A New Spark Plug Thread for Camhead

The problem wasn't the spark plug model #, the plug was probably damaged.

Well two blown CR8EIX plugs & coils destroyed in 3 months, both on the lower plug on either side looking like the exact same problem. When I check the NGK website the only plug recommended for the 2009-2012 Camhead is the MAR8B-JDS this is not an iridium plug. There is no NGK iridium plug recommended for the camhead. The NGK CR8EIX iridium plug is recommended for models prior to 2009. It has a slightly different length. I am going back to OEM, I can't afford this experiment. Plug + coil + labor = $250+ each time. Plus been stranded once in San Diego 130 miles from home and the 2nd in Yuma 289 miles from home.

I'm finding this so hard to believe, but if so it's the person installing the plugs and not the plugs.

Installed by BMW mechanic, wish I could blame him and have him pay. Both incidents occurred about 2 hours into a long distance trip with the bike been ridden reasonably hard. The top two same NGK plugs, less stressed plugs installed same time are OK.

At least 3 ADV inmates were witnesses to both instances. Noshoes & I were riding together on the first instance to the TJ toy run. Olebikers pickup was used on the second instance with Noshoes driving the pickup and OBX was there too.

I don't doubt your incident, but according to the specs off of NGKs website the thread size, thread pitch, seat type, resistor value, reach, heat range are all identical. The only difference is the terminal type (one solid and other is stud) and plug hex size. This leads me to believe that the cause of your plug failure was either a defective or damaged plug.

I'm going to put a set in my '12 camhead in about 5K miles. I'll keep you posted.

And maybe for good reason .... just sayin.

Well yeah...they obviously blow up. (I would like to see photos).

So long as the specs (heat range, threads, reach and etc) on the plug are the same as stock there is no risk of incompatibility or damage just because the center electrode is made from Iridium and not Nickle.
The MAR8B-JDS (stock) have the identical specs to the CR8EIX.
Not to mention many people are using the Iridium tipped plugs in their GS's without issue.

The first photos are the 2nd incident, the 2nd photos are the 1st incident??????

OK that sheds some light on this.
99% probability that who ever installed these applied side force while torquing them down and cracked the insulator at the point where it mates to the steel housing, hot gasses passed through the cracked porcelain until the plug catastrophically failed.
This is probably the most common mistake made when installing spark plugs but normally the plug doesn't fire properly and the problem is quickly found, in the gas of the twin spark GS this problem can go undetected until this happens.

I guess I've lived a sheltered life but I have never heard of a spark plug imploding like that. And maybe I've just been very careful when changing plugs on my cars and bikes.

Based on what Jetspeed surmise's I have contacted NGK Tech department and asked them to review. If I get the same "mechanic fault" answer then I will produce the evidence to my mechanic and see what he says. I did have one person tell me when replacing these small plugs you should always use a plug wrench with the rubber inside, since this center's the plug on inserting.
I don't have much faith in collecting anything back, since there is so much deniability. i.e. "You could have dropped both plugs," etc. But at least it will make him aware. (He is anti anything that is not OEM). Thank you for your expertise Jetspeed.
What I have posted is not too say good plug or bad plug, only my experience over the last 3 months. If replacing these with OEM can save me from been stranded on the 8 freeway at elevation in the middle of nowhere, freezing my butt of for 7 hours then OEM it is. I still have 4 NIB NGK CR8EIX plugs that I will put in a shrine.

I'm with the installed wrong crowd. I've never seen a spark plug destroyed like your pictures. When you think about it what we are seeing is not possible unless the plug is damaged. With a spark plug the energy goes in one end and out the other. That looks a lot like combustion gases etc have come up through the center of the spark plug.

the fact that NGK list a platinum AND an iridium option for the hexhead

but NO iridium option for the camhead

tends to suggest NGK don't think any of their iridium plugs are suitable for the camhead

It is possible that both plugs were from the same manufacturing lot and this is a manufacturing defect. Or, as others have suggested, the plugs were damaged at some point. Iridium is just used on the tip of the plug to prolong life, it has no bearing on the other characteristics of the plug.

I also question your statement about the main plugs not as stressed as much as the secondary plugs. I would think that they are under the same amount of stress, both electrical and mechanical.

If you go back to to June 2015 on this thread there were several inmates using this NGK plug and saying they having great sucess, that is where I got the idea of trying them.

Having the top two remain good, & the bottom two on both sides blow seems more then coincidence but anything is possible and it could be a mfn defect. All four plugs were put in at the same time.
I was under the impression that the lower plugs got hotter so worked a little harder ( according to my mechanic.) on a 6000 mile service he moves the top plugs to the bottom cylinders and replaces the top plugs.

But I will be pulling all the plugs and replacing them. If I remember I will post photos of the uppers as well. ​

Installed a set of iridium plugs a few weeks ago. I've only got about 1200 miles on them, but so far they are running well.

Fitted the CR8EIX on my camhead, at around 9000 miles last year due to the bike running rough when I bought it. Turns out the exhaust flapper valve was seized.

The last few weeks, the bike now with 23,700 miles, began running rough. Thought it may need a throttle synch and checked the exhaust valve but other than some minor tweaking on the synch all seemed good. Bike ran smooth again for a couple of days before becoming rough again. Checked the synch with manometers and it was off again. WTF.

Last night did its 24000 mile service and lo and behold the CR8's were done. The lower ones were lightly fouled and the upper ones had a nice tan colour to them, but the electrodes on both had become minuscule, on one side it became the size of a sewing pin.
A couple of deductions, the CR8's gave 14,500 miles of service, but the bigger lesson I learnt was that the ECU was compensating, or attempting to, for worn plugs.

That's interesting. One of the reasons I went to the iridium plugs was that the stock plugs were gone by 12K miles and the bike noticeably ran rough starting at about 9K miles.