Blown rebuild

[Pittsburgh400ex]

well, had my guy tear down my 400 after a fresh 416 rebuild, turns out the piston was broken in 4 different places, was a sparks racing piston, 12.5:1 made by JE, he said he has never seen one blow apart like that. was wondering if you guys had any ideas what would cause it. gonna knock the compression down to 11:1 and run a weisco 20-30 over 416 i think, depends what is available.

[TRXRacer1]

That's odd, very odd. These don't go in ranges like 20-30 but anyway if you're at 87mm, 88mm is going to be your next option. Is sparks going to do anything for you?

[jcs003]

good to see another rider from the pittsburgh area. welcome to the site.

were you running the correct octane fuel?

was it broke in properly?

crazy things can happen to a piston if its detonating while being ridden hard.

[TRXRacer1]

Originally posted by jcs003

crazy things can happen to a piston if its detonating while being ridden hard. Amen to that. What octane were you running pitts?