Waterproofing the bike

[Kookas]

One of my cylinders cuts in and out in very heavy rain. It's been like that since I had it (bought it last August), but I hadn't experienced it in ages until we had today's torrential downpour.

The obvious thing to look at are the spark plug wires and boots, but I feel like I looked at them the first time I experienced this and saw nothing.

I'm going to look at them again this weekend (it's an F so every little engine job has the added step of 'remove the fairing' which makes me lazy on weekdays), but a few questions:

• Can cracks be microscopic?
• Is there some kind of way to test for a crack?
• How can I even figure out which side is cutting out?

It must be something really small, because the bike never has an issue in ordinary rain. It's only in flash-flood type rain that it starts acting up.

Oh yeah, also, it's not limited to when the bike is cold. I thought that engine heat would solve water issues. However, it did seem like the cylinder stopped cutting out when I revved the engine hard enough. It only did the cutting in and out thing at idle and coming off idle. I had to rev the nuts off it to move away from a traffic light, but once moving I was ok.

[Kilted1]

It's probably still doing it at speed, but less noticeable since the other cylinder is making more power. 

The boots on the plug wires don't have to be visibly cracked to arc out. If it did it once, it left a carbon trail that's now conductive.  The more it happens, the more it's likely to happen. 

You can let it idle in the dark to observe the arcing.  Or you can just replace the plug wires and be done. (Unless it turns out to be something else of course.)

[Kookas]

Little update on this. It almost left me stranded yesterday evening, so when I had finally managed to limp it back home, I had the fairings off and checked it out. I didn't see any arcing, so I checked out the spark plug tightness. I had suspected the right-hand side because the symptoms happened after it had been parked as I was at work, and when I checked the tightness, the RHS was indeed a fair bit looser than the LHS. Not loose, mind, just noticeably easier to tighten than the LHS, so I did it up to match.

I think out of paranoia of overtightening it and leaving a sheared plug stuck in the head, I didn't tighten it enough to crush the washer when I first installed it, allowing water to get into the threads and ground the plug. The bike was fine in this evening's rain, although it wasn't half as strong as yesterday and hadn't been going for nearly as long - I guess only time will tell whether this actually was the fix.

I got the idea from Kiwingenuity who had the same thing happen here: http://gstwins.com/gsboard/index.php?topic=72757.0

[Kiwingenuity]

Hence the reason I went and bought a nice small torque wrench for doing up my plugs..