Okay so I have a 1987 k100rs I have turned into a cafe racer. The bike has only 30k miles and I am having a load of issues. Went to start the bike today and nothing... I click the starter it does a quick jolt of the starter then cuts out.. immediately I think it's the hall sensor.. nope hall sensor checks out fine... all of my fuses are good.. all connections and electric grease on them.. as I was trying to get it to start the ignition coils started to buzz almost as if they got stuck or something.. I unplug the coils from the harness and bam! The bike constantly turns over but no fuel pump.. strange... I check the pump with a 12v jumper it works I then go to the under tank connection and I am getting 8volts with the starter depressed and it jumps to 10volts for 1.5 seconds after starter is let go... changed out FI relay.. nothing.. cleaned the starter winding and brushes.. nothing... swapped the load shed and light relay and the light still works.. only 8-9volts at number 6 fuse.. their is continuity from the computer to the FI relay but it is always at 0volts  and does not carry 12volts with the ignition on.. do i need a new computer?? Anything I'm missing? Sorry for the long post I wanted to be thorough

Edit*** just to clarify. With the kill switch in the run position and the key in the on position their is no 12v from pin #7 to the FI relay and when i press the starter their is not change in line voltage (should be +12volts when when key on and grounded when starter is engaged) let me know if I'm wrong thanks again!!!

53cr3t5quirr31 wrote:Edit*** just to clarify. With the kill switch in the run position and the key in the on position their is no 12v from pin #7 . . .

Pin #7 of the ignition control unit, pin #7 of the fuel injection control unit or some other pin #7?

Pin #7 of the ignition control unit

Okay guys update****
I checked the wrong pin :/ I have now checked the correct pin #7 (not #2 as previously) and I am getting 8.8 volts with all the switches in the on position... when I go to crank the bike it drops down to 6 volts...
Also when I plug the coils back into the harness it's still only blips the starter before cutting out...
Dead CDI??? What's your thoughts?

53cr3t5quirr31 wrote: What's your thoughts?

What is the resting voltage of your battery right now?

12.6 volts

*update
I just checked pin #10 at the ICU and I only have 9.4 volts

Sounds like a bad battery to me.

12.6V sounds like a weak battery/one that won't hold a charge.

I'm running it off a large jump pack so I don't bleed down my brand new yuasa. All other fuses have 12 volts except fuse #6 it has around 8-9

Firstly I would recommend replacing all the fuses. They get some internal corrosion and will fail when they look OK.

Already did that every fuse is brand new less than a week old

The next step is to systematically go back along the wiring path and check voltage at each junction. My first place to suspect is the blue green wire at the ignition switch then the kill switch Green/yellow wire. I will say that a bad connection is responsible for the voltage drop.
The ICU and ECU will only work if the voltage is over a predetermined voltage of (I think) 9.5Volts, but it is in the area of the voltage you are finding.

Okay I'll check for breaks in the wire. I believe the CDI is powered on because it triggered the FI relay and that is controlled by the CDI
Will report back

RicK G wrote:blue wire at the ignition switch

What blue wire?

Every ignition switch I've seen only has:
Red
Green
Gray
Gray/Blue