'79 R65 Dies at Idle

[noah]

Here's the news: using the aforementioned method to jump the regulator by connecting the blue and black wires yielded the following results:

At ~ 1100rpm: 8.4v
At ~ 2000rpm: 12.0v

In general, between those two posts the volts went up with the rpms and visa versa.  At NO time did the volts approach anywhere between 13 and 15.  Then again, I didn't run it at anything higher than about 2100 rpms because I didn't want the engine to overheat.

I discovered a separate issue while running these tests.  The left piston is running much hotter than the right one.  I checked the plugs and the left one was jet black, while the right one looked fairly normal (white/brownish with some black spots).  Is this problem related to the charging system or something totally different?  Will a simple carb balance take care of this?

Thanks

[Ed Miller]

Ed, do you really mean "do have..." ?

I think it's complicated.  Sometimes the phrase "simple by choice" seems really cynical to me.  

Complicated doesn't mean it's not better than a permanent magnet alternator with a unit rectifyer/regulater, just that it's more complicated.

[Justin B.]

Hmmm...

[noah]

Now that we have the issue of the intended simplicity/unintended design shortcoming no closer to being settled, can we get back to the issue at hand???!!  Not to be pushy, and thanks everyone for the help, but its supposed to rain tomorrow so I'd like to get this fixed before I have to move the bike inside for winter.

The voltage reading at the terminals is waaay low, even with the regulator "jumped" by connecting the blue and black wires.  Also, the left side of the engine is running significantly hotter than the left.  Is this problem related or something different?

But first, what the hell does it mean when the battery is running low on voltage?   Is this a problem with the alternator rather than the regulator??  Bad brushes, as someone earlier suggested??  

Please, throw me a bone here . . .

[trolle]

I discovered a separate issue while running these tests.  The left piston is running much hotter than the right one.  I checked the plugs and the left one was jet black, while the right one looked fairly normal (white/brownish with some black spots).  Is this problem related to the charging system or something totally different?  Will a simple carb balance take care of this?

Thanks

Do a thorough check of the fuel lines, they must not be frayed at any points, check for airleaks. Check the plug cable connection, clean the plugs and change them. Check that the throttle cables have the same play at each side (appr. 1/20 to 1/15 inch when idling). Check that the choke is not hanging on either side. Take the bike for a ride and do at least 10 miles at 5000 rpm, stop and check the color of both plugs. If  you still get a black plug on the left side you have a problem with your left carb running on a too rich micture. Begin with checking the airscrew at the bottom of the carb: turn it to full stop and the 3/4 turn back. If you do this with the engine running you will hear the engines rpm change from slow - higher - slower. Stop at the highest rpm. Clean the plugs again, go for a new ride, check the color of the plugs and if the left still is black you will have to dismantle the carb, cleanse and adjust it.

Other causes for malfunction may be the ignition coil(s) or very rarely the connections from the "bean" can, but try the easy measures first.

greetings from a partly sunny north

[not-so-fast-ed]

I've also heard that side stand parking can cause oil to be trapped in the left cylinder head on bikes with a lot of miles on them.  Seems a bit "hokey", but who knows.  I usually park on the center stand so can't speak from experience..     :-/

Ed

[Ed Miller]

Noah, does your charge light stay on when the bike is running, especially at the higher rpms?  If not, is it burned out?  It should always come on when you turn on the ignition switch before starting the bike.  I have read that if that bulb is burned out, the system won't charge.  That, too, I find ironic.

Here's another article I found:

http://www.buchanan1.net/charge.shtml

I have never found a simple, step by step electrical trouble shooting chart for these bikes.  I want one but am not qualified to make one myself.  

[nhmaf]

Yes, the "GEN" light should be on when the ignition is turned on, prior to starting the engine.  do verify that it does this so that we know the bulb isn't burned out or broken.
As Ed mentioned, if the bulb never lights, you'll never get the proper charging behavior with the regulator and the alternator, particularly at low RPMs.

If the bubl does light brightly with the key just turned on, then we can look elsewhere.

Usually if a plug/cylinder has alot of oil in it, one will get heavy, ash like deposits on the plug, but if it is simply just black, thin deposits it is simply running (much) too rich.
Possibly the other cylinder is running much too lean - usually the leaner running cylinders run the hottest, unless things are so bad that you're literally still pumping unburnt gas  into the header pipes...

[noah]

This is beginning to sound like hell in a handbasket . . . the charge light works fine.  It comes on with the key in and stays lit when the bike is at low rpms and then goes out past around 1800 rpms, as it should.  

