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Discussion Starter #1 (Edited)
This is my first post in this forum. I've found lots of helpful information here, so as a way of saying "thanks" I thought I'd share some of the more amusing developments of my "project bike" (a 1982 CX500 Custom).

I picked up this bike from a salvage dealer for small money. It had the cyl. head covers off and the main head bolts all removed, but the heads were still stuck on. I say this qualifies as a true "basket case" (some parts came in a basket :) Most of the parts were there, but otherwise it was entirely unclear if I'd get it running or just sell some parts and get out of it. Here's a picture of it on the salvage lot:
It looks like someone was thinking about taking the heads off, but stopped somewhere, maybe deciding they were in "over their heads" or something.
There was a broken-off spark plug in the right-side head, so I'd guess that's why someone might have been trying to remove the heads.

I decided to work on that spark plug first. I thought I could probably get it out without removing the head. The spark plug was broken off between the nut and the threads, leaving nothing to get a wrench on. I drilled it out and tried a #4 spiral screw extractor (no go). After some google searching re. this challenge, I decided to try a square extractor. That too didn't move the plug. Much of the commentary I found suggests that screw extractors tend to expand the soft plug metal, making it tighter in the threaded hole. I decided to get creative. I got a small triangular file and filed four notches in the plug, not quite so deep as to affect the threads in the head. Yes, that inevitably dropped metal filings into the cylinder, but I figured I could clean that out with a pickup magnet and compressed air etc. And if this all fails, I'd be removing that head anyway. The notches I made allowed the square screw extractor could get a good "bite" on the broken off plug. I then fitted a 20in breaker bar on that extractor, and pulled as hard as I dare (not wanting to leave a broken off extractor stuck in the hole). I'll bet I put over 100 ft-lb on that thing, but "no-go" with that either.

Then I thought, OK, let's try some heat. The theory is that: The coefficient of expansion of Aluminum (the head) is higher than that of steel (the plug) so if you heat both up, the aluminum head will expand more than the plug does, reducing the interference between the two. (That's why valve guides are sometimes pressed into the head after heating up the head.) I got out my MAP gas torch and heated up head in the vicinity of the spark plug hole. Again, I could not move the broken plug, but I could at least start to see a line between the plug and the head. I put some penetrating oil on that and left it for a day. After several days of: heat it up, try it, put some more oil on it, ... (repeat) I eventually got the thing to move a tiny bit. (Yea!)
I knew better than to just crank it out. I put more penetrating oil on and left it; screwed it BACK IN a little, just trying to move it back and forth enough so the penetrating oil could get in.
Eventually, the piece came out nicely (where nicely means not trashing the threads in the head on the way out :).
Here's the piece that came out: broken spark plug.jpg

The keys to success were the square extractor and filed notches. With that, I could "ooch" the part both directions to loosen it up, leaving the aluminum threads intact.

Now I realize, the procedure I used would take WAY too long for a professional mechanic to use, but it worked well for me. Now I should explain here: I come from sort of a "motor head" family. My father worked on cars (mostly because he was a penny-pincher:) My brother and I also worked on cars, motorcycles etc. Actually, my brother was a professional (factory trained) motorcycle mechanic for many years. So I have access to excellent advice. Also, since this is a project just for fun, I have time. I can tinker on it, try things, go away and think, come back and try something else...

Anyway, I want to thank everyone who takes the trouble to post with their experience in a forum like this. I got the idea to try a square extractor from one such post.

I'll share more about this fun as it proceeds.

4,278 Posts
Hello Gordon and welcome to this forum :)

Yes, that inevitably dropped metal filings into the cylinder, but I figured I could clean that out with a pickup magnet and compressed air etc.
Magnet for steel metals is okay.
But the ""motor head" family" has developed a magnet for the insulation ceramic around the tip of the plug ?

Some ceramic glitter pieces will stay in the cylinder, very small parts between piston and cylinder wall. I mean the gap between the first compression ring and the top of the piston.

Greetings from here
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