Anyone know what this is?

Sandgroper

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Hey everyone I was looking for some help identifying this part. I’ve tested the output on it and the terminals in the yellow marked circle read 11.1 volts and the terminal in the red circle reads 3.4 volts with the engine running. I’m thinking it’s a voltage regulator/rectifier but why would my XS have one under the battery already? Thanks for your help.
 

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Jim

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Yes, that's an old mechanical regulator (just the reg.... not a rectifier).
Yamaha mounted it to the battery box for vibration isolation.... the batt box is rubber mounted.
 

Sandgroper

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hey guys just a progress report on that voltage regulator of mine. It was faulty and producing too much voltage. I took it apart, tested it the way my workshop manual specified. I ended up sandblasting to contact points and terminals then thoroughly blew it out with compressed air followed by electrical contact cleaner (that was important to get proper ohm readings) I then adjusted the little phillips head screw to get desired voltage at 2500 RPM. Now I am happy to say I have No more blown headlight globes while riding at night time, no more soiled underpants, huge improvement in performance and fuel economy. I have been trying for ages to sort out my bike thinking there was something wrong with my carbies. I kept a diary of everything I did to the carbies with no great improvement. Once I sorted out that darn voltage regulator its a new bike. My knowledge of electrics is limited but I would really like to know the connection to such a good improvement. Im running an aftermarket electronic ignition and did away with the points, could the excessive voltage have had an impact on the ignition? Thanks everyone!
 

jpdevol

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It would depend on how that ignition was wired into the bike; if through existing factory harness there should be no impact as battery acts as a regulator of sorts.
 

jpdevol

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yep, you're probably getting a better spark at idle. Just adjust it as normal to ~1100rpm
 

Jan_P

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It would depend on how that ignition was wired into the bike; if through existing factory harness there should be no impact as battery acts as a regulator of sorts.

Maybe not entirely correct
I have been working with excavators and there was a " Shock " valve should sudden pressure increase occur then that valve would open as a safety valve
There was also pressure regulating valves keeping pressure down ..Which if not working could have effectual Consequences.
The enthusiast from the Airplane sectors know this.

Now on an XS 650 the Voltage Regulator has its purpose to limit the Voltage at some chosen point in that wiring system
to ca 14 V When Measured across the battery that is between + and - where minus is ground earth.

But depending on the circuit that same Voltage ( if I get it right ) also goes in to the System as a whole
So the overall Voltage in the system akin to that in hydraulics is what the regulator set it to.

So the factory machine did come with points and a " Stoneage " ignition advance unit and a Mechanical regulator.
It was not so important to have an exact regulator ..The alternator could take a beating but they are generally the top dog in the system
and can take some hits, Generally speaking

So what happens when electronics ,,TCI or other comes on the bike. Yamaha had what I believe is called " Analogue " Electronics.
And Modern day have small Computers inside them " Micro controllers " in them . Digital 0 or 1 and are driven via extremely small current and voltages

The Point ( no pun intended ) is that the modern day electronics might not be able to withstand bouncing Alternator brushes and varying
System Voltage

Say for Example that the aftermarket ignition is designed for 11,5 to 14,4 V
Faulty regulator " Stoneage " type feeding the system 14.8 V the controller is not designed for that
It assumes modern day regulator .
So depending on what is inside code wise and hardware wise.
it can fry of course the higher Voltage with the same Resistance --> More power more heat.

And it is not certain that the program code has a loop

If Voltage is over 14,4 ..> Then do this..
And instead feeds the rest of the code with garbage..

I once had a Boyer Bransden ignition that dropped one cylinder warm days ..with an overcharging stock regulator
Bike ran fine cold but warm not so .I believe it was the over voltage.
 

jpdevol

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If wired through stock harness, the ignition gets its power from battery through IGN. switch to fuse block on 10A fuse, so.....
 

Jan_P

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I
If wired through stock harness, the ignition gets its power from battery through IGN. switch to fuse block on 10A fuse, so.....


Not sure we are talking about the same thing here please look at the snip below I believe it was a 79 year model

If the machine is charging say 14 V the red coming from the rectifier is higher than the battery Voltage and a portion of the charging current goes to the battery 14--12 V
the other part goes to the ignition lock .
If the rotor shorts out so the Voltage after the regulator is low then battery is higher feeding the ignition lock and you can drive until the battery is empty
I have been wrong before but cant see it at the moment



1659803855146.png
 

jpdevol

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I reckon it's possible to get a voltage spike through all this to the ignition circuit...but, likely??
fusebox detail.jpg
 

Sandgroper

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I really appreciate everyone’s input. Learning from others has helped me a lot and got me out there enjoying my bike. Being a novice at electrics has had its challenges believe me. I have made sure to take plenty of pictures and kept a running diary so that the one thing that makes an improvement gets recorded. Trying not to change too much at once helps to isolate problems. I’m convinced now that my electronic ignition really didn’t like the extra voltage being sent to it. My throttle response is so much better and smoother from closed to fully open. Cheers everyone and thanks again. Safe riding.
 
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