rectifier max output voltage?

[Robert Dell Aquila]

Yes, pretty much every one of these bikes needs their wiring gone through and cleaned up. That includes wiring AND all the connections. If doing all that doesn't solve your voltage drop issue and you still want to do the regulator relay mod, here's how to wire it up .....

Pulling the power from as close to the battery as possible is best so that you avoid as many connections (and possible voltage drops) as you can. Do take a voltage reading at the positive battery terminal and then again at the solenoid connection. You only have a short (maybe 6") battery cable there but it could be bad, or maybe it's connection points are.

As far as relays go, there are several types. Here's a link that will educate you about them .....

https://www.12voltplanet.co.uk/relay-guide.html

Any of the common types you'll need are readily available at most auto parts stores for a couple bucks.

Thats awesome thank you. A couple of questions though. Does the relay just float, I know you connectba wite to ground but what do you do with the relay body? Also, when you say starter relay bolt you mean the starter solenoid bolt? Thanks a bunch

 

[XSLeo]

Most people call it a solenoid buy Yamaha calls it a starter relay.
The bolt you want to hook to is the one on the battery side.
You can mount the relay most anywhere, even a zip tie to the frame will work.
Some one earlier asked if the regulator and rectifier were the same thing, kinda sorta, on the 70-79 bikes they were separate units, The regulator was mechanical.
On the 80 up bikes the regulator was swapped to a solid state unit and was combined with the rectifier into one unit.
On my 75 I had one of the Chrysler regulators and the needle would bounce around at higher revs. I thought it maybe from vibration. I thought it may have been jumping up to too high a voltage.
Testing with a digital meter was tough to do. No easy way to keep the leads hooked up going down the road. So inconclusive on that attempt. I got one of the Fiat regulators and installed it to see if it made a difference. The volt gauge on the bike still bounces around.
I will have to build a set of test leads with ring terminals to hook up a multi-tester. A bit of tape to hold it on the bars and drive it that way.
If it does point to erratic charging, that maybe why the Lithium Ion batteries failed. From what I understand they don't like high voltages.
Perhaps a weak ground somewhere or other bad connections.
Leo

 

[FLEA]

normally if reg /rec goes bad you get a large voltage reading when reving , is it possible to get a zero increase when reving the engine .. ie showing 12v at idle .. rev motor and no increase .. checked pma and all seems good , fuse is good , connections all good , never heard of a reg/rec shitting it self in this way but doesn't hurt to ask

 

[5twins]

Follow your battery cable from the battery positive terminal to the solenoid and connect the relay red wire (running to the #30 relay terminal) there. Mount the relay to the battery box or frame somewhere, where ever is convenient. If you have pods, the sides of the battery box should have a spot. If you still have the airboxes on there then you will probably need to find another location. Keep in mind that the battery box is not a suitable grounding point because it hangs off of rubber mounts. The relay ground wire will need to be run to the main frame somewhere.

 

[Robert Dell Aquila]

Follow your battery cable from the battery positive terminal to the solenoid and connect the relay red wire (running to the #30 relay terminal) there. Mount the relay to the battery box or frame somewhere, where ever is convenient. If you have pods, the sides of the battery box should have a spot. If you still have the airboxes on there then you will probably need to find another location. Keep in mind that the battery box is not a suitable grounding point because it hangs off of rubber mounts. The relay ground wire will need to be run to the main frame somewhere.

I did the mod on my bike, thank you. Relay was about $6 at autozone. Just one question. I went to go kick my bike after installing the relay to check the voltage and it wouldnt start. Would installing the relay have anything to do do with this? I'm assuming no because its not going through the coils or anything.

 

[5twins]

No, it shouldn't cause it to not start. The relay and voltage regulator are part of the charging system, not the ignition circuit.

 

[Ozboy]

Hey 5t looking at the wiring diagram before the 8 pin plug the brown wire goes to the brushes right?
So the brushes will be getting this volt drop too which wouldn't be good. So i guess a SPDT relay supplying the reg/rec and another for the brushes would make sense if you go down the path with a relay

 

[5twins]

The diagram you posted is for the '80 and later type charging system. Yes, on that system the brown wire does feed both a brush and the regulator. On the '79 and older system, it doesn't. It only feeds the regulator. But on the later system, I suppose you could use two relays if you wanted, a 2nd on the brush power feed wire. But the need for any of these relays would depend on whether you're reading a voltage drop on the brown wire compared to the battery. If you can't fix that by cleaning all the wiring and connections, then a relay would be a good idea.

 

[mrtwowheel]

Some voltage loss through the ignition switch and other switches is just gonna happen. Clean these switches and you will see that the contacts made in the switches are about the size of a pin point.

Scott