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sheared spark plug

Posted: Jan 26th, '10, 13:38
by tony-klr
who would have thought that they could be so damn siezed in there LOL

just bought a banging bargain of a bike, W plate 2000 ZR-7 18k miles, loads of new recent bits, but had a sheared plug in it.

knew it was unlikely to get it out, but had a go just in case :)

in the end went up to a 6' bar on the stud extractor and not a thing LOL

why cant everyone put coppaslip on threads like what I do.

currently got the head off and having it drilled and helicoiled, pain in the butt as I have to buy gaskets, but such is life.

thing I cant understand is that the plug doesnt look particularly corroded. guess the fark up pixies just decided it would be funny.

how common are sheared plugs out in biker land

Re: sheared spark plug

Posted: Jan 26th, '10, 16:52
by Funky
I wouldn't have thought they would be that common as you shouldn't do a spark plug up too tight...

Re: sheared spark plug

Posted: Jan 26th, '10, 17:16
by tony-klr
apparantly this one sheared when he was trying to remove it to fit a new set of plugs

guess that the alloy/steel combination not helping

Re: sheared spark plug

Posted: Jan 26th, '10, 19:01
by SteveR3
Have you tried heating up the ally head beforehand, might expand just enough before the heat gets to the steel plug and gives you a chance to bang it out :idea:

Re: sheared spark plug

Posted: Jan 26th, '10, 19:22
by jam
I've just had one done for someone, they'd sheared it off and then tried to get an easyout into it and buggered it all up, so had it spark eroded, and then milled to remove damaged area where washer seats, and a Timesert fitted rather than Helicoil. I won't use Helicoils, Timeserts are far better to use, granted they are a bit more expensive but they are a far better product.
Often plugs will shear when the threads have been damaged or used plugs have been wound in tight and exposed a small part of the thread into the combustion chamber which gets a carbon build up on the exposed threads and then when removed it damages the threads, and that is when the problems start.

Re: sheared spark plug

Posted: Jan 26th, '10, 21:12
by TLS-Moose
To be honest Jam, most decent engineering shops have the same opinion, and many people who get something "helicoiled" actually have them "Timeserted" without realising it :roll:

Helicoiling has become a generic term for mechanical thread repair .......

Re: sheared spark plug

Posted: Jan 27th, '10, 09:07
by jam
I've had helicoils pull over the years, so I invested in a timesert kit with a few commonly used ones. I much prefer them easier to use and far stronger. I've still got some helicoils but rarely use them nowadays.

Re: sheared spark plug

Posted: Jan 27th, '10, 12:25
by tony-klr
yes your totally correct, its the old thing of an item becoming a household name

that type of repair just commonly called helicoil, bit like doing the hoovering, as opposed to the vacuuming :)

Re: sheared spark plug

Posted: Jan 27th, '10, 19:35
by age
Just ask the garage if they are using a Wurth Timesert !!!!!!!!!!

Loads better than A helicoil ! Wish I had them when I was in the trade !!!!!!!!

OH Yes I do work for Wurth :lol:

Re: sheared spark plug

Posted: Jan 28th, '10, 19:47
by deej
i think that people still use helicoils as not many people outside the trade know about timeserts,if you ask for a helicoil then thats what the garage should be fitting. not had to use a helicoil myself but the timeserts are bloody impressive and i dont work for wurth (anymore,oh how i miss all that hassle :P )

Re: sheared spark plug

Posted: Jan 28th, '10, 21:42
by tony-klr
I still use them at home, but didnt have anything to suit the plug size and with the plug at 45 degrees I didnt want to risk ballsing it up

got a call today, they got the plug out clean without touching the threads, think they wound it out the bottom of the head, sounds suspiciously like someone suggested, the plug had been reused, tightened down and carbon built up around the bottom

oh well £12 is enough to be spending on it anyway LOL

damn gaskets cost me £75 :(

hmm bargain bikes