What Is This Please.

Its a zener diode, used for dumping extra current from the charging system...they normally have a heat sink attached.

 

Its attached/earthed to a hefty piece of metal so probably adequate if its been functioning for some time.

 

A heat sink is recommended as it dumps excess current to stop boiling the battery, there used to be an finned cast aluminium one fitted to alternator twins.

 

I have used zeners bolted to the frame or a battery box...as long as its got enough mass to dissipate the heat its fine...but if you want the stock look you need one of these.

 

The wind cools the heat sink for better efficiency, less chance of electrical breakdown

 

I know how they work ...was just saying that if the item they are bolted to has enough mass/area then heat dissipation is no problem and often better than the std item and they will work perfectly efficiently never had one fail from needing better cooling....personally i prefer a solid state all in one reg/rec.

 

Being an ex electronics engineer, the zener diode SHOULD have the ALUMINIUM heat sink attached to the body of the diode, the surfaces that touch should be very clean and dry with a smearing of heat sink compound, this transfers the excess heat more efficiently to the aluminium which has got a greater thermal coefficient for dissipation AND has a massive surface area for heat loss AT the exact point required ie at the diode junction internally. Also if the bike is a keeper the originality looks better if required
Regards Jeff

 

Being an ex electronics engineer, the zener diode SHOULD have the ALUMINIUM heat sink attached to the body of the diode, the surfaces that touch should be very clean and dry with a smearing of heat sink compound, this transfers the excess heat more efficiently to the aluminium which has got a greater thermal coefficient for dissipation AND has a massive surface area for heat loss AT the exact point required ie at the diode junction internally. As long as the rest of the charging circuit is working within its normal parameters it should be fit and forget hopefully. Could check voltage across when constant revs, say 1500.(DO NOT short out)
Also if the bike is a keeper the originality looks better if required
Regards Jeff