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megawatt Speedway Rider
Joined: 03 Apr 2009 Posts: 485 Location: Northiam, near Rye
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Posted: Fri Oct 19, 2012 7:53 pm Post subject: Never seen this before, Sheared sparkplug.!!! |
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Did a service on a mates 2002 ZX636 today. Everything went well until we put the last plug in , NGK CR9E. My mate is new to this, so he was screwing em in until the washer touched the head, tightening until the washer was crushed and then a slight nip up. He did not overtighten the previous 3 plugs. As he nipped it up, the spanner hit the frame??? He gently undid it and I retightened it. It went tighter and then went slack. I undid it all the way and then , oh my god!!
Old plug that came out
New plug.Came out eventually without removing cylinder head.
Neither of us is cack handed and at no time was the plug overtightened. I read somewhere that this has happened to a few people recently. Either NGK have made a bad batch or they are crappy copies, bought frrom a reputable motor factors. BEWARE!!! _________________ Why pay someone else, do it yerself |
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Simon Smith Despatch Rider
Joined: 16 May 2011 Posts: 162 Location: Oxted
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Posted: Fri Oct 19, 2012 10:13 pm Post subject: |
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Not had that particular fault, but we've had several NGKs and Champions at work where the porcelain section has come loose and floats up and down. It seems that there are quality problems whatever the make. |
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Carnage British Superbike Racer
Joined: 05 Oct 2010 Posts: 1432
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Posted: Fri Oct 19, 2012 11:47 pm Post subject: |
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not been unknown to have a duff new plug from NGK ....i.e new plugs fitted and the bike ran like a pig ......eliminated to 1 plug being duff _________________ Rust is lighter than carbon fibre! |
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Loco Monkey With a Machine Gun
Joined: 12 Jan 2005 Posts: 2646 Location: Lost in Space
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Posted: Wed Oct 24, 2012 11:26 am Post subject: |
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Agreed, bad idle problems on the GSXR since I bought it were tracked down to a bad plug having only done 1700 miles ! _________________ The Resident Forum Ghost |
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biggus illitterātus
Joined: 21 Aug 2004 Posts: 31748 Location: Hotel California
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Posted: Wed Oct 24, 2012 12:06 pm Post subject: |
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Loco wrote: | Agreed, bad idle problems on the GSXR since I bought it were tracked down to a bad plug having only done 1700 miles ! |
Mental.
You do get premature failures, but it always suprises me when it's something simple like a spark plug... That said, the construction of a spark plug varies from manufacturer to manufacturer.
You'd think that it's one piece of material from the contact at the top to the electrode at the bottom... Wrong... there are different materials stacked to make the contact from that top part to the electrode, now, given that these are stacked, not welded, or bonded (although sometimes they use springs to maintain contact), it's no wonder that given the different expansion properties of each part could cause internal gaps to appear and cause internal arcing meaning that the resulting spark at the business end is less strong than it could be. _________________
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