lost spark in heavy rain

[23580]

I have a 1977 R100/7 145k miles with a Dyna 000 ignition twin plug. I have riden this bike in severe weather many times before, I had a complete failure this weekend in heavy rain. I lost all spark in the rain was towed home and the next day ofcourse the bike runs just perfect. This is an old setup probably 22 years and 20k miles. The Dyna box reads Dyna 000 any sugestions. I was thinking to just upgrade to newer unit but which unit do I go to.

[crazydrummerdude]

I believe this is a symptom of cracked coils.

[Rod Sheridan]

Coils, spark plug leads and caps, and spark plug wires.

Regards, Rod.

[Bill Burke]

Do a cap to cap test using the ohms scale on your multimeter. Should be in the neighbor hood of 23K ohms plus or minus. If ok, then disconnect neg cable and remove the front cover to examine the watertight integrity of your "points cavity" with the Dyna unit in there. Is the little gasket still intact?

[Polarbear]

My R100/7 has 300000+ on a Dyna3 system now and is perfect still, so they last a long time. Bill has the right idea again. Coils fail, but very rarely. The front cover inspection is a good one and plug wires, but all are not likely to go bad at once. A central system failure has occured and the front cover area is a best bet to look see:). Check the ground of the Dyna3 system first:). Randy

[amiles]

I'd try the plug wires first and resistor caps next. This is the easiest and least expensive potential equipment solution for the problem. Wet non functioning wires that magically work when things are dry are a pretty common problem.

Don't forget that the wires deteriorate in just a few years and are more exposed to the rain than the other parts.

[jdmetzger]

I'm going to join in on the suggestion to check the plug wires. While riding home my new to me R100GSPD, I lost half spark after heavy rain and really had to fight to get it home. About 15 miles from home I got my power back, and even with a garden hose I couldn't replicate the issue. I checked coils, ignition modules, etc, but to no avail. I replaced the wires and rode it, though I was always nearing panic attacks when it looked like rain. Finally in October (over a year later) I hit a rainstorm for about 1.5-2 hours and all was fine. The wires LOOKED ok, but clearly they were not.

[114298]

Heavy rain will short out older style or cracked spark plug caps/wires.

This happened to a friend of mine on a ride (90/6) and he was convinced something was fatally wrong.

I pulled out a lighter, heated up the spark plug cap, drying it off and the bike fired up just fine....in the rain. Electrical tape sealed the connection for the rest of the ride.

He ordered now plug caps and wires....good to go...even through a river let alone a hard rain.

[23580]

innresponse to the r100/7 which broke down due to heavy rain I am new to this section so be kind. We removed the front cover, and as I sort of expected there was quite a bit of residue from water within the small cavity where the electronic pickup is located. I ordered a new seal but also belive some of the water was coming in thru the wire harnness which exits out the top of the front cover. We will be sealing this area with RTV silocone P.S. the wires are new lats year, the coils even when soaked yesterday with a jug of water did not sputer at all. thanks for all the great replies.......

[3moskvichi]

I'd bet it's the coil. Here's a photo of my stock coil after 20 years. Note the two prominent cracks. Symptoms at time of replacement were stumbling at idle, but generally ok at all other rpm. What confirmed it for me was taking off the tank and running the bike at idle outside in the dark. I could see sparks arcing, and their timing coincided with the engine stumbling, plus I could hear the arcing, sounded like a slight ticking.