As far as the cylinder goes, the one that appears to be running richer is definitely the hotter one.  I still don't know what that's all about.  I prefer to fix the charging system first, and then mess with the carbs and everything else.  

Since no one seems to have any more advice regarding the electrics, does anyone know of a shop or mechanic in the Twin Cities that works on old beemers?

[MrRiden]

This is beginning to sound like hell in a handbasket

Nah, not even! based on the result of your test I'm gonna tell ya to slap the Voltage Regulator back in. You should have higher voltage readings [duh] next [step by step via internets is a sloooow process ya only completed one so far] is to isolate the trouble to either the Diode board or the Alternator Brushes. for this I'm gonna refer ya to the Haynes Manual Section 10.6 [see Haynes is good fer sumptin'] You either have a fried Diode or bad brushes. Thats it! one or the other [or dirty connections] but not an open rotor. Ya gots some other stuff goin' on there too but stick to the charging problem for now. If you decide to hand it off I'm afraid I'm not familiar with BMW shops in Minnesota [want some walleye with that?] BUT I do know of an excellent Britt Bike place that could and would point ya in the right Direction for a reputable BMW mechanic
http://www.britishbikerepair.com/
rich

[noah]

Ok, here's an update.  I pulled the diode board off and it looks ok to me.  Then again, I don't really know what I'm looking for so that might not mean anything.  I've attached a picture.  There was some rainbow-ish discoloration on the board at 2 of the contact points, but I don't know if this is extreme or just normal wear and tear.  I've attached a picture.  

I also pulled off the alternator stator (don't have the tool to pull the other part off) and checked the brushes.  They are not shorted than the wear limits in the Clymer manual.  They don't look terrible to me, but see above. I've also attached pictures.  Could it be that the alternator itself is shot?? It looks a little banged up, but what the hell do I know.  Is there a way to tell?

Feedback from everybody please, then, if we ever get this part fixed we can work on the lopsided engine.

[noah]

here are the alternator brushes.  Sorry for the crappy photo quality (the camera sucks) and the huge picture size (I'm as good with computers as I am with charging systems).

[nhmaf]

Apparently you may also have a VCR that is still blinking "12:00", but that's OK, we'll help you get through it  
(Couldn't resist the jab at the date/time stamp of pics)

Unfortunately, those pictures are pretty fuzzy _ I have a hard time trying to see any relevant details.  
Can you try to get one of the OTHER side of the diode board ?  Maybe try moving back just a bit further with the camera and it might be in better focus.
Things can get hot on that diode board, and sometimes a little discoloration is just that and nothing else, but from that side and the fuzziness of the picture it is hard to tell.
The earlier (pre-79) diode boards were more prone to sometimes "unsoldering" themselves due to heat, than the later ones.If it comes down to replacing the diode board,
one can obtain a unit that is considered better than the OEM unit AND for less money (how 'bout that !?!?) from several sources - the manufacturer is called "Thunderchild"
and will set you back about $95 or so.   But, we haven't reached that point inthe diagnosis yet.

Do you have a multimeter or Volt-Ohm meter handy ?  There are some resistance checks that you can do with the alternator & brushes but you'll have to put them back together somewhat to do this... I am trying to locate the info on how many ohms you should see measuring at different points of the alternator, but the bookshelf is not giving it up easy today..  before you removed the brushes, where the springs pushing them to make good contact with the slip rings, or could you see gaps ?    I think that anything less than 8mm or so on the brush length is too short/worn out, though the spring might be able to still keep things close, but not quite touching, at that length.

[noah]

No, strangely, the clock on the stove has the correct time and date.  It's just a single dial, which makes things much easier.  In any case, here is a probably useless picture of the other side of the diode board.  I'll also post a useless pick of the inside of the alternator, for whatever that's worth.

I do have a multimeter handy, but you'll have to hold my hand through setting it to read Ohms.  Tell the library I greatly appreciate the help, so take his or time with coughing up the info.  

The springs were on there pretty tight.  I think I accidentally "unsprung" one of them when I was pulling the brush out because I had to pull so hard.  I'm hoping the resistance will rebuild over time when I but the brushes back.  There didn't seem to be a gap, but I wasn't specifically looking for one either.

The brushes measure 1.5 cm (I'll ask the blinking vcr how many mm that is), which seems plenty good to me.   Google says that's 15 mm, which suggests brushes are not the problem.

[noah]

in case you still don't have a headache, here's the alternator: