What is a coil and rectifier? (motorcycles)

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InternetSwag

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Title^, and does each bike have a different type? Looking at a 1991 400 FZR. Not going to buy a new bike, just always nice to look at the ones on websites and maybe learn a bit.
 
The rectifier is what charges your bikes battery while your engine is running. Busted rectifier means your battery ends up running dead eventually because there is no charge on it...

Coils depends on which ones you are referring to, but I am assuming its the ones connecting to your spark plugs via the sparkplug cap to allow them to fire. If your coil(s) is/are dead, your plugs wont fire inside the combustion chamber.

The other coils are located on your magneto... which is responsible for generating a high voltage to power your plugs.
 
Last edited:
Pornolio said:
The rectifier is what charges your bikes battery while your engine is running. Busted rectifier means your battery ends up running dead eventually because there is no charge on it...

Coils depends on which ones you are referring to, but I am assuming its the ones connecting to your spark plugs via the sparkplug cap to allow them to fire. If your coil(s) is/are dead, your plugs wont fire inside the combustion chamber.

The other coils are located on your magneto... which is responsible for generating a high voltage to power your plugs.
Click to expand...

Ohhh I understand! Makes sense I always wondered why my bikes battery never runs out.

Fascinating. Is it expensive to fix?
 
Rectifier wise, the quickest fix would be to replaced the unit. The older Honda VFR's / CBR's, esspecially 400's are renowned for busted rectifiers. The coils on your magneto can be fixed, but very few auto-electrical places will do it for you on motorcycles.

If its just the battery that keeps running down, start with the rectifier, they are 99% of the time the culprits... esspecially on grey imports that stood many years in auction houses / containers waiting to be shipped to their country of destination. Secondhand rectifier should cost around R350 / R500 more or less from a reputable dealer secondhand.
 
A magneto is a generator. Think EMF. As your engine is running you are generating electricity. This electricity is put out as AC voltage. Your bike or car uses DC voltage. So to get DC from AC you need to rectify the voltage. This is what a rectifier does. A spark is a few thousand volts. Your battery is 12V. So to get this high voltage you need a simple electrical circuit. This is the coils job. Stepping up the voltage from 12v to a few thousand volts.
 
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