Simon Spiers
XS400 Member
We all know how touchy the xs250 and 400 are at starting, one of the main problems is the fairly weak spark.
On testing my ignition system I find that with a fully charged battery, I loose some 3 Volts at the primary of the ignition coils. This is mainly due to ageing wiring that was underrated when new and oxidised contacts in both the ignition and kill switches along with the various connectors.
So I have come up with a simple solution. I use a single pole relay mounted above the flasher relay to take power straight from the battery via a 10 Amp fuse and supply the battery side of the coils with a short run of cable reducing the voltage drop to less than 200mV. The double bullet connector under the tank supplies the coil of the relay, the other connection of the relay coil (not ignition coil)is connected to a good ground (condenser screw). The the normally open connections of the relay feed the two wires of the ignition coils, and the other contact is connected to the battery via a fuse. You must use a fuse in this line as the bikes fuses will not protect the ignition coils any more.
An improvement in starting especially with the electric starter should result as the coils always get full volts from the battery.
I hope this is of some help
On testing my ignition system I find that with a fully charged battery, I loose some 3 Volts at the primary of the ignition coils. This is mainly due to ageing wiring that was underrated when new and oxidised contacts in both the ignition and kill switches along with the various connectors.
So I have come up with a simple solution. I use a single pole relay mounted above the flasher relay to take power straight from the battery via a 10 Amp fuse and supply the battery side of the coils with a short run of cable reducing the voltage drop to less than 200mV. The double bullet connector under the tank supplies the coil of the relay, the other connection of the relay coil (not ignition coil)is connected to a good ground (condenser screw). The the normally open connections of the relay feed the two wires of the ignition coils, and the other contact is connected to the battery via a fuse. You must use a fuse in this line as the bikes fuses will not protect the ignition coils any more.
An improvement in starting especially with the electric starter should result as the coils always get full volts from the battery.
I hope this is of some help
