2016 Vertigo 300 capacitor

[JBROWN]

Hi can anyone advise how to test this capacitor from a 2016 Vertigo (it’s got the batteryless upgrade). I can use a multimeter and read micro farads etc, I just don’t know the valves I should see (there are 3 pins, nothing written on the unit). Also would this being faulty cause failure to start (definitely no spark) ?

[lemur]

Generally the capacitor is not a tremendously expensive or special part and worth stocking a spare to test or replace, the primary reason it is on there is because your bike is fuel injected and Fi needs DC power in the form of a battery and or capacitor to supply sufficient electrical power to the DC fuel pump.  Symptom of a failed cap on your ride would be lack of fuel pressure not lack of spark.

[konrad]

A capacitor is a 2-terminal device.  The third terminal is likely connected to one of the others to simplify the bike's wiring.

For reference, the OSSA's capacitor is approximately 22000 uF.  Most multimeters will not read a capacitor value that large.   10000 uF is a typical limit.

If you connect the capacitor to your multimeter on the ohms setting, the resistance will appear small initially, and gradually increase as the capacitor charges.  You can then short the capacitor leads together (discharging it) and repeat the observation. 

The multimeter will charge the capacitor to something on the order of 350 millivolts.  Once the capacitor is charged, switch the multimeter to read volts (or better yet, millivolts).  The capacitor should hold that charge for a long time (perhaps hours) but you will be able it see it slowly discharge due to the drain imposed by the multimeter.

Passing these tests does not guarantee a good capacitor, but it's better than nothing and about all the DIY mechanic can do.

P.S. An electrolytic capacitor is a polarized device. Operating one at its rated voltage backwards will destroy it.  But when testing will a multimeter, polarity is not a concern.  This is because the voltage is so low, no damage will occur.

Edited 46 minutes ago by konrad

[JBROWN]

Thank you for your reply. There is 499 K ohms resistance (increasing) and 504mv dc through the red and back wires (which would have originally been connected to the 9v battery)

Edited 16 minutes ago by JBROWN