Spark Plug Threads !

[thezfactor]

Has anybody come across this problem before ? All four spark plug threads on my Z900 cylinder head are pretty much shot, no problem I hear you shout. I've got a Helicoil kit to correct the problem. Now here's the rub, it turns out that one of the holes has already got an insert in it ! I've taken the loose insert out, and the insert tap is a very pissy fit (engineering term) in the hole, no metal has been cut but a new insert inserted, and the result is the same "unusable". The Helicoil tap cannot be any bigger as it is just about to touch the valve seats now !

[jimmock]

Sounds like a nightmare.

[z1bman]

loctite the helicoil then use a thread chaser to clean the helicoil



http://www.ebay.co.uk/itm/like/19124417 ... ue&ff13=80

[1962royp]

I had this with my B2
Take to an engine builders he will put a steel insert in. back to std

[z1000puddin]

I had one like this in my A1 Thou head
Big sert is a next stage up time sert
http://www.timesert.com/html/bigsert.html

[thezfactor]

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As you can see here the helicoil insert was touching the valve seats.
So I have decided to tap the hole out 3/8 bspt and make a special plug to fit.
The downside is I will have to do all four cylinders.
And I will fit 10mm spark plugs.

Here is one of the four off plugs that have been made, complete with a hex drive to be inserted into the head.

Plug fitted.

Spot faced off to achieve a flat face.

A bit more dressing off still to be done.

There you go job done x 4.

[PAULJAC47]

Nice work John...

[kev edwards]

A man after my own heart, thinking outside of the box and a bloody good solution to a problem that rears it's head too often, that is much better than sending it to scrap, though some will scoff at it, this sort of thinking saved many £'s on my old thou.

[andy c]

John,
Nice job, a man after my own heart.