HI all,
as from the introduction to the Forum, I'm Massimo from Italy, and I'm getting mad in modifying a 1991 K100 16V.
It's not my first Special, but this one is possessed by the Soul of Satana. 
Before I've started any modifications I tried the bike, and the engine started suddenly. 
So I started working. Unfortunately, since I'm from Naples but I work in Rome, I can work on the bike only in the weekends, so it took time.
After modifications, everything works well, except I have no spark at plugs. 

DIAGNOSTIC STEPS
* sidestand bypassed with a short circuit in the connector, 
* clutch switch bypassed with another short in the connector
* pump is working properly and turns well
* starter engine works well 
* gear connector is connected, Neutral light is working properly
* Put a 4W lamp on both coils primary, with no lamps. So the fault seems to seat in Hall sensors or ECU.
* Diagnostic says 1133, second hall sensor. I bought a second hall assy, with same problem and same diagnostic. 
* TPS diagnostic also failed, so I moved the sensor unless the diag was OK (Led on on closed throttle, off when opening).

MODIFICATIONS:
* removed the key key switch, and put a motogadget M-lock (linked the two gray wires together, and put the m-lock between green and red wires
* removed the left handlebar switch assy, connecting position light and low beam lamps together to make them always on
* removed the right handlebar switch assy, connecting together emergency switch cables to bypass switch
* modified the indicator lights relay, cutting the pin #7 track on printed circuit to disable fast flashing (I'm using Kellerman indicators)
* removed all the instruments, using  a motogadget mini with motogadget motosign mini, and a BEP 3.0 Control Unit to get all the signals from the bike. Everythng works fine

As I told before, everything seems OK but the bike won't start. Any ideas?
Every help will be greatly appreciated. 
Thanks in advance
P.s.: question: if I forget to connect the water sensor, the bike will start or issues in the water sensor will block the ignition?

If water temperature sensor is not connected bike thinks its overheated and will not start.....

You have messed with so many things including the instrument cluster, that your problem could be anywhere. Impossible to diagnose over the internet.

BobT wrote:You have messed with so many things including the instrument cluster, that your problem could be anywhere. Impossible to diagnose over the internet.

Hi Bob, you may be right, but I'm asking which components can lead the ECU in block. 
For example, as I understand, even if the TPS has a wrong setting and fail the test, the bike starts.

@Olaf: thanks for the feedback

another question: the key switch leads to a relay, or give power to the bike directly?
Thanks in advance

The temperature sensor will block the ECU if there is no signal, it interprets that as an overheated engine and does not allow the engine to start.

EUREKA!!!! Found it!
I don't know if you know the motogadget M-lock. It's a RFID device usually userd to substitute the ignition key.
It's a low power device. The kit come qith the RFID edvice and a relay. I used it on different bikes, sometimes with a control ECU like Motogadget M-Unit, sometimes as a replacement for the key.
The problem is simple. In the mounting, I didn't used the relay, b'se analyzing the slectric schema I found there's already an ignition relay. 
During the test there was no power loss or something similar, so I thougth everything is connected on that relay.
Unfortunately, it isn't so. The green cable of the ignition key switch is used to power the primary of the coils via the kill switch.
As already told, the M-lock is low power device, so all the measures on the coils are good (13V), but there's no power to sparks.

So putting the relay in will fix the issue.

The problem I live and work in Rome, but bike is in Naples, so I can work on it only on 1-2 weekend.

Maybe the moderators can change the title to something like "no spark to plugs after some modifications - M-Lock issue"


thanks for your help, I  don't know the bike, so I need to know the behavior (like no ignition if the water sensor is disconnected, or pump and starter engine stay off if kill switch is armed.