Unfortunately the motor now sits on a dolly since i swapped a completely different make and model motor into the F4 frame. I tested spark at the head and frame when the motor was still in the bike. I used a multimeter to test all the wires for breaks. I even undid the factory tape on the harness to verify there were no burns or shorted wires.

I'm not a mechanic but I can usually sort this kind of crap out. I ended up installing a fuel injected 2005 gsxr 750 motor I had running on a stand. I just want to get this figured before I die or it gets tossed in the trash. 🤣

 

I cut my ignition wires cuz lost key so im having same issues do i need that diode to get spark regardless??

 

How do you put fuel in it with no key? Just get a replacement ignition switch/key off ebay.

 

Took on a cbr900rr that had the same problem, previous mechanic was just throwing new parts at it and gave up saying it needed a full new loom. I looked at the full schematic for the wiring diagram and tested everything and couldn't find a problem anywhere. I seen the resistor under the ignition but took no notice of it until I read this post. Resistance across it was all over the place and the pink wire was at 12v until I touched the resistor itself and the voltage kept changing, the resistor is broken but got it to hold 9v Temperley and all of a sudden I have spark again. Something so small would cause someone to sell/scrap a bike. A big thank you to you 👏👏

 

Thanks for the update and welcome to the forum.
That resistor is the cause of many problems with these bikes, esp when installing aftermarket ignitions onto them.

 

It's not a resister - it never was a resister - it's a DIODE. Its job is to reduce the battery voltage to 9v to trigger the ECU to understand the ignition switch has not been bypassed. It's an anti-theft measure.

 

Sorry, my bad, yes a zener diode!

 

Can it cause the bike to misfire at high revs under load? That's the problem I'm having now

 

if vibration is causing it to fail then I expect so - it will cause the ECU to crap out.

 

I have a new diode soldered in, 9 volts at the ecu but ignition cuts and misfires at high revs under load