Coils

[mykat]

Is it unusual for a coil to fail for only one cylinder?

My #3 and #4 cylinders have both started randomly dropping during idle, after warm-up. Feels like they're fouling out, and they will randomly fire on and off again during cruise. Does not happen consistently.

I haven't gotten the tank off to check connections yet, but I'm wondering if it's unheard of for a coil to stop working for only one cylinder.

Also, I did wash the bike about a week ago, noticed the problems probably started happening shortly after that. Coincidence?

[shift6]

I do not think its a coincidence if the bike was running good prior to you washing it. I would pull the tank off, and check you wires / plugs, ensure everything is tight.

And this bike has 4 cylinders but only 2 coils, I believe cylinders 1 and 4 share a coil, then 2 and 3 share a coil, so I do not believe you have a coil going bad.

If nothing seems out of the ordinary, then you could be having a carb issue.

[Kreylyn]

Clogged drain holes for the spark plug wells could cause water build up that would facilitate arcing and grounding out before the plugs could spark.

I would check those... and the wires, plug boots for damage (not from the water, but the water would cause damaged wires to arc more....)

Krey