Cross threaded tip of cylinder Kawasaki KZ400 1974

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09 Nov 2016 14:01 #747653 by kyan44
So I have accidentally cross threaded the tip of my cylinder of my Kawasaki KZ400 1974. How can I fix this problem?

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09 Nov 2016 15:32 #747664 by kyan44
I do not have a picture, but the tip of the cylinder has been cross threaded. Will I have to rethread the whole cylinder?

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09 Nov 2016 16:53 - 09 Nov 2016 16:55 #747671 by Nessism
What is the "tip of the cylinder?"

Photo below shows a KZ400 cylinder. Which part is the "tip" and what was cross threaded?

Last edit: 09 Nov 2016 16:55 by Nessism.

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09 Nov 2016 16:56 #747672 by Barry2
I'm hangin' on every word too

1976 KZ900

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09 Nov 2016 18:01 #747674 by kyan44
www.motorcycleclassics.com/~/media/Image...589806CBB44F52D98E33

Sorry I am a noob at this. But I have stripped 1/4 of the beginning threads of my spark plug cylinder. Would I need to re-tap it or is there a better way to fix it?

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09 Nov 2016 18:03 #747675 by SWest
You can probably chase the threads with a thread chaser form the AP store.
Steve
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09 Nov 2016 18:15 #747676 by Nessism

kyan44 wrote: www.motorcycleclassics.com/~/media/Image...589806CBB44F52D98E33

Sorry I am a noob at this. But I have stripped 1/4 of the beginning threads of my spark plug cylinder. Would I need to re-tap it or is there a better way to fix it?


A special "thread chasing" tool should be tried first. Failing that, use a solid insert to repair the threads. An automotive machine shop will know what to do.
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09 Nov 2016 18:23 - 09 Nov 2016 18:24 #747678 by JR
Dont worry.
Easy to do and usually easy to fix.
A thread chaser tool like swest and Nessism said.
I made my own once by cutting longitudinal slots in an old spark plug but easier to get the tool. Go slow in and out and use grease to catch shavings. When done use compressed air to blow out any shavings or use a vacuum.
Probably stuff onYouTube . Search Spark Plug Hole Repair

1980 kz750E1, Delkevic exhaust
Last edit: 09 Nov 2016 18:24 by JR.

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09 Nov 2016 18:25 - 09 Nov 2016 18:28 #747680 by Patton
Use a reverse tap that starts at the deep end where the threads are still good and which will cut anew as it proceeds cutting upward right on through the higher damaged threads.



Attempting with an ordinary tap to start the rethread at the top where the threads are crossed is a dicey proposition and risks damaging the threads even worse than they already are. Could easily result in a totally screwed-up un-repairable spark plug hole and needing a replacement engine head.

Good Fortune! :)

1973 Z1
KZ900 LTD
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Last edit: 09 Nov 2016 18:28 by Patton.
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09 Nov 2016 18:28 #747681 by JR
Patton wrote

Use a reverse tap that starts at the deep end where the threads are still good and which will cut anew through the higher damaged threads.


I had forgotten about reverse taps. Much better option than thread chasing

1980 kz750E1, Delkevic exhaust
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10 Nov 2016 13:34 #747715 by kyan44
www.amazon.com/Powerbuilt-640811-Back-Ta...Repair/dp/B0014FGVVW

I used this tool. And it was magical! Fixed my problem. Thanks guys!

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