Corrosion in plug hole

6 replies to this topic
  • Dougie

Posted November 29, 2001 - 08:46 AM


I have quite a bit of corrosion in my spark plug hole. It also is corroding the plug where the plug wrench meets the plug when it is inserted. I don't think it is inside the thread hole.

Do I have to pull the top end to get that cleaned up? It seems to be running fine. Weird though, I noticed it after I cut the gray wire. It was not corroded before this mod.


Posted November 29, 2001 - 08:54 AM


It's really not a big deal as the corrosion you are seeing is not from the head but from the plug and previous plugs you have changed out. The corrosion starts because of water being trapped inside after washing and not running the bike for a few minutes afterwards to allow vaporization. There is a drain on the Right side of the head that is easily clogged by dirt or rust particles. you can easily clear the drain with a can of compressed air directed at the hole. You can also blow the plug cavity out the same way (Leave the plug in the head).

Once I started running mine after a wash job , I never again have had a corrosion issue.

Good Luck...

Bonzai :)

[ November 29, 2001: Message edited by: YAMAKAZE ]

  • Ron_in_SoCal

Posted November 29, 2001 - 09:05 AM


Galvanic corrosion is caused by dissimilar metals being in contact with one another. This is a common problem in engines with aluminum heads. I seriously doubt it has anything to do with the gray wire.

Replace the plug with a new one and put some Never-Seize (?) on the threads before installation. This stuff will stop the corrosion and lube the threads. I will try to find some information while here at work. I've got a can of it at home...

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  • Ron_in_SoCal

Posted November 29, 2001 - 10:43 PM


Read this article from a technical usenet. The last sentence says it all.

Permatex Anti-Seize

  • Bill

Posted November 29, 2001 - 11:55 AM


Blow air into the drain hole prior to pulling the plug wire. It will push the plug wire off (Hick or Boits??? suggestion) and blow all the schmegma :) out of the hole.


  • Shawbridge Husky

Posted November 29, 2001 - 12:19 PM


All good advise. I also like to spray WD40 into the hole after a wash job to rid the cavity of water. It will flush out any dirt and there is no way the plug will ever rust. As for the threads the above advise is very correct, using hi-heat anti-seize is the way to go. As a matter of fact I use it almost everywhere on my motor. ( places such as the header pipe fittings )

  • gavin500

Posted November 29, 2001 - 04:57 PM


if yamaha put the stand on the righthand side instead of the left, this problem would be solved. :)

I use to tape the hole every wash but after changing the spark plug at 5000kms I still had rust and muck, thus don't bother anymore.

Many people say to start the bike up after a wash but I always don't due to using high pressure hose and my air filter always get's quite wet. I should cover it, but it means taking the seat off.

With my new bike I just spray it with WD40 while the bike is lent over and the water comes out. Also after time, another area to watch out is the throttle grip getting corrosion from many washes between it and the handle bar.

But this is all like oiling your chain. I know a bloke who doesn't oil his chain at all and it seems to last near as long as my chain that I use to oil. So now instead of spending money on chain oil I just spray the chain with WD40 after each wash and it's been fine. No more excess oil going on your nicely washed back wheel/rim after each ride!


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