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Hello!

Cleaned the ABS sensor didn't work, of course. I like it complicated.

I switched the front with the rear sensor trying to understand if the problem was the sensor or the ABS pump/ECU.

Switching the sensors did not brought any significant improvement, nor new problems. I expected to had the problem on the front but it was still the rear brake who had issues.

I put some shims under the sensor but it was rubbing against the disc so, in the end, I was looking to service the ABS pump but I first wanted to take a closer look to that phonic wheel (the serratic disc). It was slightly bent so I asked for the workshop chief help (the hummer) and put it straight. No more issues 

Now I think I need to service/replace the headset bearing because they have a strong point in the middle which makes the ride very unpleasant and dangerous.

Ride on!

Hello everybody!

Do we have a running engine here? YES, WE DO! 

Let me share the full story. I bought a new starter motor, very similar to the original... did it fix the issue? Of course not. But let's start from something I hadn't mentioned before.

As Ruffus wisely pointed out earlier in this thread about buying a used wiring harness:

[...]But be sure it's from the same year. There are sometimes small changes.

He was absolutely right. Here are the differences:


    Mine is the wide one (Euro3 spec)

    The one they sent me was for Euro4 spec

Had to return it, but I knew the electrical system wasn't the real problem since I eventually got spark.

The focus then shifted to the starter motor. Bought a new one, installed it - but engine speed while cranking remained the same, still not enough for spark. I decided to close the crankcase anyway (stator and coil were good) and tried starting the engine with a drill. That didn't work because the spark plug created too much compression for the drill to handle.

Then I remembered the new battery I bought months ago for this scooter (the type where you need to pour acid in). Installed it and... the cranking speed became incredibly fast, even with the spark plug installed!

This made me question: did I really need a new starter motor? I tested the old one again and confirmed it's at the end of its life - it couldn't turn fast enough to generate spark with the plug in, though it worked without the plug.

What really confused me was that I had done countless tests with car batteries (even with cars running) and never got the starter motor to reach sufficient speed for spark. I suspect my jumper cables were trash and couldn't deliver proper current. They drove me crazy!

Here's a video of the first successful engine start:
https://mega.nz/file/Kt1W2SQa#gQf5CzcMeDIZau8nxoO17c2O9NvzSfiw_-2KuCmK28M

Turns out I did need the new starter motor, but it had the positive terminal in a different position compared to the original. As you can hear in the video, I couldn't install the airbox because of this.


My solution was to take both starters apart and swap the internals of the new one into the old housing:


Later I discovered this wasn't even necessary - you can just loosen the two screws holding the starter together and rotate the cylinder slightly. Who knew!

But wait, there's more! After the first test ride, I noticed the ABS activates immediately when using the rear brake (doesn't happen with the front). Removing the ABS fuse returns the rear brake to normal operation (without ABS intervention).

Any suggestions? My first step will be cleaning the ABS sensor (which means removing the muffler again  ).

Thank you all for being part of this journey. I couldn't have done it without this community's help.

Hello everyone! 

We finally got it sorted, kinda 

The good news is that I managed to see the f****g spark on the plug!! I'm super happy, thank you Ruffus for your precious support!

The bad news is that maybe all the tests and parts bought were useless.

The problem seems to be on the rotation speed of the engine during the crank phase. In fact, in an enlightened moment I had the idea to use a drill at the maximum speed to rotate the engine through the flywheel nut, instead of using the starter motor.
Since I have bypassed EVERYTHING there was no need to press the brakes or press any switches. It immediately fired the spark at the spark plug! My mouth was wide open for a good minute, in silence and immobilized 

I think I'll keep the new stator, pickup and coil on, they are new and original and I see the replacement as part of a "preventive" maintenance.

More to come on the disassembly and inspection of the starter motor, all my guess are on it because I tried all kind of different combination of batteries (even with car idle) and never never got the engine to rotate at the right speed to fire the spark!

Sorry this message can be confusing, I first saw the spark friday but I'm still super excited! Thank you truly for the support! 

Hello! I didn't had the chance to work on the scoot lately, but I received an offer from an ebay seller for a complete electrical harness I had on my cart.

Do you think I should try it for 35€?

...scratching scalp🤔
 Tried to manually short the coil ground to the chassis and I can see the spark at the spark plug.

