stripped threads in spark plug

[azmedic]

Ok.  New here but a quick learner. 
I have a 1995 tiger.  Love the bike.  Hard worker. 
Recently had a loss of power.  Traced it down to stripped threads of the center spark plug in the head. 
Bought a time-sert and replaced the threads.  Seemed to hold well.  Until start up and adding some throttle.
Stripped again.  :(  Or at least it's popping the plug up and loss of compression for that cylinder.
Now what?  Other than buying a new head and redoing valves, etc is there a fix? 
I am not a mechanic, but I know what the issue is and now I'm almost lost.
Looking for suggestions.    Thankful for any help. 
I searched here, but did not see this specific type issue. 

[Sin_Tiger]

Sorry to read that. I have no experience of "Timesert" specifically but have used "Helicoil" many times and never had a failure after repair.

Please don't take this personally as I don't know the whole story but I suspect the repair has not been carried out correctly.

I'm guessing that you did the repair with the head in situ and that will have affected the job. It's not possible to say if it's recoverable until you take the head off and get a specialist engineer to assess the damage.

With the costs of labour if you're going to use a workshop, I would think a replacement had will be your best solution, just have patience to ensure you don't buy a pig in a poke.

[Bixxer Bob]

http://www.youtube.com/watch?v=anjDQJtWFc8 (http://www.youtube.com/watch?v=anjDQJtWFc8)


Looks like you can have a second go with Timesert.  Like Sin,  I use helicoil and never had a problem, but - at a guess - you didn't lock the insert in properly.  If it's beyond repair with Timesert, Helicoil MIGHT work, it's work a go. 

How did you ensure that no swarf from the tapping process got into the cylinder???

[azmedic]

Gents,
  Thanks for your quick replies. 

  I took the head all the way off in order to do the repair.  I have the service manual and followed all the steps in order.  (I even checked the valve spacing and replaced the cam chain while I had it apart) :)  It starts and runs like a champ, until the plug popped again.

  After insertion of the time sert I placed the plug, tugged from top and bottom, checked for any play, removed the plug, checked the time sert again.  I was Very certain that this was a solid fix. 

  Knowing that the head is magnesium, I am dreading a repair and have been looking for a new (used) head. 

I'm still letting the repair roll around in my head some, and I will pull the fairing and tank again today to see how bad it is. 

  Again, thanks for the replies and any thoughts on fixes. 

[Bixxer Bob]

If you've had the head off, did you seal the liners when you put it back together?  Mustang will be along to explain....

[nickjtc]

Knowing that the head is magnesium, I am dreading a repair and have been looking for a new (used) head.

I did not know that! Good to know.