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Complete failure? No lights or voltage to anything ?

If that's the case, start by using a VOM to check battery voltage across the terminals; loosen/clean then retighten the battery connections; replace the fuse (on general principles); and test again to see if you have power into/out ofthe switch before proceeding down the line.
Sorry, I should have explained further, there is a healthy reading from the battery, rectifyer, coils & the live feed to the capacitor. However, there is a poor reading from the capacitor itself & zero reading from the negative wire to the capacitor.
When you press the horn on my bike, it works wether or not the ignition is on or off. Now the horn doesn't work or the lights, brake lights etc. There is zero reading at the horn. The bike doesn't even cough when you kick it over (its always a first time starter). The red (live wire to the capacitor had broken off at the little connecting spade. I re-soldered it but to no avail.
Thanks for your replies.
chiefdeal said:
The red (live wire to the capacitor had broken off at the little connecting spade. I re-soldered it but to no avail.

The broken red wire would have isolated the 2MC capacitor from the electrical system, therefore if the problem occurred before you re-soldered the wire, then the capacitor is unlikely to have been the cause of the problem?

The easiest way to check if a 2MC is causing a problem is to disconnect it. Just make sure the brown/blue wires that connect to it are connected together in some other way.
Yes, I have had two that failed - the first blew the the fuse, the second kept draining the battery. I'm at work at the moment but if I remember rightly the terminal with the double connection will read battery voltage as it's connected directly to it, but that does not mean anything. Like previous posts remove it, but insulate the live wires and run without it. The belief that it would start a commando were somewhatt misleading - you might be lucky first try! it's mounted the wrong way up - design fault, just dismantle one and you'll see why, as it's got a hole in the terminal end under the crimped on plastic plate, the capaciitor winding is in the bottom of the ally can not near the terminals. I have done 6,000 miles with it removed and had no problems, modern batteries should be more than capable to deal with the rough DC waveform from the rectifier and zeners.
A battery is a very large capacitor, much more than the 2MC. It (the Cap) is not really necessary unless you want to run without the battery.

69 S project
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