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/
https://www.xs650.com/threads/wiring-in-a-70-79-combined-reg-rect-to-all-points-model-xs650s.52339/
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Swapping from PMA to stock charging (part 2)
- Thread starter D3viousd4n
- Start date
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?
Last edited:
Yes, the early bikes... the type B system. Your bike in other words.
D3viousd4n
XS650 Enthusiast
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?
Attachments
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.
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.
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.
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
XS650 Enthusiast
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?
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?
The ones you build yourself are the most reliable... and cheapest.
https://www.xs650.com/threads/diy-reg-rec-5twins-and-jim.55842/
https://www.xs650.com/threads/diy-reg-rec-5twins-and-jim.55842/
D3viousd4n
XS650 Enthusiast
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
