charging

[GLoweVA]

good to know that the yellow wire is supposed to stop at the plug, wonder why it's there in the 1st place

The 78-81 share the same stators so it's wired that way, only the 78-79 use the yellow wire further in the harness to drive the headlight relay.

[crazy steve]

Phil's test will tell you if the 'regulator' part of the 'regulator/rectifier' is bad; if you get full output, that 'proves' the alternator and diodes. Of course, you still have to replace the whole regulator....

That yellow wire is in all the alternator field coil leads, but only goes beyond there if you have a '78-79 bike (where it powers the headlight relay).

98% of the time (a little hyperbole here, but not much! ), the problem is poor connections in the alternator wiring. Making sure these are all clean and tight most times will clear up poor outpit. Look here: http://www.xs11.com/forum/showthread.php?t=35339 ... for how to check the connections. If you have poor connections, any other tests you may do won't help, so make sure these are good first. If that doesn't clear it up, then proceed to the other tests.

[Elwood2]

Undo all the connectors to the regulator.
The manaul says to check white to red and white to black.
Check with meter on ohms (at least 550ohms)
Black meter lead on the red connector and red meter lead on the white connectors. (all 3 should be about 500ohms)
Red meter lead on the black connector and black meter lead on the white connectors. (again all 3 should be about 500 ohms)
DO the reverse and you should see an open for all six of the checks.

I just checked this with the one I got in the mail. all good.

every wire combo off the 5 wire plug on the regulator came back with an open reading.

[cywelchjr]

I've seen over +15VDC doing this test at 5K RPM's, the regulator will not limit the voltage at all with that wire grounded, I can't tell you (don't know) the specifics of why. It pretty much just determines if your alternator is bad or if your regulator is weak/bad.

If the voltage comes up it tells you the regulator part of the regulator/rectifier is bad, if it doesn't, either the alternator is bad or the rectifier portion of the regulator/rectifier is bad, mine when bad didn't do anything with that test, but replacing the regulator/rectifier fixed the problem because the rectifier was the part that was bad, which based on the readings sounds like may be the problem. Now something to be aware of, they CAN test good and still be bad, as they can test fine with the tester under the very low voltage the tester uses to test the solid state junctions of the diodes in the rectifier bridge, but it can fail under the voltage and current load of normal operation, this is what mine was doing, all the tests said nothing was wrong with it other than the fact that it wasn't working, but replacing it with another unit fixed my charging problem, this is however rare, most of the time the rectifier bridge if bad will actually test bad using the test in the FSM.

I've also seen several alternators with the windings significantly higher in resistance than the spec (more like 15% above rather than the 10% allowed) and still work perfectly, but I've never seen one in spec that didn't work, the field coil being in spec is FAR more inportant than the stator coil, that one IS important that it be within the spec as stated in the manual.

[cywelchjr]

every wire combo off the 5 wire plug on the regulator came back with an open reading.

That sounds like the rectifier bridge is burned out, meaning you need a replacement unit, I paid $15 for mine almost 3 years ago and it still works as good as the day I installed it almost 30,000 miles ago.

[GLoweVA]

Rectifier

Elwood, I saw one on ebay right now.
The seller is in Portland, OR.
Buy in now price $14.99 + $6 s/h.
Great price.
http://www.ebay.com/itm/79-80-81-YAM...-/261051817206

[Elwood2]

I bought the one from the link you gave me. Then when reading it I see he has it listed as a cdi. So I emailed the seller hopefully he listed it wrong. Cause I asked for a refund if he posted the wrong pic.

[GLoweVA]

The pic shown is of the rectifier. He also is selling a cdi, so maybe he just mixed up the listings.

[sparks]

Not sure if you got your parts yet but this guy is near Portland Or and makes rectifiers/regultors.. You may give him a try.. http://www.oregonmotorcycleparts.com/

[Elwood2]

He emailed me back to let me know it was a typo and I bought the regulator.

[Elwood2]

Not sure if you got your parts yet but this guy is near Portland Or and makes rectifiers/regultors.. You may give him a try.. http://www.oregonmotorcycleparts.com/

Yes I looked at them and would love to get one but money is very tight so I went with the $21.00 one including shipping. From what I have read the ones Geezer sells are alot better then stock, and when I finish school and get back to work I do plan on getting one.

[Geezer]

I hate to tell you this now but all the diodes reading open is usually a problem with how you're using the meter. With digital meters you have to use the diode check function not the resistance scale to test a rectifier or you will get a false fail on all tests.

Geezer

[Elwood2]

So I got the new regulator today. And I have the same results. I tested the voltage to the battery and it stayed at less then 12volts even reving up the bike. Next I pulled the headlight, tailight, and blinker fuses and started the bike. With those fuses pulled the tach did not work also. Anyway it was at 11.96 volts at idle and only went up to 12.5volts while reving it up.

[crazy steve]

If the alternator coils check correctly for ohms, make sure the connections to the stator are clean and tight, both the plug at the regulator and particulary the one behind the fuse panel. I hate to keep harping on this, but charging system problems are nearly always caused by poor connections...

[GLoweVA]

+1 on what Steve said. If the tach isn't working, and it gets its signal from one of those white stator wires, then it sounds like there's an open connection somewhere there.
Try again reading the stator ohms from the plug at the rectifier pulled. White to white to white, should be about 1 ohm. Also check those 3 to ground to see if one of them might be shorted to the frame.
I'm thinking that maybe if one of them is grounded out then the tach wouldn't read and the alternator output of course would be much lower because you're only working with 2 of the 3 stator outputs.

I'm getting a little stumped on this one. Maybe time to start from the begining.