No Spark - v50 III rebuild

[Andy B]

Hi Guys,

I'm at a total loss to this problem at the moment... finally got back to being able to do a bit to the Guzzi after a short hiatus (girlfriend got a Ducati and so attention was focused on that for the past few months) , and I cant pass this hurdle...

I've been re-wiring the bike as i got it in a bit of a state... I've got everything back to as it should be looking at the wiring diagrams i found on thisoldtractor, and put some modern jap switches on the handlebars..

now, I turn the key, get dash lights, push the start button and it cranks but i dont have a spark... ??? ???

It's been suggested to me to short the kill switch wires and try again - no change...

the bike came with Rita electronic ignition and i have it wired up exactly as below:




When i've shorted the wire that on the diagram connects to the existing 12v feed (starter button) straight to a live fuse, nothing happens - until i remove the wire from the feed and i get a spark!

another thing I have noticed is when i turn the key the opposite way - (the lights come on, but wont crank) when i turn the key back off i get a spark too!

Any suggestions? i'm totally at a loss now... all the wires are nice and new, ive got good continuity from the wires coming from the pickup at the front of the engine, and good earths... as soon as i get a spark on cranking my re-wire is all done and i can start getting the bodywork done... would be really ncie if i can get the rebuild done for a ride this summer  ;)

Thanks in advance for any help  :)

Andy

[wrbix]

Don't/can't quite follow your do this -> "spark" diagnostics.
Got a voltmeter so you can actually measure where thing are hot and not?

[Idontwantapickle]

Go simple and then back up through the system and find the error.
So start by disconnecting ignition box entirely and just leave the hot wires on the coils. Use a test light to confirm there is power reaching there. Hook up a plug to the plug wire and set it on the engine case where you can see it. Attach a wire to the other side of the coil and use it to trigger the coil by touching the case and pulling it away, with the power on of course. When you break the connection it should spark.
If this works on both coils check the diodes shown in your diagram between the coils and the box. The positive side of the diode needs to face the coils.
After this is gets more complicated so try this stuff first.
Good luck!

Hunter