please help wiring guru neede

please help
hi, got a 1st gen vfr750 fg rc24 1986. got wiring problem ???????. with ign on & kill switch off, motor will turn over & fuel pump is working, but no spark. with the kill switch on it pops the ign fuse. i have a basic knowlage of wiring, but i'm prity good in all other areas. common sense tells me its a bad earth, checked all connectors for power/continutey. all seeems ok.this is really puzzeling me & i've come to a stand still.please help me obi one canobee !!!!!! your my only hope. cheers.DAZ. great forum by the way. :smile:

 

I am not a guru especially if bike is not a VF500F.
I suppose your bike shares the same architecture of ignition as the VF500F so here it is:

My first suspect would be shorted igniter unit. Remove each to verify the defective.
There is a chance of repairing if just the output transistor is shorted.

I hope it helps.

 

thank you Blitzas, will check these tomorrow, just trying to eliminate the obvious first, i'm hoping it is just a short somewhere & not the igniter unit.the bike was in a right state when i got it, been stood for 14 years in a garden shed. i'm building a CAFE RACER out of the old girl, just fancied building something different, will post pictures when its finished, not long now, just this wiring glitch & fresh paint.

 

There is most definitely a short somewhere but without inspection it is impossible to tell whether it is just a frayed wire or internal to a component such as the igniter unit.

 

I would start by disconnecting the CDI boxes (Igniter units) the coils, and the connector that goes to the pulse generators. Plug them back in, one at a time, with the Ign switch, and the kill switch on. Watch for the fuse to blow. The last thing you plugged in is bad. I'd have to hit up a diagram to know if there's anything more that runs off the kill switch, but I doubt it.