starting capacitor?

Couple more questions. What does the starting capacitor do? This is another one of those cannisters with a spring attached..lol. Is this something that can be removed from the wiring system and still allow the bike to function? Note: I am running a boyer bransden ignition. Thanks

Think of it like a tiny battery with no storage capacity. If it gets old enough it will drain your regular battery. If it works well it will try to make up for the low spots in your rectified voltage. When it works it helps, when it does not work it is sometimes unnoticed and sometimes a battery drain.

The 2MC capacitor also enables the bike to be started with a flat battery (or no battery) with the original points ignition, but with electronic ignition you may not be so lucky?

It can be removed if it is found to be draining the battery, as the 2MC only has a limited lifespan.

The capacitor want help at all without points system. It will give a spark to crank your bike without even having a battery installed if you run the old points. Boyer systems need a constant 12 volts to produce a spark.

Thanks again!

Another question answered. Thanks very much!

I did use an old simpson volt meter when I checked my capacitor voltage and it always showed 0 after the instant the meter touched the capacitor post. Never tried it with digital type meter. My bike would not start without a small battery hooked up.

When testing the capistor does it need to be disconnected or can it still be wired up and the two leads tested with a meter?

It can be left connected to ground, but it should be disconnected from the battery, otherwise you will be measuring battery voltage.


I test my 2MC by removing the fuse, and leaving the bike for a few hours, or even overnight.

I then switch the ignition on (with the fuse still removed, and lights etc. switched off) and if I see the charge light and neutral light (it's a MkIII) flash on briefly, then I know that the 2MC has held its charge.

The problem with the 2MC is that it becomes conductive, eventually, so it can cause the battery to drain. If an owner finds their battery goes flat quickly when the bike is not being used, and a 2MC is fitted, then (provided it's not being caused by a faulty battery?) try disconnecting the 2MC.