Suddenly rough, dies. Then problem disappears.

[pswanson]

I've been trying to fix this problem for a few years. At first it wasn't so bad, but now it's so I can't trust the bike to go far. Its an 89 R100RT which otherwise has been a great bike (apart from the electrical system of course). Generally it runs great. On the highway suddenly it will act like it's running out of gas, then a few miles down the road, power returns and it's usually fine for the rest of the journey. Around town it's running fine, then suddenly and progressively runs rough, until it won't idle, backfires, has no power. I can usually get it started after it dies completely and give it all kinds of gas until it seems to sort itself out, then it runs fine again. It can't be consistently getting dirt or water in the system. I've had every part of the fuel system completely stripped down and replaced the floats. Everything looks good. I haven't replaced the diaphrams, if I remember correctly.

But why would it run fine most of the time, then keep letting me down over and over again. I'm ready to believe the bike is maybe possessed or something. I've replaced the plug wires and virtually the entire charging system over the years. Has anyone else experienced and solved this problem? The inconsistency of it is driving me NUTS. The bike is supposed to be this ultra reliable machine, but so far it's been one thing after another.
What do others mean when they speak of the 'Can' -- sounds like it might be the cause from some of the other posts.

Thanks!

Paul

[beemerguru]

The ignition canister...the silver round thing inside the front engine cover. Your symptoms are the usual signs of the impending demise of the sucker. Runs, sudden cut offs and restarts, backfires, etc.

Call Rick at Motorad Electric for a rebuild unit,,spend a half hour replacing it and setting the timing and worry about it again in another 100-150K miles.

[lightning]

Gotta be ignition. If the canister doesn't solve the problem, then perhaps your ignition wire is loose or weakened.

[pswanson]

Thanks, I'll follow up on your help. I've just taken out the coil, it's grey, and I do see two cracks from the core out to the wire receptacles. For the cost of a new one I'm guessing I should go ahead and replace it as well.

What about this heat transfer paste I apparently was supposed to replace 4 times already since 2000??? Is this for the black unit just ahead of the regulator? Do I just smear it all over the unit or something? It's never had any on that I've seen. Any pictures or diagrams I could see somewhere? Thanks!

[GlobalRider]

I've just taken out the coil, it's grey, and I do see two cracks from the core out to the wire receptacles. For the cost of a new one I'm guessing I should go ahead and replace it as well.

I once diagnosed your exact same problem. A guy in upstate NY was just heading out to the Finger Lakes Rally in heavy rain when 15 or so minutes later he returned with the thing bucking and snorting.

While they ran off to a local car parts outlet to get ignition wires, I was left with a DMM to do some testing...the coil produced some varying numbers and sure enough, upon removal, I found a crack in the coil housing.

BTW, a simple test you can perform if the bike dies on you and if you suspect the ignition is to carry a spare spark plug along. When it dies, pull a plug cap and insert the spare spark plug holding the casing to ground (top of cyclinder head). With the ignition now on, flick the kill switch on and off several times. If you see a spark, your coil, coil wires and ignition module are fine and your "ignition can" is suspect...all that info in under 30 seconds.

I also found one of the pins (wouldn't you know it...the kill switch wire pin) not seated and locked/snapped into the wire connector housing that attaches to the ignition module. I was sensing a slight hesitation shortly after having bought the bike new and traced it down to that. It ran fine after that.


I've just taken out the coil, it's grey, and I do see two cracks from the core out to the wire receptacles. For the cost of a new one I'm guessing I should go ahead and replace it as well.

What about this heat transfer paste.

The only place I can think of using some is between the ignition module and the heat sink which is mounted to the frame under the gas tank on the right hand side. Clean any corrosion off between the two before applying a thin coating of heat sink compound. Wipe off the excess after the two are bolted together.

[pswanson]

Awesome, thanks guys. I've ordered a new Coil from Euro MotoElectrics for $129 and took the forum advice to also replace the ICM with the updated one that has some built-in protection for the coil for $42. Anyone with a classic Airhead who hasn't checked the coil to see if it's gray or Black should do so -- for what it's worth, change it now and save the grief of wondering what has possessed your bike...

If that doesn't solve it completely (along with cleaning / checking my connectors under there) I'll go after the "can". Sure hope it's not that though. Paul

[lkchris]

Gotta be ignition.

Nah, could be as simple as his tankbag sealing the air vent at the gas cap.

The BMW ignition system is dead reliable and usually the last thing that's the problem.

[lightning]

Nah, could be as simple as his tankbag sealing the air vent at the gas cap.

The BMW ignition system is dead reliable and usually the last thing that's the problem.


Why didn't I think of that!

[108625]

Pswanson,

Has it ever completely stalled, or is rough running as bad as it's been so far?
Does it seem like both cylinders are doing this the same, or just one side, and if so is it consistently the same side.
Have you ever checked fuel and spark (on each side) when it's acting up?
What does you tachometer do when it does this, and for that matter, what does the rest of your instrument panel do?

What I'm getting at is you've had this problem for years, and you just ordered parts to fix it without really knowing what the problem is.
It could very well be the coil or can, or it could be a plug wire or cap (cheap), or a fuel vent (free) or other possibilities.
At least when you get your parts, can I suggest only replacing one at a time, so you can out which one it was, if either.

