Cross Threaded Spark Plug Hole

[gaillarry]

My son decided to change the spark plug and cross threaded the hole. He got the plug about 3/4 was in and of course it won't go any further. I got it out but what's the best was to fix it???

[alantf]

If he didn't put too much pressure on the plug spanner (wrench?) & bugger it up completely, you MAY be able to just screw the plug in correctly. Have you tried that yet? :??:

[gaillarry]

Originally Posted by alantf

If he didn't put too much pressure on the plug spanner (wrench?) & bugger it up completely, you MAY be able to just screw the plug in correctly. Have you tried that yet? :??:

Yes I tried that but it keeps going into the threads he screwed up. I was thinking of getting a thread chaser - what size would I need?

[alantf]

Unfortunately, I don't think it's that simple. You may already have bits of thread (metal) in the cylinder, that could bugger the piston rings, & a thread chaser may only add to the problem. You'll probably need to remove the cylinder head to assess damage & carry out a repair.

Is there anyone with more "hands on" knowledge who can come in at this point? :sad:

[Easy Rider]

Originally Posted by alantf

Is there anyone with more "hands on" knowledge who can come in at this point? :sad:

I think you are basically correct but it depends..........
On how old the bike is and how willing you are to take a chance.

If a new plug won't follow the original threads, chances are that the thread chaser won't either.
That might be a good solution IF you could start it at the other end where the threads are good.
Alas, I think on the GZ, you need to take the cam off to remove the head......so it isn't a real easy job.......and if you're going that far, might as well heli-coil it for a proper fix.

IF the bike is OLD and/or you really don't have the skill or the money to do it "right", a thread chaser from the outside....with lots of grease on it to catch the filings....probably wouldn't make matters any worse and you might luck out. Any filings produced will PROBABLY blow out without doing any real damage.....maybe.

Someday maybe I'll tell my "rock through the plug hole story" but not today. Sufice it to say that one needs to be VERY sure that the base of the old plug is absolutely clean before you unscrew it. :roll:

The second big question IS: Does the boy now know to use FINGERS ONLY when threading in a plug ???

[patrick_777]

Originally Posted by Easy Rider

Someday maybe I'll tell my "rock through the plug hole story" but not today.

That is a pretty good story, though.

[blaine]

[quote=patrick_777]

Originally Posted by "Easy Rider":r4gysxrt

Someday maybe I'll tell my "rock through the plug hole story" but not today.

That is a pretty good story, though.[/quote:r4gysxrt]
:plus1: But a hard way to learn a lesson!

[Easy Rider]

[quote=patrick_777]

Originally Posted by "Easy Rider":1fuxym20

Someday maybe I'll tell my "rock through the plug hole story" but not today.

That is a pretty good story, though.[/quote:1fuxym20]

Oops. Have I told you the story about.............
Yes, Gramps, we heard it before !!! :roll:

[emory70]

that was one of the first lessons my dad taught me... "whenever possible, start a bolt, nut, screw... with your fingers." that was followed closely by "don't tighten anything until all fasteners are started."

[GTGZ]

Originally Posted by emory70

that was one of the first lessons my dad taught me... "whenever possible, start a bolt, nut, screw... with your fingers." that was followed closely by "don't tighten anything until all fasteners are started."

Same here! The thread size is 12x1.25mm 98.9% of auto engines use 14x1.25 threads & all thread chasers that I have seen are 14mm/18mm so you will need a long reach tap. You may be able to blow out most of the shavings if the piston is at TDC on the exhaust stroke.