Electrical Theory…

Electricals on bikes, everyone hates them right? Why? There is a perception that it’s difficult to understand and is some sort of black magic. It would be easy for me to sit back here and say it’s all basic stuff with the AG200. The problem is I have been immersed in electronics and technology all my working life – nearly thirty years!  So what I find relatively straightforward others may have trouble getting their head around. I get it.

Problem is geeks and nerds (I class myself a geek, don’t know if I qualify as a nerd!) usually have a bad reputation for trying to explain concepts that they understand so I’m going to palm this one off! Down below are some links to some old Yamaha Training info that I had lying around. This is some entry level stuff that hopefully will give you a basic understanding of how electrics work on most bikes.

Electrical Charging Systems

Ignition systems

CDI systems

Electrical Systems 1

Electrical Systems 2

Electrical Systems 3

After reading all this you should have a better understanding of the electrics of your trusty steed.



4 thoughts on “Electrical Theory…

  1. Dear AGMan,

    Have some issue with my ignition coil assembly I think (the black part that the spark plug lead connects to). I’ve noticed some smoke when trying to start at times – and noticed that it’s the wire that comes off the main harness to the ignition coil. The black wire has been getting hot enough that it’s melted in two places! Does this mean a faulty ignition coil assembly? It usually works fine otherwise.

    1. Hi Tej

      It may not be the coil. I’d remove the coil from the frame and have a good look at it. If there are any signs that the plastic housing is melting then it may be shot. I’d be having a real good look at the connections to that wire that went to to the coil. If there is any corrosion it will introduce resistance that will cause heat, so clean any plugs and sockets up as good as you can and see if this fixes the issue.


      1. So I swapped the coil from my other AG. That was working fine. Both had pretty rusted terminals – and I’d imagine rust adds a lot of resistance, so I scraped out most of it and ensured that I screwed the wires in real tight.

        I also swapped the starter relay.

        Still having the exact same problem though. Push the starter and a lot of the time the initial symptom is as if the battery is really weak (even with a fully charged new battery that’s screwed in firmly) – but then it takes and swings and the black wire to the coil heats up enough that it starts smoking.

        I’ve also been having lots of trouble starting up the bike when cold – kickstarter works at times though. Starts first time when engine is warm though.

        Any ideas on where to look further?

        1. Aah think I solved the starter issue – unscrewed the bolt that the earth cable to the battery connects to. It was pretty badly corroded – cleaned it up and seemed to be working ok! Just sold the bike so only tried swinging it 6 or 7 times – but each time it did without hesitation.

          I also noticed [on it (and the last one I have)] a popping sound – discovered that this was some sort of blowback coming out through the intake manifold from the engine. I actually saw the manifold move back (the rubber on both manifolds do look like they’re also on the way out). What would cause this blowback? I’d still be able to ride the bike fine, and didn’t seem to be any issues while riding

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