-means coil is loading and discharging, so it gets juice

Also, I took a look at the downtown service manual, which has dedicated pages to ABS ECU, but I didn't find any correlation between ABS and Ignition.

-don't think ABS is causing this in any relation

Last bit, which may be very important, is the TPS. It is illustrated in the ignition system diagram, why?
Could a bad TPS cause no spark?

-since we have to claw any last straw, yes, it could cause a malfunction
Try to change the sensor with a known good used one if possible.
Honestly I have to admit, I don't know, but still think we just missing something anyway clear piece malfunction like a cable, connector, plu, ect.

I had already did the coil test  with the CDI powering the coil and shorting it to the scoot ground and it sparks. The oscilloscope came but I didn't have the time to measure the signal yet!

Thanks for the confirmation about ABS 

My though is the same as yours, it is something very, super stupid. And yet... I'll do some other test!

Hello! Here's the update 

First of all, some pic of the tests. Tried to start with car in idle and benchtested all the relays (activation and continuity). I can hear them work if I short circuit the switches when the key is on, they are definitely working.

To answer all the questions I re-run all the tests again:
- brake switches are ok, otherwise the starter motor would not work.
- side stand switch, same story. Bypassed, otherwise no starter motor.
- fuses, all renewed.
- all groundpoints at the chassis, cleaned, tested continuity with chassis and their endpoints.
- killswitch bypassed, otherwise no starter motor.
- tilt/roll switch, disassembled completely, cleaned and tested. It gives in output 0.9V which is exactly in spec.
- didn't find the connector within tunnel, but tested each single wire in continuity from source to destination.
- pickup signal coming to the CDI connector is OK.
- power to the ignition coil is OK. Tried to manually short the coil ground to the chassis and I can see the spark at the spark plug.

What I can see is that the green/brown from CDI to the ignition coil, which should send the signal (put it to ground for a short instant when the pickup reads the magnet) is correctly connected to the CDI and receives some sort of signal, but no spark. Bought an oscilloscope!

Also, I took a look at the downtown service manual, which has dedicated pages to ABS ECU, but I didn't find any correlation between ABS and Ignition.

Last bit, which may be very important, is the TPS. It is illustrated in the ignition system diagram, why?
Could a bad TPS cause no spark?
The service manual says its resistance must be something from 3500 to 6500 ohms but mine is more about 1000 (fully closed) to 2000 (fully open) ohms.
It seems to work, because through the TPS I reset codes of the ECU multiple times.

What do you think about it?

Thanks 

Hello!
As Ruffus said, CDI are not likely to fail, in fact it is not the culprit!

I ordered a second hand CDI, contacted the seller he told me it was kept from a crashed scooter.
Even with the "new" CDI, I have no spark.

After all the test I did, I changed stator with pulser coil (new), coil (new), cable (new), spark cap (new) and spark plug (new), CDI.

I bypassed all switches (brakes, kill, side stand, roll sensor). I deleted codes on CDI but still no spark. Checked thousand times the continuity of each cable, and they are ok.

What I can see is that the ignition coil receives power but does not receive the trigger to spark!
How is this even possible?

P.S. Ruffus I gotta say that the coffee has to happen online, 'cause I live in the far south of Sicily 

The simple stator test is to slide a screwdriver along its magnets, each should be the same adhesion. Broken treads are nearly not to be seen.
Is it the correct pickup?
-reaches deep enough into?

Ignition coil test: put a weak (LED) 12V lamp on this two leading cables (coil mounted)
-starter, LED showing flicker?
-renew all fuses!
-cableshoes under fuses?
-sparkplug cable new?

Maybe it is not the correct pickup, because the resistance is slightly over spec, but it looks the same and its position is fixed, as the old one. Anyway I tested both with a led and they look like working, both of them.

Fuses have been cleaned and tested. Did not check the cableshoes under fuses but checked all the continuity and they are ok.

As per the ignition coil I put a led at the black and green/brown coming from CDI:
coil unplugged --> led ON (11,02V) with key in ON position.
coil plugged --> led OFF, even if cranking. It just blinks before switching key to OFF.

Black (from CDI to coil) with ground: 12.6V (battery voltage).

I'm going crazy here. I think I'll buy a new stator, pickup, CDI and ignition coil all new