bye bye 780 motor

[w-nut]

i dont think its good when the ring snags the exhaust port in the back cylinder , things kinda go to poooes from there :banghead: . that was max over size so 820cc here i come :banghead:

 

[DR3]

damn:bigeyes: , sorry to hear that man...... good luck with the build, 820 sounds good to me:sneaky: :sneaky:

 

[#ZERO]

Ouch that hurts.

Did you notice the top edge of your Wiseco Pistons on the exhaust side? It’s burnt away slightly from a lean condition. If the piston edge burns away and the top ring is exposed the ring will over heat, causing it to lose its spring tension against the cylinder wall. The engines compression will start to drop after time or worse it could get snagged on the exhaust port like this.
.

 

[willycrumb]

errrr...I guess I have stupid questions.

It seems the ring is still intact? How could it cause that damage if it is still there in its origianal form? To me it looks like something chipped off the piston but then the rings would be shot in that case too. Im confused. Sorry for the Dumb questions....any explanations.

 

[Water Worx]

Looks like detonation to me,the whole outer edge of the piston is sand blasted,deto ate the exhaust side of the piston off & then the piston started coming apart,its not the rings fault.:frown:

 

[willycrumb]

Thanks WW. I thought I was Imagining things.

Shoot doggy... I would reuse those rings on a redneck topend job on a friends boat.

 

[w-nut]

yes there was some deto happening to much timeing , im running 650 elecs on the 750 and the stator plate was a wee bit to advanced and it also had 200+ psi compresion so im knocking back the timeing and lowering the compresion down to the 170-180psi mark so hopfully that will help .
willy there is about 1.1/2 inch bit off ring broken when is got stuck in the ex port .