Modern Vespa

I've attached a picture below of two spark plugs that I've purchased at Halfords about a month apart from each other both of which have broken in the same place I've been trying to think of my reasonable explanation for this but nothing comes to mind the plugs are perfectly colour so mixture is good I have my eyes on temp gauge and it never goes past half way what could be the cause for these spark plugs to break this way?

Is it the correct grade of spark plug? If not, is it too long and the piston is hitting the electrode?

The original plug is a cr8eb and the ones I have are cr8eix which on ngk's upgrade chart are the ones I need

Only thing I can imagine is that the Iridium fine wire 0.6mm center on the CR8EIX is doing this, they both have same specs except this, the CR8EB is Nickel and 2.5mm thick center, see specs in links below.

https://www.ngk.com/ngk-4218-cr8eix-iridium-ix-spark-plug

https://www.ngk.com/ngk-7784-cr8eb-nickel-spark-plug

Credit scooter center for info below

electrode material
Here comes copper, platinum, silver or even iridium.
Copper is the most common, followed by silver and platinum. Due to the high prices for the precious metals, the spark plugs are also correspondingly more expensive than their copper counterparts.
The material is ultimately almost only interesting for wear, only the extremely thin iridium electrodes (Ø=0.6mm) have a higher ignition voltage, the spread of the flame front in the combustion chamber improves.

Can you use the CR8EKB ? That has two arms on it.

Yep good idea that is

https://www.maxiscoot.com/en/product/spark-plug-ngk-cr8ekb-4374-48828

where does that tip end up? bouncing around in the cylinder? could the first one bouncing around have damaged the second? or did you rip the head off to get them out?

defiantly put a camera down the hole and inspect the top of the piston and the cylinder walls.

The product manufacturer has some legal issues.
A good product (spark plug) would never do that under any circumstances.
Maybe it's a bad run at the factory or the materials supplier to the manufacturer had a bad run.

I just bought a handful of NGK plugs for various bikes that have yet to be installed. Do you have a source for the legal issue information?

Maybe someone at Halfords is swapping them out for the counterfeit ones.....

Really bad pre-ignition (detonation) can cause this. But it's more commonly caused by the piston colliding with the electrode. Do you have the original spark plug? If so, compare the length of the threaded section to make sure the new plug isn't extending too deep into the combustion chamber. Also, you might take a look at the top of the piston to make sure there isn't a thick buildup of carbon causing the piston to hit the electrode. You'll need a scope to look for carbon buildup on the piston.

I'd definitely go looking for the broken bits. Best case,they get blown out the exhaust valve. Worst case, they get lodged between the valve and the valve seat leading to a bent valve.

If they went out the exhaust then they'd get stuck at the cat so could remove exhaust and shake to see if you could hear them. If not then ...

Gooqle; NGK Recall

I can't really tell the difference. Maybe they are a knock off.

So don't Google, NGK legal issues?

You can if you want, I did it my way. Recall NGK.

https://www.aussiefrogs.com/forum/index.php?threads/issues-with-ngk-plugs.139324/

Wake up call for myself, I did not know this, damn the scammers

the body above the threaded area, you can see the fake ones are thicker than the real ones as it gets closer to the hex area. also the printing looks slightly larger.

the body above the threaded area, you can see the fake ones are thicker than the real ones as it gets closer to the hex area. also the printing looks slightly larger.
so when comparing to the failed ones from the OP looks like the failed ones might be fake to me

I'd be inclined to identity them as throwaways from the OG manufacturer, that someone got a hold of. The black market for this is in your hand.

If you had a bunch of counterfeit spark plugs, would you try to sell them to Autozone, or would you put them on Ebay? The big retailers that buy directly from the manufacturers aren't selling counterfeit spark plugs, and NGK doesn't let people dumpster dive at the factory and dig the bad ones out of the trash.

Back when we had the scooter store and were constantly sourcing parts for Chinese scooters, I was offered NGK plugs for an insanely cheap price from the same supplier that wanted to know if I wanted Gates belts or belts that just said Gates on them, and were considerably less.
That's when I stopped selling Gates belts and switched to Denso plugs on all my own vehicles and in the shop.
Halfords probably buys directly from NGK's national distributor in the UK, and not some random guy on Aliexpress. It is the right plug for the GT 125. So why did two spark plugs you bought a month apart break in the same spot, and why aren't other people sharing this experience? I have no doubt Halfords sold more than two, and if there's a manufacturing defect, other people would have noticed it.
What work was done recently to the bike? It could be that the cam is off a tooth or so, but then you would likely notice a big drop off in power. Are you re-gapping them yourself, instead of taking them out of the package and installing them as is? If so, what are you using to gap them? Does it come into contact with the electrode near where it's breaking off?
If you are setting the gap, try not doing that next time and see how it works out. They are pre-gapped from NGK.

