Multimeter Coil Test – Twin lead coils Primary : multimeter on 200 (ohm side) probes on + and - terminals of coil primary should read around 2.8 ohms Secondary : multimeter on 20K (ohm side) The secondary windings are isolated from the primaries. These are double-ended coils, so measure the resistance through both spark wires (without the caps). secondary should be around 15K ohms
@GreyImport hi again - it’s been a while, thanks for the information on testing coils. Do you know a lot about cdi units? I have a 1995 XJR400R which will rev free not under load but break up badly around 8k rpm under load. Figuring out if it’s poor cdi? Thanks
More importantly, most likely failures are ends of copper wire into caps screw and the 10kOhm resistor within the cap - the majority of mine on 3 bikes were corroded to worthlessness (retaining screw doubles as the plug connector, revealing lump of oxide). Coils and CDI are out of weather, away from the heat. So go cap-cap for 33kOhm.
The coils and leads I have don’t have resistors in the caps at all - they’re just straight connectors.
For an FZR250, leads without resistor caps are incorrect. Someone has bodged it. They will either need 5k ohm or 10k ohm resistor caps.
Thanks for the quick response. So I have 5k ohm resistor caps which all read within 10%. I’ll put those on and see what happens. Is the resistor to allow build up of charge or something?