One of the corollaries to Murphy's Law is....
If it sounds like carburetion, then it has to be electrical ! 😛

Pull the front cover and disconnect the 3-pin connector coming out of the "bean can". If the white/ ivory connector on the end of the bean can is cracked, crazed, or simply disintegrates in your hand, then it's that connector making the ignition intermittent. (The harness connector never gives issues. It's always the white connector body.)

Broken Bean Can Connector Photo

To fix it, undo the screws holding the ignition canister to the motor. It will pull directly off the motor. You can then call Rick Jones at Motorrad Elektrik and he sells a replacement 8" pigtail with a new, much more sturdy connector. Working on the bench, you can solder in the new pigtail.

The can's drive only fits one way onto the crankshaft, so no worries about getting the timing 180° off. All you need to do is match the angular position of the ignition canister with the motor body before tightening the can's mounting screws. That's pretty easy if you go by the outline left in the dirt.

Hope this helps.

PS. I would not re-coat the fuel tank. The stock coating is doing no harm. Simply install a fuel filter on each side to catch the debris. Secondly, all the home-installed fuel coatings I'm aware of come off in ~3 years or so, leaving you with an even LARGER mess.

I have a new ignition from Motorrad. So I’m still thinking carb/fuel. Yes/no?

Thanks

In my experience, stock carbs don't just instantly stop working, then start working. That's electrical system behavior. Carbs will run lean and you'll have poor acceleration or anemic performance all around. The only way to get the "stop and go" you describe is to put some off-brand carb on the bike that is has the jetting way, WAY OFF.

• Try to see if the lights go dim or go OFF at the same time the ignition does. It could be a system-wide issue caused by the ignition switch, battery cables, or Starter Relay. Ignition switches do go intermittent. Both battery cables have independent, but system-killing connection issues. No one ever thinks to look at the Starter Relay because it's hidden under the fuel tank, but it is Mission Critical to entire electrical system performance.

• On another EI more common to British bikes, the transistors in the ignition module required 12.2VDC. When the battery was not in good health the system voltage would be dragged down below that threshold. The engine would then start to blubber... exactly like there was water in the fuel. This issue was easily diagnosed by turning the headlamp (the major power user) OFF, and the ignition immediately ran better. [Battery health was always due to poor charging or an out of date battery (no ability to "hold" a charge).]

I know you can't turn your HL OFF and still have ignition, unless you have the LH handlebar switch from the European models, but your symptom reminds me of this type fault. When you stop and wait, the battery (being a chemical storage device) has a voltage rebound. These bikes would re-start after a 3 minute wait and be able to ride another 4 miles. Then the voltage would "go low" again, and the whole process would repeat. Your stop-and-then-restart symptoms could be battery rebound related. Voltage readings taken from the battery posts [not running, running @ idle, running @ 3000 RPM] might be helpful.

Hope this helps.

Thanks for the ideas. I’ll check voltage. I have volt/ohm meter. Internet discussions are a pain...20 minute delays in the communication cycle. Anyway, not sure if the lights go dim. How do you check the starter relay? I have a manual. Sounds like I’ll be doing a complete electrical trace. Ugh

Thanks for the ideas. I’ll check voltage. I have volt/ohm meter. Internet discussions are a pain... 20 minute delays in the communication cycle.

Yes they are. Most of that is my fault. I'm an engineer and mechanic, not a touch typist. My grandmother urged me to take typing in 1967. "You'll need it" she said. "I'm going to be an engineer" was the reply. "I'll have a whole typing pool at my disposal." And here we sit at our computers, pecking away. So much for teenage foresight. 😛

Anyway, not sure if the lights go dim.

Well, you need to look. That tells you if it's an issue confined only to the ignition, or a electrical-system-wide issue... to which the ignition is only a small (but vocal) party.

How do you check the starter relay?

You don't. You replace it for $6.30 ! Amazon link

Dip the new relay's contacts into No-Ox-Id electrical conductivity and corrosion inhibitor compound, then plug the new one in.

I have a manual. Sounds like I’ll be doing a complete electrical trace. Ugh

With all due respect, you are getting WAY ahead of yourself. You don't even know what you're looking for, so you'll never find it. You need to define the problem first. You do that with testing, and isolation. Disconnect the headlamp and see if the problem stops. Do the 3 suggested battery voltage tests. By-pass the ignition switch and see if it stops.

For instance, what if your battery is not holding a charge because it's out-of-date, or simply needs water ?? Where is that in your manual ?

Hope these ideas help.

I didn’t mean slow typing. I meant the time it takes to send, receive, reply and then do it all over again.

I understand the isolation. Intermittent electrical issues are hard to pinpoint

I just need a super sized wiring diagram. 67 year old eyes require help.

Yes I took a typing class but I still ‘hunt and peck’.

Oh. The bike doesn’t stall out. Just runs rough for 1 to 2 minutes. Then normal agsin

I didn’t mean slow typing. I meant the time it takes to send, receive, reply and then do it all over again.

No, I assure you that's me. It takes me about an hour to compose and type what I consider to be a meaningful reply.

I understand the isolation. Intermittent electrical issues are hard to pinpoint.

Yes they are. I had to keep riding mine. Then one day, the starter button became intermittent. It wasn't until I checked the starter relay that I discovered that all the power for the bike ran through the relay terminals. The relay and the relay socket were both toast.

Ok...took the carbs apart, cleaned jets, checked float level, inspected diaphragms, replace starter relay, (yes I know two changes won’t pinpoint issue) blewout gas lines, pulled plugs, right one a bit lean compared to the left, put it all back together and went for a 75 mile ride (60/70 mph). Seems to be working. No issues. I’ll know better with a longer trip. I did notice the metal bracket between the two floats was a bit bent! (Right side carb). Fingers crossed, on the road again!
Thanks

Different color plugs can only be from poor carb sync, float issues, or dirty jets.

Different color plugs can only be from poor carb sync, float issues, or dirty jets.

Different color plugs can only be from poor carb sync, float issues, or dirty jets.

Different color plugs can only be from poor carb sync, float issues, or dirty jets.

More when I can get off this stupid iPad.

The ignition timing is the same on both sides. The air filter is the same for both sides. It's fairly hard for the compression to be that different from side-to-side. That pretty much only leaves the following to account for unmatched plugs...

Carb sync
The slides may not be rising at the same RATE, either due to being mechanically out of sync, ripped CV diaphragm, or some other mis-match.

Float issues
BMW suggests you get the latest floats and float needles which are ethanol resistant, unlike the OEM floats. Then check the levels with the new floats.

Closed-up jets
Ethanol can leave a thick varnish on anything submerged in the fuel. This coating would obviously have one side running leaner than the other.

Air leaks
Air entering the intake after the carb, but before the cylinder head, such as cracked intake hoses.