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Old 05-12-2014, 07:12 PM   #1
Babbitt OP
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Trouble idling in the rain

Today coming home from work in a light rain my 92 R100 GS would not idle. Every time I stopped I had to keep the RPM's above 2,000 or the bike would cough and die.

When dry it runs great.

What should I check?

Thanks
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Old 05-12-2014, 07:17 PM   #2
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First guess is poor spark plug wires: you can spray them with some WD40 or other water-chasing potion, and try that. You might have bad electrical connections... if spraying helps, get some new wires!

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Old 05-12-2014, 07:40 PM   #3
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And second thought is the coil. It can develop hairline cracks which can cause wet-weather problems.

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Old 05-12-2014, 08:50 PM   #4
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Thanks I will start with WD40 and see if that helps.
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Old 05-12-2014, 08:56 PM   #5
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Eek

I've used dielectric grease to rub down the wires in a pinch.
If the wires or coil are original, it's probably time to change them. My stock Bosch coil caused all kinds of trouble.
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Old 05-12-2014, 09:06 PM   #6
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And, just where exactly is "the Group W Bench"?

You know, even though it sounds snappy, it doesn't help us at all. We use the location in your profile to help you locate parts or others to help, and also provides more data to help with problems - like is this at higher elevations? Did it get cold when it rained? The climate is different from Arizona or high in the Rockies where it might have come close to snowing today.

The more data we have, the closer we can get to an accurate answer for you.

It's true, the most logical first choice given your situation is a high voltage leak to ground due to poor insulation. A cracked coil qualifies in this category. But there can be other sources as well.
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Old 05-12-2014, 09:27 PM   #7
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My '76 R90/6 was doing this very thing, and it was the choke gasket on the LH side. I replaced it, and all was good.
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Old 05-13-2014, 04:12 AM   #8
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Quote:
Originally Posted by Wirespokes View Post

The more data we have.................................
Man, I just saw your location, enough data already.
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Old 05-13-2014, 06:57 AM   #9
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The group w bench is a reference to the Arlo Guthrie song Alice’s Restaurant.

I am just west of Minneapolis, MN it was about 55 F with light rain, I noticed the problem about 20 minutes into my commute home at a red light. This morning with the bike dry and a dry 45 F for the commute in to work it ran fine. The spark plug wires are not original but they are not new either. Short of using a hose what is the best way to check the wires and coil? I could not see any cracking but that does not mean it was not there. I hate to just start replacing things, both because I am cheap and because I don’t want to create a new problem by screwing something up.
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Old 05-13-2014, 08:00 AM   #10
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You can sort of check the wires if you have a VOM or a Multi-Meter. Something that will check Ohms. Do you have molded rubber plug wires, with the plug socket and wire all in one piece? Or metal cap plug wires? The resistance of a '92 bike's plug wires should be 5000 Ohms for each plug wire. But some GS's had the early metal caps used, I'm not sure how BMW did this since the metal caps only had 1000 Ohms? Maybe this is explained more in one of the manuals. Do you have a manual?

Also when you check this resistance you will want to flex or bend the wires to see if the Ohms reading changes and maybe squirt with a hose?

That's all I can think of as far as trying to check the plug wires. They may check good tho and still be the problem. It's not an easy call and sometimes you gotta Bite the Bullet and buy some new ignition parts. Hopefully actually, you replace bad parts before they strand you.

Carefully check the coils for cracks and carbon tracks. There have been problems with the coils but I don't think this year is a particularly bad year for coils.

There is also a module as part of the ignition system. This is mounted against a heat sink and has a special heat sink paste to be applied regularly. I think I've heard you need to apply new heat sink paste once a year? You can buy the paste at a Radio Shack or numerous places online.

Please ignore any comments about the paste not being needed. BMW put it there so you should use it.
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Old 05-13-2014, 08:21 AM   #11
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+1 to dialectic grease. I had the problem on my vstrom while riding in the rain, so I removed the rubber cap around the spark plug, squirted a whole bunch in and around the cap and closed it back up. The problem never came back even after many a downpour. Yeah yeah, it isn't a bmw
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Old 05-13-2014, 10:06 AM   #12
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I'm going to throw my money on the ignition coil being the culprit.

Quote:
I hate to just start replacing things, both because I am cheap...
Well then here is your answer: http://www.ebay.com/sch/i.html?_nkw=31614-83A&_sop=15

I've had one of these in my airhead for years (as have many others) and it's been flawless.

nothing screwed with this post 05-13-2014 at 10:13 AM
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Old 05-13-2014, 11:25 AM   #13
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I would throw money at a new set of plugs, caps and wires.

And I would pull the petcock and check for debris.
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Old 05-13-2014, 11:59 AM   #14
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Try this: next damp day (well, night actually!) when it is dark out: start the bike and look for little blue arcs around the plug wires and the coils.

Thinking about it, coils are prone to cracking and fizzling, but if it is only a light rain, the coil IS somewhat protected.

Cheap enough to replace plugwires and caps... try these: Motorrad Elektrik or Euro MotoElektrik

Try spraying with water-displacing whatever, your local auto supply place will have a fine selection of spark plug / wire sprays from Gunk, CRC, WD40 etc.

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Old 05-13-2014, 08:21 PM   #15
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Seriously, sportster coil? that just seems wrong

I will look for the blue sparks that is just cool. I will also try the wire test.

It might be time for new parts, it is not a KLR afterall.

Thanks everyone.
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