Dumb question (maybe) but Did you do the run in procedure?
Yes, followed IAME manual
Sahib,
I was in Charlies pit when this happened. Just glad youāre okay is the important thing. We talked about the possible causes, but in all my years of experience racing dirt bikes a failure this catastrophic is kind of rare and lends me to believe it could have been a mechanical issue versus simply running lean. Iāve had motors go lean due to a failed crank seal for example and seized the motor. The cylinder wall had galling, but the motor didnāt grenade like that. Your loud ping/bell ring when it blew tells me that something like the piston breaking is more theoretical. It was sudden versus what Iāve seen in extremely lean occurrences. Hope you get your answers and if IAME foots the bill, thatād be great. Keep your chin up and hope to see you back at the track soon.
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Looking at the damage, I suspect that the piston itself fractured, it does not look at all like a lean seizure, which even at 15000 RPM just looks like the piston smeared onto the wall and stopped gently. Even if IAME does not pay for the rebuild I suspect theyād like to have the parts back as they may have a bad batch of pistons and may want to tell everyone not to use them. 4 hours is well past the break-in time.
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Just called IAME,
The gentleman I spoke with was very nice. Stated that I need to ship the engine to them so they can take a look. Going to do that this week.
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I also wanted to thank all of you who have given input/advice. All of your knowledge is greatly appreciated and I feel better knowing that it may well have just been a failure out of my hands. While itās frustrating it happened Iām glad I nor no one else got hurt and in the end parts can be replaced people canāt.
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Best of luck with it, and let us know what IAME have to say!
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I lost a couple Yamahas in the past to defective pistons. Same sort of failure. I think there was a small run of bad pistons for the KA a few years ago too, so not a totally uncommon thing.
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^ This. It would be incredibly rare for a piston to shatter like that just from siezing in the bore. I guess itās possible that you could have a combination of a questionable piston binding to the bore and then being shattered by the force of the rodā¦ But it seems remote to me.
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Most likely this was caused by the piston breaking at the wrist pin bosses letting the rod loose to destroy the rest of the piston along with other things.
Itās happened before, Iāve seen it in Leopards, Yamahas and others.
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I was gonna say it looks like things got hit around repeatedly, not just one big shatter
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When Jim Busby and David Hobbs were driving the BMW 320i Turbos in IMSA (early 80s +/-) Busby came up to the corkscrew at Laguna Seca in practice and KABLAMMO, blew the F out of the motorā¦ like the crank ripped out of the webbing of the block, went through the oil pan and crank, rods, and pistons went tumbling down the trackā¦ in a sea of oil. Good times. 
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OG kablammoā¦love it!
Looks like my engine that overheated, then it blew. Same sort of damage. Piston turned into a bunch of pieces. The arm went through the engine.
Kinda similar
Doesnāt get much better than sending the rod through the cases!
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Iād concur with those whoāve said piston failure. Iāve had a few that failed like that in the 100cc days and my engine tuner would just take a look, tell me it wasnāt my fault, take the engine away (presumably to go in the garbage) and give me another one.
My best Yamaha did that. No rhyme or reason, just shattered the piston and annihilated the head.
RIP Sandy.
when the motor is that good it gets a name!
The motor my kid used last year was so good, i named it Shit.
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So a Rotax, then? Badabing-tiss!
(Please rotax, Iām just kidding)
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