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Discussion Starter · #1 ·
Hi,
I am trying to repair a badly crossed thread in a CB200 spark plug hole, ( not done by me ) and I have read on an earlier thread that it is possible to do without removing the head by using the Vorlux plug thread repair kit and plenty of grease to catch the swarf. My question is whether the old thread will need to be drilled out or will the tap supplied in the kit cope with removing the old thread whilst it is forming the new larger diameter thread.
The previous thread I read was for a repair on a plug that had blown out so I presume the thread had stripped out too leaving a clean hole. Has anyone used one of these kits and what was the outcome. Any help much appreciated.
Regards,
Glyn.
 

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Get a time-sert, available at auto parts suppliers. The instructions that come with it should answer your questions. I would expect drilling to be required, again, the instructions should explain.
 

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I usually try a heli-coil first, it's cheaper and easier. If things don't work out you can always make the hole bigger and use a time-sert. They make a tap with a smaller diameter end that pilots in the original threads and makes the new threads perfectly straight.
 

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There are people who say the plug threads can be repaired with the head on the engine. It is not that big of a job to remove the engine and pop the head off. The risk of FOD damage is real and you may wind up pulling the head to repair the valves.
 

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There are people who say the plug threads can be repaired with the head on the engine. It is not that big of a job to remove the engine and pop the head off. The risk of FOD damage is real and you may wind up pulling the head to repair the valves.
I'd second that. In fact, once the head is off, might as well do both sides whilst you are at it. That said, I'd take the head off myself, but probably take it to an engine shop to get the inserts fitted.

Shame really, as the plug threads in the CB200 head are much deeper than the ones in the 175 head, presumably they made this change to try to avoid this issue.
 

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Discussion Starter · #6 ·
Hi,
Thanks for all the info and help I think it's definitely engine out and head off to do the job.
Regards,
Glyn.
 

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http://www.hondatwins.net/forums/1-project-logs/41251-1971-cb350.html

Glyn,
There are pics of the kit I used in the link above, page 3. I'm not sure if its the same as what you have available in the UK but it was very easy to do.
The tap stepped up and reamed out hole larger then cut bigger threads all in one process, no drilling.
I don't think I would attempt it with head still on engine but people have and claim success.
If you are capable of pulling engine, removing head and have the time then you might want to consider doing it this way. Then you will be 100% sure there is no material left in cylinder.
Good luck, take pictures of how you did it and post so we can all see.
 

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I'll second the Time-Sert. They are far superior to Heli-Coil. The TS kits are more expensive but are definately worth it.
 
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