Iridium failure? (top end carnage) top end time...

[m in sc]

i probably bought them 3-4 ? years ago.  beats me. I'll just go regular from here out.

[KANDY]

I just bought a pair.  

i probably bought them 3-4 ? years ago.  beats me. I'll just go regular from here out.

[m in sc]

I have like 8 i pitched. not worth the possible aggravation. 

[rodneya]

Interesting vid on fake sparkplugs causing misfires. They seem to be pretty difficult to tell apart from the real thing.
Most info I can find online about Iridium issues and misfires are fairly recent and could well be from fake plugs.

https://www.youtube.com/watch?v=7fyD1BXnhtY

[m in sc]

i've heard about that but these were bought at a shop that gets them direct from rocky mtn . If i had ebayed them or amazoned, sure, but nope. these were legit. I never mail order plugs for that very reason.

[m in sc]

So i finally pulled the topend off last night and no surprise... pistons are cooked.

there was no signs the rotor slipped, but this is def igntion related.  melted the exhaust edge off the piston, which leads to late timing.

so, heres the damage. it happend quick too.








and the head. looks fine. got lucky.




the gasket is still on there and i have to clean up the piston slag.

the bores actually look good as well. so, im still leaning towards it having a misfire previosulsy, but not misfiring with the new plugs which exposed an obvious timing fault up high.  as i said up top... NOTHING changed in the ign tune for th epast few years and i jetted UP prior to this run. so.. Not sure. either way, rebuild time.
Im not even mad. just glad it wasnt worse.

[Kawtriplefreak]

Glad it isn't any worse. I know you will figure out the cause.

[m in sc]

still think it was the plugs (old iridiums) misfiring up top. I added spark and bam. im glad as well. but so it goes. 

[sav0r]

Ouch. This is where a knock sensor would be super valuable. Unfortunately it's a hard ask.

[m in sc]

it went so quick it was ridiculous.   

[sav0r]

I believe it. Things were hot in there.

[Hawaii-Mike]

Sorry about the overheating.  Hope you get it cleaned up and back on the road in the near future.

[m in sc]

appears to be NO damage or even aluminum on the bores so should be good

[Striker1423]

Burnt up and exited stage left in the exhaust. Glad the bores are ok!

[teazer]

Left side looks much hotter than right side.  Looks like it's run lean but when it's detonating, the temperature rise tends to mask everything else.

The left appears to have eroded the front (exhaust side) and blown the particles down the pipe.  I prefer fine wire plugs on high performance motors and have never experienced that sort of meltdown with iridum or standard plugs caused by the plugs even with plugs of too low heat range - say B7s or 8s.

Working back a step or two:  If the old iridium plugs misfired, the exhaust temperature would probably be higher.  If standard plugs improved the burn, the motor should have made more power and exhaust temps should have been lower because the burn would have been more complete.

What else changed? Was it perhaps a different fill of gas that wasn't as good as prior fills?  Could the ignition timing have changed electronically for some reason?  The answer should be No F'n way, but stuff does happen. Did it happen at high revs/load and were riding conditions any different.  I'm sure you already asked yourself those questions and more, but that left piston missing the whole exhaust side ring land suggests that the problem was exhaust temperature prior to detonation.  Was air density very high that day?