CB750 F1 spark plug needs Helicoil

[Priddy]

Hi all, I have had issues from day 1 with no 3 spark plug and it is obvious I need to address this as although the plug is in the thread is not good. I am assuming its an engine out/head off job. Anyone experience of this job/Helicoils?

[Bryanj]

Somebody with experience and skill can helicoil in situ but it is a risk, when in the trade we always gave the customer the option to weigh cost against risk and only ever had one where the engine had to come out afterwards.
As helicoil kits are not cheap it may be worth paying for it to be done

EDIT "proper" helicoil kits are not cheap

[Priddy]

Yes considered in situ but as no 3 (hardest to access) I figured remove the head and get done properly by someone with experience.

[hairygit]

If you're taking the head off to do it, consider spending a bit more and find an engineering firm that uses Wurth "Timeserts" which are far superior to helicoils for strength and heat dissipation

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[Trigger]

Timesert for through hole. helicoil for blind hole 

[SumpMagnet]

For a plug thread...Timeserts are the way to go.

Plugs are in and out far more often than a lot of fixings, and the area is getting a LOT of heating and cooling.

With the head off, you can get a good look at the other plug threads, and make sure all is well there. Done in situ, I would laways worry some swarf will get left behind in there, and damage the bores when you run the engine. Probably not going to happen.....

[Priddy]

Thanks to all, sounds like Timeserts are the obvious choice, always used Wurth kit when in the motor trade so gives me confidence!