Spark plug insulator around electrode broke off in the motor
 

Twice now in a short amount of time I have had the porcelain insulator break off and wreck my top end. Both times were with an NGK iridium plug. Any idea what is causing this? Or has anyone heard of this happening to them? Both instances were with different heads. First the s3 with the high high compression head and second time with an RK tek head. Squish is right around 1.2 on both.

https://youtu.be/_I4NOqaBD_g

if you've had it before, why didn't you check this time instead of keep riding (back home)? maybe you could have changed spark plug and if you have some tools, quick take the exhaust off and take the bits out?

Possibly a shitty spark plug socket.

I can imagine that a socket brakes the insulator above the hexagon, but his porcelain was broken around the electrode.

My personal opinion is, that the engine suffers from detonation. He has several riding videos on YT and I always have the impression that something sounds weird. Detonation can kill spark plugs...
The engine sounds strange in this video too. Long before the plug failed....

Yes I was just riding it back to my truck. I carry tools with me but nothing to take the springs off my expansion chamber

i thought the same... first i was thinking big end or cranck bearings ...

I am not sure why I am getting detonation. The RK tek head should not be raising the compression ratio that much. I am already running 101 octane fuel. The jetting did seem to have a little lean spot around 1/3 throttle. I will do a pressure test once it is rebuilt to search for a potential air leak.

The jetting I was running at the time was

48 pilot

A/S 1.0

NECH needle on the 5th position ( I bought two needles that are richer on the suzuki chart in hopes I can richen the mixture but keep the same power delivery, I really liked the smoothness of the NECH)

170 main, the main doesnt seem to be an issue since when I go wide open it is fine, the issue seems to be 1/3 to 3/4 throttle at high rpm where I get the lean spot.

Engine mods are
RK Tek head 13.5 to 1 is the supposed ratio per the stamp on the head insert / S3 racing cylinder / House of horsepower exhaust

timing is not adjustable so I don't know how that could be a factor

When I rebuild I am going to back to the GP head that came on the bike when I bought it.

Yeah, the engine doesn't sound right in that video. Sounds lean to me. I would definitely be checking for air leaks. Make sure the exhaust pipe is sealed up well to the cylinder as air can be introduced there as well.

I have seen them fracture the porcelain all the way through. To be honest I didn?t even watch the video yet, just a quick comment before I went to sleep! 😆

Bit of a mystery?
48 pilot- Rich
A/S 1.0-Rich
NECH needle on the 5th position- Rich
170 main-ok
Sounds real lean.It should have eaten that hill climb with ease.
Agree with ss109,air leak or really low float level?
Sorry no help really.