I thought the knock-offs were only CR9EIX (meant for big inline4 sports bikes, etc. I'm about to buy some for my MV Agusta)

And there are SO many threads on this, the easiest way to tell is by the outer boxes:

https://www.driven2automotive.com/shop/blog_img/uploads/2018/07/boxerrorfakecr9eix.png

and the tip:
https://www.apriliaforum.com/forums/showthread.php?366972

Iridium Plugs are not to be gapped EVER. If the gap isn't within spec than it's the wrong plug, or damaged.
Regardless, if the guy gapped them and it damaged the electrode it hasn't been mentioned as I've read it. From spark at the plug gap (so were perfectly clear) to the coil every bit of the path has a spec. I'm not being a purest in this talk, it's electrical engineering that should never be "souped up"
Older styles are more robust and durable compared to modern technology.
Regardless the primary circuit is what it means.
Every ohm, amp, volt, material, length and density is measured to a very fine point to get the most out of both ends of the equation. Profit and Power

Looking like the next tool in the Xmas gift box is a magnifying glass to see the welded or not Iridium tip.

still waiting for the OP to find where the tips ended up bouncing around - cylinder or head

they go with the flow

One can hope so but checking in the exhaust to confirm is recommended (as above).

Probably lodged in the exhaust or on the ground, or hopefully cracked a Prius windshield.


Or the remote possibility that the plug ate itself there, who knows with all the soup that's made. One Molecule at a time.

Sorry all been busy with life I have purchased the original cr8eb and it's running albeit a bit slower on acceleration but it runs like normal I didn't investigate where the tip ended up but seeing as I've done a few hundred km since then I'm pretty sure it's all okay I will take a look later at the lengths but the cr8eix is meant to be a replacement for the cr8eb

As too if their fake or not I have suspicions one of them is you can clearly tell their not the same one has nice sharp writing where as the one I believe is fake has a bolder darker writing on it

I am running an upgraded ht coil wonder if it could be the cause

The molecules are probably bouncing around back and fro to the piston and back to plug. As long as a bit sooty no worries brah. Although personally I keep mine a rich brown color and scare death away with my occult practices.
Probably why god doesn't let me have a scooter of late.

You really believe you can tell a difference between how the bike ran with an iridium plug and how it runs now? If you can, it's not the spark plug that's making it happen.
What many people don't know is that the standard copper core plug puts out a better spark than an iridium plug. Manufacturers didn't go for iridium because it has a better spark. Manufacturers went with iridium because, even though it's not as good a conductor as copper, it lasts forever. They traded a better spark for 100K mile spark plugs.
Now this upgraded coil might be another matter. If it's one of the orange coils they sell on amazon or ebay, it's likely not really an upgraded coil, but a cheap coil that is orange instead of black. They break down fairly quickly. If you know who made it, and it's a company that is in the business of making high output coils, that's another story.

I'm gonna have to disagree on the claim that you aren't able to notice the difference, the copper option has a bigger center electrode meaning the spark kernel is not as concentrated. Where as with the iridium option it has a fine wire 1.5mm electrode which produces a more concentrated spark kernel.

The coil is a naraku brand not some ALI buy.

What I want to try is run cr9eix or denso iu27 as they are colder plugs.

Also could the heat range have anything to do with this as it appears to me that this could have occurred during long periods of WOT on A roads which is pretty much the whole way to and from work 20+ miles each way

Clearly the bike isn't tuned correctly, in this manner the plug is just taking up slack for the that.
I think owner cut the electrode off to eliminate the shadow, because it's over rich.

Naraku sources quality parts.

You can disagree all you want, but if one plug really made anything perform noticeably better, nobody would buy the one that made their vehicle perform worse. Fuel economy will drop, the engine won't meet emission standards, oil will break down sooner, carbon buildup on the valves, etc. And they would stop making that plug. The sales pitch, "You will notice that your bike doesn't run as well, and the fuel economy will drop for the next ten thousand miles, but you save $3," doesn't sell a lot of anything.

As far as going to a cooler range, Piaggio already did that. The 7 range NGK is in all the Piaggio engines, but they go to a colder plug for the Vespa models. You aren't burning a hole in the top of the piston, and you won't benefit from a colder plug. Your bike has run since new with the correct plug in it. If it's not running fine now, it's not the plug. And if your bike has high miles, it would probably benefit more from a 7 range plug than a 9 range plug. It will start a lot better in the winter.