Dt125 RE DE06 no spark

[StallO.one]

Hi together.

I'm not getting a spark on my dt 125RE DE06 (2005).

So I was doing a short trip to a car dealer and everything was pretty normal. But when I wanted to return home the bike turned on normal but turned off directly. After 1h trying to start it again I finally made it home. During this hour it turned on every now and then but always died immediately. Approaching my house I decided to do some rounds between two roundabouts where everything appeared to be fine till it died directly in front of my house. When it died I was on the gas exiting the roundabout. So it died the last time with some revs like maybe 2000 - 3000.

After that I've checked and or exchanged several things:

First I checked and finally exchanged the spark plug. I tried a standard BR8ES and one iridium BR8EIX.

Then I checked the ignition coil and the spark plug cap. All seemed as described in the service manual. Then I ordered a new one.

After that I checked the interlock line, all switches the stator coil and the pickup. All readings from the multimeter in the tolerance described in the manual.

I found one pin bend in the plug from the kill switch and the red battery pin was also looking bad so I thoughts that's it and I bout a crimp tool and replaced the pins.

But guess what, still no spark. So I checked the rest of the harness and I found the harness coming from the CDI going under the seat being a bit flatted from the seat. So I thought that's the issue. So I took out the harness and checked each cable from continuity. But that was also fine so I also checked all wires with 3Amps of load measuring the voltage across to check for higher resistance. Still everything seemed fine.

Before buying a new CDI I decided to measure the outputs of the stator, pickup and the orange cable (CDI) against mass with an oscilloscope. The stator and pickup signals looked fine to me but maybe they are to low?

Pick up looks like one negative followed by a positive pulse with a 5v peak each (10vpp). The stator signal looks like Sinus with 30v peak (60vpp). Both were measured open with the plugs unplugged. The CDI output looked a bit off to me. A negative pulse cut off at -18V and some ripple with the stator sine frequency. More like spikes.

Does anyone know how it should be? I could provide the images of the measurements once I found out how to upload them.

The CDI signal looked bad enough to me to order a zeeltronic PCDI-10VT. But guess what. Still no spark.

So now I'm pretty much clueless what to check more. Any suggestions?

[Calum]

Oh that's frustrating.

There really isn't an awful lot to these engines. I've never heard of a stator go bad. I've had a bad ignition coil and I've had an aftermarket (bike sadly got stolen from me) ignition barrel disintegrate and cause this problem.

A common one is the side stand switch, similarly the neutral switch and the DTRE has the clutch switch.

Check the plugs from the ignition barrel to the wiring loom as they can have a tendency to trap water and destroy the connections.

Did you say whether the engine is healthy or not? Is it making a good PSI? Are the intake and exhaust pathways clear?

[StallO.one]

Hi, thanks for your reply. The side stand sw and the whole interlock chain should be good. I even bypassed all of that by grounding the blue yellow wire to the CDI directly.

The crimp contacts of the orange and black cable to the ignition coil is also new (forgot to mention).

I have nothing to measure the compession. But the engine was always making good power. Also just 1min before it died. I mean in the end is bad compression not preventing spark or am I mistaken?

Edit: Water issues could be excluded. I live in South Spain and if it rains two weeks per year that's a lot. And I never drive in wet conditions. I also never really wash it with lots of water.

The only other thing I realized ove the past year is that I needed the choke to start it more and more. But it was always perfectly running after 1min driving. So I thought it could be something like weak spark issue. Like something died over time till it's finally dead.

[Calum]

The side stand sw and the whole interlock chain should be good. I even bypassed all of that by grounding the blue yellow wire to the CDI directly

If I had to guess, that's probably your issue.

I see this time and time again with the side stand switch. My brother had a similar problem on his 2001 DTR many years ago now. My advice would be, if you're struggling to figure out a problem, get it as close to factory as possible, otherwise you're going to be chasing ghosts.

No a mechanically unhealthy engine wouldn't necessarily affect spark, but given how you described riding the bike and it cutting out, indicates that you had spark.

Okay, well it's good to know it's unlike to be water corrosion But still check those connections anyway to make sure they haven't vibrated themselves to pieces.

Ensuring good connection between that block is essential.

As I said previously, triple check the neutral switch, clutch switch as well. If they are vibrating loose they will cause intermittent problems.

[StallO.one]

Sorry, I think I didn't explain it well. The most times I tested for spark it was completely in factory condition. I tested each switch individually like two times and I checked all connections and replaced bad pins already. Then I just bypassed the interlock (only with the old CDI) as a last test to check if there is another issue since I didn't got any spark.

I also checked the schematics like 10 times to understand the interlock. And it basically just pulls the blue yellow cable to the CDI to ground or open and it locks or unlocks the starter motor via relay depending the switch conditions. The zeeltronic manual mentions stop switch mode: high level stop. So grounding it should bypass all switches for sure.

Regarding the mechanics I would also exclude that since it was running well and turned off like you hit the kill switch.

Two more things I just remembered:

I remember getting one or two times a single spark during all testing and if I remember correctly I was getting it in the moment when I released the starter button. So I thought maybe the starter motor or relay could cause issues like ground shift or something?

And with the old CDI I got a really tiny spark when I removed the spark plug cap then holding the wire close to the engine block. It was barely visible and I couldn't get one longer than 0.5 - 1mm. That was also a reason I decided to buy the zeeltronic. But I didn't want to test this again with the new CDI since they say clearly to use a resistor cap to prevent EMC issues.

[Calum]

Yeah okay, well that sounds like you've ruled out all most of the basic things.

I've had this before with a faulty ignition coil. These can still be bought brand new from Yamaha and I highly recommend going for genuine coil over an aftermarket one. The aftermarket one I had led me on a wild goose chase trying to figure out the intermittent fault.

You can measure the coil to see if it's within tolerance, what I was finding was that from cold it would work a treat, but once under load and warmed up, it would fail to fire above 4k RPM.

So it could be a worn out ignition coil, however unlikely that may seem.

Other than the stator/pickup, there really isn't a lot more to these engines to get them running.

[StallO.one]

For additional info: Here is the traces I captured (last one with old CDI). Pickup and source coil voltages look fine to me. Not sure about the Amplitude..

Pickup:

Source coil:

Output CDI (orange cable open to ground)

[StallO.one]

@Calum said:
You can measure the coil to see if it's within tolerance, what I was finding was that from cold it would work a treat, but once under load and warmed up, it would fail to fire above 4k RPM.

Okay good to know. So even my measurements looks okay to me I thought about that it might not be okay under load anymore. But I didn't want to manipulate any plugs just to measure under load.

@Calum said:
I've had this before with a faulty ignition coil. These can still be bought brand new from Yamaha and I highly recommend going for genuine coil over an aftermarket one. The aftermarket one I had led me on a wild goose chase trying to figure out the intermittent faul

Do you have any link or shop? Thanks