Other Has anyone else had NGK plug failure (ceramic coming loose from base)?

[SuperJETT]

93 octane 40/1 oil msd enhancer. Let me reiterate that this has happened throughout this entire season on same motor w/no new mods, and no signs whatsoever on piston or electrode area of preignition.

If it's continually happening, then that's a sure sign it's your tuning causing it. Just my opinion.

I used to have a mid-high 50's mph SXi that had several plugs crack one summer. The combination of center bleed pipe, WOT runs on glass, advanced timing, and a high pitched impeller caused detonation even though the engine ran great and never seized.

You have a milled stock head, who did it and for what octane gas?

 

[jetpilot36]

i wish i had the porcelein fail on me.in my case the electrode dropped off into my cylinder.scored my new cylinder and head.this was a few years ago. i think it was a br8es or hs (the short one)

 

[Billybo455]

it's a hs if it's the short one and electrodes don't just drop off....

 

[spork]

If I remember correctly we took off 3mm 3 or 4 years ago. Once again I don't feel it's tuning. I've always ran my ski fat and the plug is far from showing it's been lean even considering the loose ceramic leaks compression and would lean it out more. Same electronics, same carb, ski runs great, and shows no signs of anything being wrong. I'm sending at least one plug to ngk tomorrow so they can analyze it and tell me what they think. I'm sure if there's a combustion issue causing this they will let me know.

If it's continually happening, then that's a sure sign it's your tuning causing it. Just my opinion.

I used to have a mid-high 50's mph SXi that had several plugs crack one summer. The combination of center bleed pipe, WOT runs on glass, advanced timing, and a high pitched impeller caused detonation even though the engine ran great and never seized.

You have a milled stock head, who did it and for what octane gas?

 

[steve-uk]

I had 2 fail out of the box this past summer, both from the same case. I installed them the same as any other time. Both cracked when I tightened them down. One shattered completely, the other was found loose when I pushed on the spark plug boot and lifted right off the base.

i had a couple crack on installation too, the ceramic completly shattered off the side

 

[Algonquin]

I would say there is a vibration issue, and I agree that the squish should be checked.

Years ago this continuously happened on a friends 701 and we couldn't figure out what was causing it. The porcelain would come loose from the plug every hour or so of riding. Plug color looked alright, etc.

The motor was eventually torn down since the crank went and we found the engine had no squish gap. We could read .050 on the dome from the piston. The cylinder had been decked at some point and he was just running regular ADA 180 psi domes. Funny thing was the motor ran pretty good when it had a fresh plugs.

 

[spork]

I will check the squish this weekend just for $hts-n-giggles, but again this is the same head I've been running for years without it happening. I'm not saying there isn't a possible problem with my motor or tuning, but just doesn't make sense to me that that's the case.

I would say there is a vibration issue, and I agree that the squish should be checked.

Years ago this continuously happened on a friends 701 and we couldn't figure out what was causing it. The porcelain would come loose from the plug every hour or so of riding. Plug color looked alright, etc.

The motor was eventually torn down since the crank went and we found the engine had no squish gap. We could read .050 on the dome from the piston. The cylinder had been decked at some point and he was just running regular ADA 180 psi domes. Funny thing was the motor ran pretty good when it had a fresh plugs.

 

[kev.t]

i've had this. went through a full box of plugs getting one outing a time before one would fail,(different pot each time) no obvious signs of failure, just stopped sparking. bought another box of plugs from another supplier and the problem went away.

 

[jetpilot36]

it's a hs if it's the short one and electrodes don't just drop off....

it certianly did in my case.broke right rght off and bounced around in my cylinder.so yes...electroes do malfunction and become detached from time to time.im not the first one this has happened to and wont be the last.now i always inspect my ngks closely before installation.

 

[WFO Speedracer]

I have probably replaced more NGK plugs than anyone else here, I have rarely seen any problems with them, every once in a while though you will get a dead plug right out of the box and I have had a few that the insulator came loose on, still better than anything else out there bar none.

 

[spork]

Just an update I got a call back from Jason, and was informed that i was over torqueing the plugs. I'm very skeptical of this, but will give them the benefit of the doubt and see what happens next year. Guess if all else fails there's always "denso".

 

[yankeeboy]

whats correct torquing specs for a spark plug? I always just make it snug.

 

[Matt_E]

17ft lbs.

 

[fast superjet chase]

i had my ski do this my cause was the squish from head to piston was to tight causing a bad harmonic in the motor. It made my plugs do the same thing. so id try checking that also you dont want to be any less than .050 cause the rods stretching at high rpms and piston swell when its warm.

 

[Freakrider]

For those who refuse to torque spark plugs here's another option from NGK site:


"Tighten the spark plug finger tight until the gasket reaches the cylinder head, then tighten about 1/2-2/3 turn more with a spark plug wrench."

 

[spork]

For those who refuse to torque spark plugs here's another option from NGK site:


"Tighten the spark plug finger tight until the gasket reaches the cylinder head, then tighten about 1/2-2/3 turn more with a spark plug wrench."

That's typically what I do...

 

[OCD Solutions]

That's typically what I do...

Me too.

 

[snowxr]

After working at a NGK stocking dealer for many years and then moving to a NGK distributor, I saw no more than 2 insulator failures - until 2008. After the beginning of 2008 I began to see MANY failures where the porcelin came loose from the metal. I'm leaning toward quality control problems, or possibly a change in mfg. process/materials.

 

[OCD Solutions]

After working at a NGK stocking dealer for many years and then moving to a NGK distributor, I saw no more than 2 insulator failures - until 2008. After the beginning of 2008 I began to see MANY failures where the porcelin came loose from the metal. I'm leaning toward quality control problems, or possibly a change in mfg. process/materials.

Considering how many plugs i have gone thru in the last 10 years, I still find it amazing that I have only ever had 2 fail. NGK has always been my plug of choice and still is.

 

[spork]

Until this year I don't believe I have had this ever happen, and am positive I never had it happen before the last two. Which is the only reason i'm skeptical of the over torqueing scenerio. Pretty sure over the years I've over torqued just about everything at some point.