I have relays on my CB750.
I got the idea on this forum where the weak ign switch was discussed. I do not trust the handle bar switches with very bad connection either. Thin wires soldered direct to small flat contact points. 5A thru those? no thanks!
Handle bar switches have no higher wattage anymore when they control relays for Lo Beam, Hi Beam, Horn and Ignition. Plus a 5:th reversed relay switching off (open) front parking light when Lo beam is ON. The cheap general relays made for cars have become smaller. Easy to connect. I disconnected the Headlight wires inside Headlamp, let the wires switch on relays instead. New + wires routed from battery under tank to the relays. Ignition relay beside fuse box, feed coils and ignition module (Dyna or Hondaman that I use now) When ign switch power on the coils, it power on the relay only. From relay to coils (black/white where I opened the circuit, one wire back to relay mounted beside fuse box, 12V AWG 15,4 wire back to black/white feeding coils). Thinner wire to ign module 12V 0.75mm2 (AWG 18,2)
Most of the bad Honda connectors are repalced with thicker insulated sockets/pins for the thicker wires.
The relays control 12V power direct from the battery, hanging fuse close to battery. Thicker wires AWG 15,4 (1,5mm2).
My dual snail horn did not work without relay and thicker wiring.
I'll update the ground wires (green cabling inside the Headlight) with thicker wiring direct from battery (-).
I have added ground wires from ign coils bracket to frame.
***I found a weak point in the HONDA electrical design, K6. ***Brake switches, front and rear get power from black wires (15A main power for the entire bike) If the wirings get a short to ground the bike will stop direct and headlight OFF!!! Safety Hazard! How do I know that? I'm happy that I got my 2 stops close to home or friend. Bad plug insulation at rear switch at fot pedal, caused short cicuit.
I have not reconnected it yet, but
it would be better if brown (5A) wire will feed these switches. I can use the free end brown cable at front plus route a cable from under the seat to rear brake switch.
The std fuses are still there (found Autofuses 7A, 10A , 15A (no 5A) on eBay.de, diffcult to find 25x6,3mm fuses here) plus some other modern mini fuses for the new thicker cabling the relays control. Fuses ready to switch back to std if a relay fail. The smallest fuse will work otherwise.
The reversed relay controlling Parking light have an own small fuse hanging in the wire feeding the parking light. I had a T10 bulb with internal short to ground that made HI/LO not functional. Thats why switch of when LO to not interfere if that strange problem will happen again. Areally powerful CREE LED T10 bulb will not destroy LO beam light pattern either.
This sound complicated but is very easy. Everything added to the OEM, easy to remove if OEM style is needed. All connectors crimped on the wires will match.
The new LED H4 bulb forced the relays out of the headlamp.
I have to secure them better and less visible. Relays seated in holders where the wires are connected. This take more space but safer and easy to replace a relay.
http://images.biltema.com/PAXToImageService.svc/product/large/2000017799No flat connectors and single wires to each relay.
Finally: The strange thing here is that I used my bike during almost 80.000km's back in the days without realys. Last 30.000km's no ignition switch at all. Replaced by a hidden std switch (on-off) under the tank using the old harness from ign switch.
Not so much burning electrical system either. Except a few times when a wire could be squeezed somewhere. Just to feel which wire that was hot. Usually under the handle bar switches against handle bar where wires were routed outside.
