Swapping from PMA to stock charging (part 2)

[650Skull]

Post #28 in your other thread

https://www.xs650.com/threads/wiring-in-a-70-79-combined-reg-rect-to-all-points-model-xs650s.52339/

 

[Jim]

IE when gggGary says, “locate the green wire at the regulator plug and make a jump from it to ground…” can I be sure that I would use the green wire on my aftermarket reg?

No. On the '70-'79 bikes, there's a type B regulator. The type B sends power to the rotor on the green wire. shorting that to ground risks frying the regulator.

I see what you're getting at, you want to bypass the regulator and see if the charge voltage comes up, right?
To do that on the B reg's, you need to make a jumper wire that powers the rotor directly from the battery (Bypasses the regulator).
Connect one end to the green terminal at the brush.
Start the bike and rev it to about 2500-3000 revs.
While holding it there touch the other end of your jumper to the battery positive terminal.
That bypasses the regulator and shoots full power into the rotor. If everything besides the reg is good, you'll see a jump in voltage... a big jump.... like 15 to 18 volts.
Don't hold it there long... just long enough to read the voltage. Leaving it there too long and you might start frying stuff.

If voltage jumps way up, it indicates the regulator is bad (not sending enough juice to the rotor).
If there's no change, the problem is likely somewhere besides the reg.

All that make sense?

 

[Jim]

Do these wire colors correspond correctly to the stock reg/rec?

Yes, the early bikes... the type B system. Your bike in other words.

 

[D3viousd4n]

I see what you're getting at, you want to bypass the regulator and see if the charge voltage comes up, right?
To do that on the B reg's, you need to make a jumper wire that powers the rotor directly from the battery (Bypasses the regulator).
Connect one end to the green terminal at the brush.
Start the bike and rev it to about 2500-3000 revs.
While holding it there touch the other end of your jumper to the battery positive terminal.
That bypasses the regulator and shoots full power into the rotor. If everything besides the reg is good, you'll see a jump in voltage... a big jump.... like 15 to 18 volts.
Don't hold it there long... just long enough to read the voltage. Leaving it there too long and you might start frying stuff.

If voltage jumps way up, it indicates the regulator is bad (not sending enough juice to the rotor).
If there's no change, the problem is likely somewhere besides the reg.

All that make sense?

Yes, that’s my thought, to determine whether the unit is bad before I buy a new one. thanks Jim these are really helpful instructions,

Just one question, with the jumper cable in place, I should also remove this connection to the brush, or does it not really matter?

 

[Jim]

Just one question, with the jumper cable in place, I should also remove this connection to the brush, or does it not really matter?

I never do, you're only holding power there for a second or two.
If it makes you feel safer... it wouldn't hurt to just go ahead and disconnect the green wire (the hot one from the reg).
It'll still be a valid test with it disconnected.

 

[Grimly]

I made sure to grease the crankshaft

NO!

 

[Jim]

NO!

Yes. The tapered hole on my rewinds have been bead blasted and are rust free and dry as a bone. I always recommend cleaning the crank taper and smearing a little grease on there for corrosion protection.

 

[Grimly]

Have to disagree on that, Jim.
My tapers are spotless and grease free. There's no other way of making sure the metal surfaces bind properly. Grease effs that up.

 

[Jim]

Have to disagree on that, Jim.
My tapers are spotless and grease free. There's no other way of making sure the metal surfaces bind properly. Grease effs that up.

And I'll have to disagree. I'm constantly swapping rotors on my engine test stand. The crank has grease on it and I still have to use a puller to remove them. They stick on there just fine when greased. Even if they didn't, the woodruff key, lock washer and nut will keep it securely in place.

 

[D3viousd4n]

Hey again folks,

Sorry for the delay in updating, been carried away with work. Finally got to run the test Jim outlined above, and sure enough, when I connected the jumper wire voltage from the battery shot up to 16-17 volts, indicating a bad reg/rec.

Grateful to know where my problem lies, and thankful to all of you for the help. Very much hoping to have some more longevity and trust in my charging system after this. Unfortunately this reg/rec seems to have come defective from mikesxs (with a $100 price tag) and I’m not sure I wanna roll the dice with them again. Can anyone suggest a solid state type-b reg/rec unit for me to buy?

 

[Jim]

The ones you build yourself are the most reliable... and cheapest.

https://www.xs650.com/threads/diy-reg-rec-5twins-and-jim.55842/

 

[D3viousd4n]

The ones you build yourself are the most reliable... and cheapest.

https://www.xs650.com/threads/diy-reg-rec-5twins-and-jim.55842/

Awesome, I like it. I need to find someone to do some machining for me. Think I might take that aluminum plate you have in your rectifier bracket design and just expand it to be able to hold the regulator as well, then maybe stick the whole thing underneath my battery box.

I’m sure I’ll have some questions about the wiring once I get there. Hopefully in not too much time. It’s painful hearing the engine start up and not being able to ride lol

 

[D3viousd4n]

hey everyone, thought I’d put up a little update for anyone that might be following this thread.

I received all the materials I need for the diy reg/rec project linked above. I ended up using a website called sendcutsend to design a simple aluminum bracket to mount all the components to. I’m pretty happy with how it looks. It’s going to be mounted to the underside of the battery box located just under the seat on my bike, with a 90 degree bend so that everything sits perpendicular to the ground and gets good airflow. I think the vibrations are going to be pretty bad, so I’m gonna use some locktite on the components, along with some thermal paste on the rectifier and heatsink.

I’m about to start my work week so won’t be able to make much progress with wiring until next week, but hopefully with the guide I don’t run into too many mysteries. You know that song that goes, ‘the more I see the less I know’ that seems a pretty fitting description of motorcycle maintenance.

 

[5twins]

What's the thing with all the fins, just a heat sink? If so, I'm not sure it'll do much good where it is. I think it would be better if mounted on the back side of the reg and rec, opposite and directly behind them.

 

[D3viousd4n]

What's the thing with all the fins, just a heat sink? If so, I'm not sure it'll do much good where it is. I think it would be better if mounted on the back side of the reg and rec, opposite and directly behind them.

Yeah just a heat sink. I had a similar idea but the bolts holding the other components would keep it from coming into contact with the bracket, so no heat exchange there. I’m not super concerned about overheating. I expect it to get good airflow with how I’m planning to position it on the bike.

Here it is all wired up

 

[5twins]

I would flip all the mounting screws around so the screw heads are on the back side, then dill holes in the bottom of the heat sink to "swallow" the screw heads.

 

[650Skull]

I don't think the heat sink is necessary. The alumium bracket is plenty big enough for the bridge rectifier. When I done mine I bolted the reg on the battery box, (as per factory), made sure to earth to the loom or frame.

Don't like the idea of dust and dirt getting thrown up on the reg connection. Shrink wrapped the wires to the rectifier covering the connector as well

 

[650Skull]

Pics of my bridge rectifier I bolted under the battery box. I used 2 single phase rect they gave me a spare phase incase one cramped out. Sealed up with shrink wrap

 

[D3viousd4n]

I tend to agree the heatsink may have been unnecessary after all. Current ethos towards the project is that if it fits on the bike, charges, and is a sound circuit then I’m happy. Definitely not the most elegant design but I’m satisfied for a first timer with limited resources

Difficult to see in the pic but I do have shrink wraps on the rectifier connections, they’re just translucent all the connections and wire splices are soldered as well.