Regulator/rectifier numbers

Newbie from down under,just replaced the reg/rec on my r because the stator wires were fried .
Previous repair was bullet connectors/ so i replaced with a multi pin plug and soldered ends.
I have a few from other bikes ,Question what do the numbers mean on the top ,first numbers i assume are part numbers SH541-12. 5.0, SH541-12 3.4 ,SH541-12 7.1 what do the second numbers mean.How hot should the reg get i cant keep my hand on it it gets so hot after a short while.If its stuffed whats a good replacement for it.
Any advice greatly appreaciated.

Hi Tom,
I had to change out the stator and reg/rec on my 87 FF. The stator is a Chinese pattern part and the reg/rec is from David Silvers UK, and up-rated compared to OEM.

As far as I’m aware, the reg/rec should not get any hotter than it would take to melt the insulation on the wiring - so if you can’t bear to hold you hand on it, then it is getting to the 50c plus range and close that area.

There are tests for the stator to see if ti is still working as expected, start there, but a new reg/rec is not that expensive and would be a good step from the OEM ones, which even if OK, is still going to be a 30 odd year old piece.


Thanks ascalon for a quick response ,will read up the manual for testing stator .
Will order a new reg anyway ,

Actually, one other thing.
I’ve heard of a lot of people going the belt an braces route by plugging in a 12V PC cooling fan and attaching directly to the reg/rec. There are 5" ones that are fairly slim line that could move enough air to be effective.
They would be easy to splice in to the feed for the fuel pump, as that is switched with the ignition.
That said, I’ve not had any issues with mine since the above set up was done, and I use a Lithium battery with no issues (XRacer).

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On my 94 vfr750 I was getting around 80c with new Japanese regards rect. Put on a Pentium 4 cooling fan and temp dropped by 40c. Cost me zero dollars and maybe 15 minutes. That was probably 4 years ago and it still works perfectly.
Dodgy deeds done dirt cheap.