I swear progess is being made, but....

[Incubus]

OK, Succubus runs, she idles nicely, the petcocks and carbs combine to make sure gas stays contained within the bike when it is parked. I've made a lot of progress.

Now if I could only get it to charge. My XS runs very well until the battery wears down, then I limp home and coast into the garage.

I put my voltmeter across the battery after a fresh charge. It tested at 12.8 volts.

I started the bike and put the test leads across the battery. At idle, 1,000 rpm, it reads at 12.0 volts. Revved to 3,000 rpm it reads 12.0 volts.

I'm no rocket surgeon, but I'm thinking I detect a pattern there.

Here's what I've tried:

1. The battery is new.

2. The field coil seems to be OK. I have even resistance across all three wires and the brown and green test out at a resistance within range, according to the manual.

3. I disconnected the positive battery contact and put my voltmeter between the contact and the positive battery terminal with the ignition off. I get no reading.

4. I cleaned and polished both ends of the negative battery cable and the ground point on the frame. I cleaned the regulator/rectifier mount points and installed different cleaner screws and new lock washers to the R/R mounts. Is there another ground I need to look for? Does it matter which ground wire goes to the frame at the air cleaner top mount and which goes to the R/R? Are those wires both grounds?

4. I cleaned and polished the electrical connectors between the alternator and the wiring harness and the connections between the R/R and the harness.

I don't do a lot of electrical work. I usually call in my college senior son and make him do it. I'm paying a lot of money to get him that fancy computer something degree and computers run on electricity, right? And all I've ever asked in return for this benevolence is a little electrical work now and then and, of course, a retirement home on Kauai. Only those little things that every caring parent wants and deserves.

Is there anything else that could be wrong besides the R/R? I have no idea if this one is any good since the bike only yesterday was declared officially alive and a self ambulatory transportation device.

What else should I check before buying a new part?

As always, thanks in advance for your guidance and wisdom.

Patrick

[John]

If you should need a regulator, I may have one. Let me check, and get back with you tomorrow.

[Incubus]

I noticed something else I don't understand, and that perhaps is the root of the problem. I have two R/Rs, both of questionable servicability. Each has two wiring harnesses coming off, one of several wires and one connector with only one brown and one green wire. Yet, the two-wire connector plugs into a connection that has three wires - a brown green and a black. Black is the hot wire on this bike, right? Where does that black wire go? Right now it connects to nothing, but it certainly tests live.

My manual shows three wires coming off the R/R. I'm confused.

Patrick

[HobbyMan]

You need to check each of your regulator diodes. Sometimes if one or two is out, it may still charge. Half of the bikes that I bought this summer had at least one diode out. IMHO, the stock regulators are junk completely. On the bikes with good regulators, I am considering putting on geezer's unit because it is that much better and more reliable. Most people don't check each diode so they may not be charging as much as the bike is capable of doing. I have a ton of stock regulators that have at least one bad diode, some look really new. The Yamaha manual has the easiest procedure to follow in order to check the diodes.

[TopCatGr58]

Patrick,

Like Andrew said, the R/R is a weak link in our systems, and as Geezer has noted, they are not made with very robust diodes, and so they fry easily, and that's usually the cause of most charging troubles once you've ruled out the other connections!

That BLACK wire is a ground, but in the later years, they did away with it in the harness, cause they ground the unit directly to the frame, so that's why you have 3 wires on the R/R but only 2 on the matching plug! If you have an ohmeter, then the directions for the diode check in the manual is fairly straight forward. No absolute values to look for, just that they will be high when measured in one direction and low the other direction/reverse the polarity of your test leads. The values should be a factor of NOT less than 10x difference between low and high values!

If you don't have a manual to tell you which wires to check, here they are according to the colors.

Red, and it's opposing white(Same Plug)
Red and middle white
Red and end white
Red and brown(other plug)
White next to red, and the black in same plug
Middle white and same plug black
End white and same plug black

Then they just say the "B" wire, the manual was calling B1 the RED and B2 the Brown, but the last entry just says "B", so I'm not sure if they mean to check both the Red and same plug Black, and the Brown from the other plug, and the Black on the 6 wire plug!?

Perhaps Randy or someone else with Yamaha shop manual with same procedure can clarify this last wire check!?
T.C.

[HobbyMan]

Try that. I am lucky enough to have 3 manuals.
Sorry its kinda hard to read.

[HobbyMan]

(fixed resolution)

[jeffe]

Before my 78E had a major charging problem it still did not charge well. When It did start to get worse I bought one of the aftermarket ones from Geezer. It was a major improvement over the stock reg/rec. In IMHO even if you aren't having problems it worth the $100 or so to upgrade to one of his.

[Incubus]

OK, if I could walk y'all through a couple of test I performed, can anyone confirm my diagnoses? I did these tests based on the tech tip found here: http://www.xs11.com/tips/repair/repair32.shtml

Here goes:

1. Alternator, white wire to white wire, three tests. Resistance - .7, .7 and .8. Adjusting for the native resistance in my Craftsman multimeter by touching the probes together, which is .3, the readings come to .4, .4 and .5. Slightly high on one pair. Enough to indicate a problem?

2. Field coil (brown to green wire) 3.8 resistance. after adjustment, 3.5. Looks dead on.

3. R/R green wire to frame with ignition off - 11.9 volts. I've already established I lose A WHOLE VOLT through the ancient ignition switch. Anybody know how to fix that?

Brown wire to frame - .99 volts with ignition on, bike not running; 6.3 volts with bike at idle (1,000 rpm). Boy it starts easy now.

The readings seem to indicate to me that the alternator and field coil are good. The R/R readings look low to me, although my tach is responsive and the resistance readings across the rectifier read high one way and no reading with polarity reversed. T.C, I have trouble getting a reading with some of those other tests, but the bike strts great and, runs well until the battery starts to die) and the lights all work.

John, did I hear you offer an R/R last night? I'd really like to spring for one of Geezer's units, but I can't spare $100 right now. If I could I would already have bought carb holders. Suppose he'd accept a payment plan?

Thanks, y'all.

Patrick

[Snow]

You...uh...might want to check your alternator connector behind your fuse box...symptoms sound awfully familiar for some reason...

[Incubus]

I won't ask why, Snow. That connector is where I took the alternator and field coil readings. I cleaned the connectors before reconnecting them. They looked OK after I cleaned them. That's also where I took the readings for the green wire to the R/R, off and running.