I need advice. Last season I lost spark at the rear cylinder. I replaced the coil,bike ran for about 7 minutes,stalled and hasn't started since. With some tips from Gerhard, I have determined that while attempting to start the bike,voltage drops to 9.74 volts at the Digiplex unit. I have a sneaky idea that this maybe part of my problem. I have tested the pick-up & my battery has 12.76 volts in it. Any ideas??? Should I invest the 100.00 in a starter upgrade wiring kit? Your input uis GREATLY appreciated,THANKS

I think the voltage dropping to 9.74 volts at the digiplex during start up is normal (from a standard motorbike battery) as the starter motor is sucking up a lot of current cranking the motor.
I would check and replace leads and plugs, if they haven't been replaced for a while

I think that badhabrace is onto it. I found that with mine that a drop in voltage will cause the digiplex to temporaraly chunder, like when I switched on the headlights the thing would backfire but recover almost immediately even tho the headlight remained on. Try hot wiring the digiplex by running a wire from the batt + to the power input to the digiplex to prove the fault . the culprit is most likely either the main harness plug to the right hand switch block or the kill switch or even the ignition switch itself . Do a volt drop test and you will see .

Clean all the electric connections and replace the bad ones.
I don't think it was a starter issue.
Ciao

Agree with McTool.
I have had voltage drop problems with both the ignition switch and the kill switch.
The wire soldered to the kill switch terminal was fractured to the point where there was just one or two strands of the wire left hanging on when I found it.

If you have a look at my "Wired Paso ( owner )" thread you will see that I have fitted a couple of relays . the top one feeds the digiplex and the coils . The relay is activated by the brown wire coming from the rh handle bar switch ( previously only fed the digiplex ). Both the relays you see are fused relays and are connected to the battery ( red cable going round the back of the fuse box in pix .... also feeds fuse box ) the other ( lower ) relay is the main relay which now feeds into the green / black wire . This relay is activated by a feed from the ignition sw ( small red wire on rh side of fuse box) Just make sure you feed the correct side of the ign sw or your park lights wont work .
Pink wire from fuse box feeds the fan via thermostatic sw , brown wires ( paired together ) are from reg , and red wires feed head light relays which are right up by the headlight . I am going to replace the battery cables too as I have previously been caught out by a faulty earth cable on my SS.... cost me for a battery and a set of starter motor brushes before the penny dropped