Another Snagged Exhaust Port

[douglee25]

I'm posting this for Goose. He's having trouble posting images for some reason.

He said the motor was warmed up and he was heading over to compete on the weekend when all of a sudden the motor let go.

Any ideas why? Seems pretty similar to my mishap the other week.

 

[#ZERO]

I'd say you need to chamfer your exhaust ports more and double check your piston clearance.

How wide are those exhaust ports?

 

[Goose]

I'm posting this for Goose. He's having trouble posting images for some reason.

He said the motor was warmed up and he was heading over to compete on the weekend when all of a sudden the motor let go.

Any ideas why? Seems pretty similar to my mishap the other week.

thanks for posting the pics.these were pro x pistons i cant believe it was a lean condition cause the plugs looked near perfect.the motor was warm.190 psi cam 2 112 ocatane. i dont think it was catchin a port cause its not over the ex port or anything.the squish was fine that was checked before ran

 

[douglee25]

I'd say you need to chamfer your exhaust ports more and double check your piston clearance.

How wide are those exhaust ports?

I was thinking maybe a reed screw or throttle plate screw since it happened to both cylinders. I'm curious as to why it happened to both at the same time.

Weird?

Doug

 

[#ZERO]

Did any part of the rings break off or are they still intact?

 

[Goose]

piston clearence was .0045 and the ports were def chamferd fine but if you look like i said its not right over the ex port and different spots on both pistons

 

[Goose]

also didnt check for missing reed screws or butterfly screws good call

 

[Goose]

rings intact

 

[#ZERO]

If the edges of the pistons look pitted it could be overheating from detto.

 

[keefer]

Looks like deto for sure. Maybe the timing is way too advanced and a little lean on the main jet.

 

[ROTATION]

Check ring locating pins to see if they were locking the rings properly

 

[Goose]

i think the pitting your seeing on the piston is from the peice of the pistion bangin off the dome and top of the piston.the plugs out of the motor showed no signs of lean.had plenty of octane also

 

[kcr357]

Ya got some weird burn patterns on the pistons; such as that bare spot at three on the right side. Was it ported lately? Det seems likely..

 

[DangerBoy]

it appears the front cylinder had a blown head gasket or o-ring
look for signs of water ingestion on the exhaust side
doesnt look like any detonation, In fact looks rich

 

[Goose]

that may have been from water comming in on the dome washing it up.it still ran that way just not good at all.their was definetly not detonation

 

[Shamu]

post

 

[Matt_E]

That's some good info right there.