I dunno, if you plaster the tap with grease and go slow and take it in and out alot it prob be ok!!!!!!! But like i said it depends how desperate your are to fix it.

I have never done it...but...

If you are going to go as far as taking the head of to fix or replace, I would just take the head to a local engineering works. they will either do the helicoil for you or posibly even build the hole back up with a bit of weld then drill / tap back to the OEM size. IMHO it is worth a few extra quid to make sure it is done right first time.

Its not going to cheap if you need to get the head off as you will have to replace the gasket.

Theres a few options once the head is off though depending on budget.

Helicoil / Timersert type drill screw in insert will be fine if done properly, providing you can get the right size / pitch.

You can use something like lumiweld with an oxy acetelyne torch and fill the hole, drill it and re-tap to the oem size. (lumiweld can be brought online if your local engineering place doesnt have it) but you will need oxy acetelyene to use it proeprly.

A local engineering shop can do both of the above if you dont have the equipement or expereicne to do it.

Please be warned that if any of the heli-coil is exposed it can lead to pre-ignition and a hole in the piston. I have seen it happen. Not much of a problem on the old Austin A40. On a motorcycle with a high compression engine it is a different story. Do not attempt to tap the hole out to fit the next size spark plug. In the first instance there is all the swarf that you will dump into the cylinder and secondly there will not be enough clearance between the valve seats to accommodate such an operation.

thanks for the reply guys, the bike is a cheap track bike i picked up for $2000 AUD (1,300 pounds). I prefer to spend as little as possible.. as it will only be ridden once every couple of months...

20 quid
http://www.gfracinguk.com/cylinder-head ... p-783.html

I think I'd ask Graeme what he means by 'good for spares' if intending to use the head rather than strip it...?

http://www.ebay.com/itm/MS002-SEALEY-RE ... 53eebb34df

Might be worth a gamble Just might grab enough thread to give you another coupla years

I was going to get one..so let me know how you get on if you do it.

barryfzr wrote:http://www.ebay.com/itm/MS002-SEALEY-RE ... 53eebb34df

Might be worth a gamble Just might grab enough thread to give you another coupla years

I was going to get one..so let me know how you get on if you do it.

Unfortunately i don't think these are available for 'our' plugs; M8X1.0

It's possible with the engine in 1 piece, there's no drilling with a plug repair kit from timesert/helicoil, you'll get a tap with 2 cutting stages on it. Use plenty of grease on the tap and set the cylinder ready on the exhaust stroke. A blast of compressed air after wouldn't hurt either.

If you can get a 8mm kit for the nc30 is another question and of course there is always a risk doing it with the head in situ.