec, but the insulation have started to peel off the copper, leaving a way for metal particles or carbon tracks to form a low resistance channel to ground discharging the ignition energy to ground.


First engine overheated and lost half it's oil, second engine didn't overheat, but ran hot for an extended period of time and oil is going to tranny side, leaving the engine side half full after a race.
It's running at 220 deg F already, then you have the power stator that heats the armature and the ignition coils that seem to produce a whole lot of heat, why not sure, but judging by the color of the varnish over the copper wire I have removed, it gets pretty hot and the heat have no where to go.
I think that some oil gets inside the flywheel and splash around on the stator poles cooling them off, but when the level drops below the flywheel, the occasional splash get centrifuged by the FW and heat is building inside the coil.
So I think that low oil level may be the biggest stator killer, aggravated by low speeds, clogged rads and long duty.
 

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Discussion Starter #10 (Edited)
Ok, I read you post and love how you took the time to do this.

I have an 07 and cannot figure out what exactly is wrong ,no spark . So far I checked voltage to coil and it's only .4v. So I bought a shop manual and followed thru testing exciter ring (stator) . Hi or low it fluctuates so much I don't get a voltage reading. So I pulled off side cover and cleaned flywheel with clean dry rag. Lastly I ohm-ed out pickup coil 241ohms. Opon further reading in shop manual it says basically replace parts in trouble shooting section. I want proof before dropping $200 on a stator and according to manual it could be Cdi or something else. Very frustrated. I accidentally jumped dead battery and blew fuse. I crossed connections with battery jump box, ya I may have caused the problem or it's coincidence. Please somebody help me figure this out. Thanks
Reversing the poles will most likely just blow the fuse, but if you had to jump start it you already had a failed ignition, right ?? First you will remove the left fender, unplug the green connector and short circuit the green 2 pin plug CDI side, I use an alligator clip for this.
If still no spark, take a multimeter set at OHMS, unplug the stator 5 pin grey plug, test resistance on white to blue, should be 7 ohms, blue to Black/red should be 34, then all of them to ground, should be infinite or megaohms or OL
I made some DIY stators testers (DVA adapters), they really shine to tell the CDI output, should be 200V plus, you can't measure it with a multimeter, it will just bounce all over the place.

www.trx450r.org/forum/93-engine/342586-diy-stator-cdi-peak-voltage-tester-adapter.html
 

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Reversing the poles will most likely just blow the fuse, but if you had to jump start it you already had a failed ignition, right ?? First you will remove the left fender, unplug the green connector and short circuit the green 2 pin plug CDI side, I use an alligator clip for this.
If still no spark, take a multimeter set at OHMS, unplug the stator 5 pin grey plug, test resistance on white to blue, should be 7 ohms, blue to Black/red should be 34, then all of them to ground, should be infinite or megaohms or OL
I made some DIY stators testers (DVA adapters), they really shine to tell the CDI output, should be 200V plus, you can't measure it with a multimeter, it will just bounce all over the place.

www.trx450r.org/forum/93-engine/342586-diy-stator-cdi-peak-voltage-tester-adapter.html
Thank you for the reply, I jumped it due to dead battery. It ran 3 days ago with a jump.
Why short circuit green connector? Says nothing about that in shop manual. Now I have new battery installed.

Also if pickup is bad can it be replaced with the one offered on eBay for $20? It says 04-05 but looks identical. I had seller ohm it out. Read 275 ohms , mines 241 ohms. I know I know I'm jumping ahead but have read that pickup is the problem not stator.
 

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Discussion Starter #12
Why short circuit green connector?
Disable ignition safety shutdown, most common no spark cause on 06+



Also if pickup is bad can it be replaced with the one offered on eBay for $20? It says 04-05 but looks identical. I had seller ohm it out. Read 275 ohms , mines 241 ohms. I know I know I'm jumping ahead but have read that pickup is the problem not stator.
Pulse generators and not known to fail, 241 ohms is fine, the high exciter coil is the part that plague us.

Try the basics first.
 

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Okay i checked those circuits and I got 8 ohms and 28 ohms. Not 7 and 34. I'm guessing the stator is ok?? I did not short out green connector yet as I was unsure if he should be on or off?
 

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Discussion Starter #20
Then you can build my DIY DVA adapter, cost a few bucks to make or find a peak hold multimeter you need to check the stator peak output and the CDI peak output
 
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