2MC Capacitor Life

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jsnorton

jsnorton

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Does the Capacitor breakdown with age ? I am still using the original 45 year old 2MC and would like to know if there is a way to test them with an Ohm meter, and what good readings should be ? I heard you can test them by applying 12 volts for a minute then disconnect it and check the voltage in 5 minutes.
73 850 still using points. I don't want to replace it if it's still good. I run a battery and the bike starts good, but would like to know if it will still keep running if my battery should die on me.
Thanks for your help.
 
Yes, expect no more than 4 to 5 years if made the same as original (but mine lasted 25 years ;) ), longer out of modern manufacture alternatives. Test is applying 12V and then seeing how long it decays, not got the data but 5 mins sounds good as in real life it only needs to hold a charge for a few seconds. I have replaced mine and yes if the fuse goes while the bike is running the bike runs fine. As I have a Boyer it needs a good bump start to get it going, kicking just gets a few farts.
 
I fool around with old vacuum tube amps that use similar 50+ YO electrolytic capacitors and have learned that if they were regularly used they are far more likely to be good then if they sat for years...
 
My '74 bike has original 2MC...bike has 8300 original miles when I got it a year ago....capacitor tested fine. 12v applied for 1 min, then held charge for over 15 min.
Apparently it is important to hold them vertically to prevent the dielectric fluid within from leaking away from the internal plates.
 
Charge the capacitor with a 12V battery and a small bulb in series .
When the bulb goes out , the cap is fully charged .
It will take only a second or two .
A good cap will hold its charge for weeks .
Check with a digital volt meter .
I would not use a cap that shows less than 10V after one hour ..
 
Do bear in mind that if, you have points ignition, it will fire and start a bike with only 6volts in a battery, BUT electronic ignition, NO CHANCE!
 
Bernhard said:
Do bear in mind that if, you have points ignition, it will fire and start a bike with only 6volts in a battery, BUT electronic ignition, NO CHANCE!
Click to expand...
Pazon Surefire ( for one ..) will start quite easily with a good capacitor and battery disconected .
 
Bernhard said:
Do bear in mind that if, you have points ignition, it will fire and start a bike with only 6volts in a battery, BUT electronic ignition, NO CHANCE!
Click to expand...
Yep with only 6 volts vou won't get electronic ignition to run
But I have run a commando on just a 2mc capacitor no battery and Boyer ignition
 
Of the capacitor fails open it stops working but the bike will run normally, if it fails closed it passes electricity to earth and the battery loses charge.
 
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