Corroded Spark Plug Base

Can anyone tell me all the sources of water infiltration in the spark plug area? I learned a bit late about protecting my spark plug from water while washing the bike. so, while the plug itself looks good after over a year's wear, the white base was all corroded. I HAVE plugged the little hole on the right side but didn't do so until i had the bike a couple mos. i'm not an engineer, but i'm not impressed w/the spark plug access or the bottomless "pit" Yamaha's built for plug! Other than plugging the hole on the right side & running the bike after a good wash, any other thoughts? many thx, forum regulars....bobwombat

Originally posted by bobwombat:

Can anyone tell me all the sources of water infiltration in the spark plug area?

You, or a water crossing.

When you washed your bike water got into the cavity. Since you plugged the hole it could not drain and sat there and corroded your plug. Leave the hole open. Think of all the bikes out there with totally exposed spark plugs, water isn’t a death sentence, but soaking in it can be bad.

Every overhead cam (or hemi) engine I’ve seen has a cavity in the head cover to house the spark plug, I don’t think there is any practical way around that.

I haven't plugged the hole, so it can drain, but I do run a bit of grease around the spark plug cap, where it seals arounf the top of the motor. I've had the same corrosion problem, until I tried this.


When done washing I spray a shot of WD40 into the hole so as to flush out debris and water. Keeps the plug from rusting also. My .02

So, would it stand to reason to plug the hole when washing but un-plug afterward in order to drain/dry out? thx, bobwombat

I picked up a small right angle rubber vacuum fitting at a local auto parts store. Glued it into the vent hole with gasket sealer, with the nipple facing down. It totally keeps out the water when washing the bike. I've never had any corrosion with this setup, but I do get a little dust from the spark plug hole when I blow it out with compressed air. The rubber boot on the spark plug wire seems to make a good enough seal to keep the water out when washing the bike...

thx, Steve. that's a great idea & i need to follow-up. now, for cleaning out my corroded spark plug hole! bobwombat

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