I'm still not sure what's going on with my magneto coils. This is the third or fourth one I've lost in a years time on 2 different motors. I'm losing count.
Each one has failed the same. The coil winding goes open. None of them had a bad solder joint. This tells me they all burned out.
The first 2 died within a few hundred miles of each other last summer when it was real hot outside. I was pretty sure a combination of high ambient air temperature, plus the stock kill switch shorting the coil wires together was probably the cause. This was just a guess though, and none of them actually failed when I hit the kill switch, now that I think about.
The symptoms are always the same. I'm always riding along at high rpm when the failure occures. The motor will studder a little, then will quickly get weaker and die. Testing reveals the coil winding to be open. A new magneto coil makes everything good again.
I attempted to stop this from happening by changing the kill switch from a momentary switch, to a single pole switch wired where it just opens the circuit to kill the ignition. This kind of switch doesn't short the coil wires together.
This latest failure happened on my newest bike at less than 200 miles. It's had the new style kill switch from day one, so it was never subjected to having it's coil wires shorted together even once. Plus it went into service in December so it's never seen high ambient temperatures either.
Sunday I rode it home from a long ride at over 7000 rpm for close to 20 miles. When it failed yesterday it was the next time I went riding after Sunday. It failed after about 5 miles, and shortly after getting up to high speed.
Lacking any better ideas, I guess the next thing I'll try is reducing my spark plug gap. I've been running 0.030". I'll try 0.024" for a while and see what happens.
I'm open to other suggestions.
Each one has failed the same. The coil winding goes open. None of them had a bad solder joint. This tells me they all burned out.
The first 2 died within a few hundred miles of each other last summer when it was real hot outside. I was pretty sure a combination of high ambient air temperature, plus the stock kill switch shorting the coil wires together was probably the cause. This was just a guess though, and none of them actually failed when I hit the kill switch, now that I think about.
The symptoms are always the same. I'm always riding along at high rpm when the failure occures. The motor will studder a little, then will quickly get weaker and die. Testing reveals the coil winding to be open. A new magneto coil makes everything good again.
I attempted to stop this from happening by changing the kill switch from a momentary switch, to a single pole switch wired where it just opens the circuit to kill the ignition. This kind of switch doesn't short the coil wires together.
This latest failure happened on my newest bike at less than 200 miles. It's had the new style kill switch from day one, so it was never subjected to having it's coil wires shorted together even once. Plus it went into service in December so it's never seen high ambient temperatures either.
Sunday I rode it home from a long ride at over 7000 rpm for close to 20 miles. When it failed yesterday it was the next time I went riding after Sunday. It failed after about 5 miles, and shortly after getting up to high speed.
Lacking any better ideas, I guess the next thing I'll try is reducing my spark plug gap. I've been running 0.030". I'll try 0.024" for a while and see what happens.
I'm open to other suggestions.