Fx1 motor blew up!

Sucks, trying to figure out what happened. 93octane and 50:1 Premix, had been riding great all week long until this!


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Rockin' the SQUARE!!!!
Site Supporter
Granbury, TX
I'll go out on a limb and say you went lean. There's no visible piston wash... Check your carb filter and your fuel filter. You might have also sucked air through a fuel selector or primer. Also check your crank seals. What was your jetting?
very low hrs on the motor, fogging every season. Have always changed the fuel filter but not carb filter actually. Fuel selector was deleted but I do have a primer hooked up. Always give it a few pumps on a cold start and let it warm up. Not sure of jetting will report back
Other piston


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manic mechanic
Twin Lakes AR
Wouldn't the piston tops be a bit cleaner? No trying to argue, but to learn. What's your reasoning?
LOTS of water ingestion/intrusion will steam clean the piston top and dome, and keep all the lube washed off the piston so that it scores and usually locks up. A little bit at a time leaves that sludgy grey substance you see on the piston. All the while causing detonation and eating away at the squish area of the piston as you see on this one. I'd also like to see a bit more wash on that other piston. Not lean enough to damage things but a little fatter sure wouldn't hurt.
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