Just my two cents (I hate an unsolved mystery)
Bob

[pswanson]

The trouble seems evenly distributed on both cylinders -- both run like crap when it happens :) I pulled plugs off alternatively to see if it was mebbe one of the cylinders not firing with no more effect on one than the other. BTW -- I also now learn NOT to do that EVER on the electronic ignition bikes. The coil (gray one) is cracked, so I'm replacing it. The advice I've read is to also replace the updated ICM for the new (black) coils, so for an additional 42 bucks I'm gonna. Apart from that I've not replaced anything yet. I understand the caveats of replacing parts "just to see". The cracked coil can test out OK when cold and dry, but absolutely fail when hot or wet, which is exactly the symptom I'm having. I've already cleaned and checked the entire fuel system -- won't go into detail there, no reason too. The bean can may be the problem after all, but I'll see once I've replaced the coil. If the intermittant failure disappears then there's no reason to suspect a bad can in this case.
Thanks!
Paul

[rocketman]

I started having similar issues on my 78 airhead (converted to electronic ignition) for several months. At first I too went over all the electrical and ignition systems, still an sometimes yes and sometimes no situation.
Then I took the tank off and cleaned it and pulled the petcocks off, low and behold, gummed up screens. cleaned them and put in new gas, and haven't had a lick of trouble since then. Go figure.....

RM

[108625]

Sometimes we do solve the wrong problem.
My brother bought a '91 Chevy truck from a guy who was convinced he needed a new engine. He bought it, transferred all the hardware over and installed it. When he started it up and it still ran rough, he tried tuning a while, and in frustration gave up and sold it to my brother for a song (complete with warranty on the new engine). My brother took it home, spent a few hours troubleshooting, and replaced the distributor for $70.
It still runs like a champ eight years later.

It's great when someone comes on here with a problem and someone says it's part X, and they're right. But asking a few questions about troubleshooting and getting the answers helps a few more of the rest of us figure out how they knew.

[JETHRIDGE]

I had the same problem wiith an 83 RT. Running great and then it Would die for a sec or two and bump start and run fine until the next time. Only one time did it not run long enough that i pulled off the st and then it started up right away.
I was told to remove the tank and un plug every wiring conection possible, clean width Electronic cleaner and re conect the wires. Spray the cleaner down in the ones not disconected. One more step. Pull the tow fuses in the headlam bucket and clean the ends.I did this and have never had a problem sence. This may not solve your problem but it could prevent one latter on.

Jack
Ocala Fl

[Polarbear]

Coils almost NEVER fail and I've seen none fail in my 40 years and BMW's. Maybe you have one, however so be it! They sure are easy to check with a good ohm meter:). You have a 20+ year old Beemer, so check the "GROUNDS" everywhere on the bike, including the "battery ground cable". which goes so unnoticed by sooooo many owners of these bikes. If you have yet to do the carb diaphrams and did everything else, I'm confused you did a half a** job. The diaphrams go a long long time, but you did everything else? Its not likely "both" diaphrams fail at the same time, so don't worry too much if you say both cylinders fail equally. Most probably a ground issue in the electrical system. I'm nearly "positive" of it:), from what I read so far. Randy, Happy Trails:thumb :usa

[pswanson]

Wull, let me tell y'alls, seen as how I bin readin so many gall darn posts, including [mycotropic;365178], bemoanin the crackin of them there GREY coils, describin simptoms zactly like mine, hell I'm just gonna chenge thet sucker fer one dem newfangled BLACK coils wut I hear BMW up n improooved upon, n see if she don' jess fix it. Seen as how the GREY coil I dun pulled outa der IS truly cracked dyagonally right up from the cenner over to each uh the wire reeecepticles. Seems smart enuff, but hell whata I know -- beein a Systems Analyst and all, trubble-shootin stuff fer a livin fer aboot the lass 20 years -- hell -- chek for fuel, chek for spark, chek for air -- the 3 essenshial requirments of the inturnal cumbustion engine? -- who'd uh thunk it!

Seriously though. Perhaps there has been some confusion because of my initial posting. I didn't replace almost the entire electrical system trying to solve this problem. I replaced each component, one by one over the years, because one by one each component FAILED. Here's the rundown.
- Bike stops charging:

- I identified shorted windings in the rotor -- it was dead. Had it rebuilt. 3 months later, the rebuilt rotor died. Purchased new rotor. (Don't waste your money on a rebuilt). I Spent $500 instead of $300 trying to save $100.

- Starter siezed.
- Rebuilt Starter. It's been great since.
- Replaced plug wires $ plugs.

- Bike stops charging again.
- Identified the Diode board is culprit. Ground wires are frazzled, diodes shot.
- Replaced Diode.
- Too much Charging!
- Replaced Regulator. Now Charging is perfect.

- 3rd YUASA battery begins letting me down.
- Replaced with Odessey PC680. Heaven!

Now, regarding THIS problem:
- I have dissassembled and cleaned the petcocks and screens, ensuring there is no red inner fuel tank coating or silt etc. clogging the filters.
- Ridden with the cap partially open, ensuring no vapor lock -- problem still occurred.
- Replaced the fuel lines. (Old and cracked).
- Dissassembled and cleaned the carbs, and replaced / adjusted the floats.
- Checked the diaphrams for pinholes.
- Disconnected and cleaned and reconnected wires under the tank, and connections to all lights, and replaced burnt bulbs in gauges. (Will do this again, this time with electrical contact cleaner, oxidization preventer).
- Replaced the ground cable bolt with self-tapping metal bolt since original female threads were stripped preventing a tight connection.
- Replaced the air filter at the previous oil change. It was due.

It's good advice I got, about the coil and/or the bean can. I'm going to change the coil, and put the new upgrade ICM in for good measure. If the problem continues, I'll tear down the fairing, front cover, and do some diagnostics on the bean can. However if after replacing the coil, the can ain't broke, I aint gonna fix it.