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Old 05-31-2010, 06:16 PM   #1
Gray Dragon OP
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Smokin' Airhead

Ok a couple of weeks ago I fired my '82 R100RT up in the rain. It started normally but I noticed what I thought was steam come off the front of the engine (I now realize it was smoke). The bike ran fine and I rode it for about 15 min. About 30 minutes later I started it back up and it ran rough that got progressively worse then died and would not restart. After sitting a few hours it ran for about 5 minutes before dying. I checked the gas for water and it was clean.

I did some searching and found references to the diode board. I pulled it out and had it checked. The electronics gurus at work said it checked out (as far as they could tell). I did notice a lot of oxidation on the contacts and cleaned them.

Put everything back together (including the front cover which in hindsight was a bad idea). It fired up just fine for 90 seconds at which point white smoke poured out of the front cover and the engine died.

I'm about to the limit of my knowledge. It turns over, and has good spark. The way I understand it the diode board is only part of the charging circuit. I'm thinking the Ignition trigger unit since it is in the same location as the diode board, but would like to get some other opinions before I tore into it again.

Thanks
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Old 06-01-2010, 05:08 AM   #2
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Did you disconnect the battery before installing the front cover? You would know right away if you upset the electron community. But you say it has good spark so either gas or timing would be the issue.
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Old 06-01-2010, 05:25 AM   #3
robsmoto
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Snowbum (aka Bob Fleischer) is considered an AirHead guru. He has a lot of information about Airhead bikes, including electrical issues. I think that it was he that indicated that an electrical part has failed when the smoke gets out. See -

http://bmwmotorcycletech.info/

The OP indicated that he had little knowledge about the bike's electrical systems. A recommended and inexpensive source of information (and good source for replacement parts) is Motorrad Elektrik -

http://www.motoelekt.com/

The wiring diagrams and charging system book are good to have -

http://www.motoelekt.com/goodstuff.htm
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Old 06-01-2010, 08:25 AM   #4
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For once I did remember to disconnect the battery.

Thanks for the links, I'll check them out.
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Old 06-01-2010, 03:55 PM   #5
Wirespokes
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If smoke got out, I'd think scorching would be visible.

Was anything blackened?

As was mentioned recently in another thread, for an engine to run three things are needed: fuel (air/gasoline), compression, spark.

They're needed at the right time in the right amounts - at least in sufficient amounts for the process to occur.

So the first step is to verify they're all there - don't worry about how much or when, just if they're there.

A simple place to start is spark. Once it stops running, pull a plug and ground it to the head with the plug wire connected and crank the motor looking for a spark.

Eliminate things one at a time.

Your symptom and situation are so general it's difficult to come to any logical solution with the broad data available. More data is needed.
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Old 06-01-2010, 09:11 PM   #6
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[Background noise, people murmuring]

[Speaker] Attention, Attention lets get this meeting of IA (Idiot's anonymous) started. I see we have a new member. Would you care to stand up and introduce yourself?

[Gray Dragon] Hello, my name is Gray Dragon and I'm an Idiot. I'm an idiot because I can't tell when my bike is really broken or just out of gas.



Well I'm not sure what the original smoke was from, because I didn't find anything burnt looking. After I switched to reserve it ran fine and I was able to trace the smoke to the exhaust cross over that had oil/WD-40/penetrating oil/electric contact cleaner/etc on it.

I'll do a more through inspection tomorrow in the daylight. In the meantime I want to thank everyone for the tips and ideas.

Thanks

Kevin
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Old 06-02-2010, 05:23 AM   #7
bpeckm
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mea culpa





mea culpa






mea culpa.....


Done! You're a free man....

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Old 06-02-2010, 05:55 AM   #8
Stagehand
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Is there a front crossover exhaust tube thats leaking? Maybe rusty and has a hole, or has come loose... big air leak?

try and run the bike with the front cover off, and see if you can see where the smoke emanates from.

Its really smoke, eh, and not steam or anything?

Is it oily smoke? like youre burning some oil off?



Holy crap I should read threads more carefully before posting

Carry on
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