Here again is the difference between an early 1100 2 Valve and the later 1200 4 ValveHere is the 2006 just a single Start Relay fed direct from fuse "C" (strictly speaking through 2 fuses in series)[You must be registered and logged in to see this link.]
I suspect this didn't give too much trouble but the wire from relay to solenoid is far too small so change it out for sure.
And the 2008 downstream of the ignition switch from fuse 2[You must be registered and logged in to see this link.]This bike has 2 Start Relays but now the start relay is fed down stream of the ignition switch through a lot more wiring
Martin's video right near the start indicates what happens by the light going dim, his headlight is fed from the weak yellow wire that feeds the Start relay.
I believe the second Start Relay was added to later CARC bikes to counter the first relay dropping out on under Voltage, this is just at the very start while the
solenoid is pulling in to close the main solenoid contact. If it manages to close the cranking will be normal.
Again the wire from relay to solenoid is too small, change it out.
I am fairly sure if you have modified the 4 Valve with a direct fuse you can unplug the second relay, I don't have a 4 valve to play with so I can't try it.