Matchstick Posted April 29, 2017 Report Share Posted April 29, 2017 What caused my piston to do this? Detonation? Lean? Or just old. Sent from my iPhone using Tapatalk Quote Link to comment Share on other sites More sharing options...
spurdy Posted April 29, 2017 Report Share Posted April 29, 2017 What caused my piston to do this? Detonation? Lean? Or just old. Sent from my iPhone using Tapatalk Could be detonation but also could have just broke the top edge of the piston off and shrapnel bounced around on the chamber. Sent from my iPhone using Tapatalk Quote Link to comment Share on other sites More sharing options...
spurdy Posted April 29, 2017 Report Share Posted April 29, 2017 It looks like detonation was happening then it broke the piston off and that caused the major damage. Yep, could very well be. Sent from my iPhone using Tapatalk Quote Link to comment Share on other sites More sharing options...
RIPPIN' IT UP Posted April 29, 2017 Report Share Posted April 29, 2017 To melt a hole in the piston I would say lean condition, which in severe cases where the plug & cylinder gets that hot leads to detonation. Sent from my ZTE T84 using Tapatalk Quote Link to comment Share on other sites More sharing options...
J-Madd Posted April 29, 2017 Report Share Posted April 29, 2017 As I always ask in these situations, what does the spark plug look like? Just damaged from impact or is it eroded? Sent from my STV100-1 using Tapatalk Quote Link to comment Share on other sites More sharing options...
Matchstick Posted April 29, 2017 Author Report Share Posted April 29, 2017 It looks like detonation was happening then it broke the piston off and that caused the major damage.. What could detonation in only one cylinder. Sent from my iPhone using Tapatalk Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted April 29, 2017 Report Share Posted April 29, 2017 . What could detonation in only one cylinder. Sent from my iPhone using Tapatalk Air leak. Carb issue. 1 Quote Link to comment Share on other sites More sharing options...
RIPPIN' IT UP Posted April 29, 2017 Report Share Posted April 29, 2017 I am not seeing any hole melted into the piston. And normally this is in the center of the piston. This damage is a piece of the edge cracking off. Is there any damage to the walls? Wonder if some detonation happened, caused the ring to turn and catch a port. Sorry, yeah was looking at the pictures pretty late at night, but most likely a ring got snagged in the port. Sent from my ZTE T84 using Tapatalk Quote Link to comment Share on other sites More sharing options...
spurdy Posted April 29, 2017 Report Share Posted April 29, 2017 Sorry, yeah was looking at the pictures pretty late at night, but most likely a ring got snagged in the port. Sent from my ZTE T84 using Tapatalk But he said it was old. That type of failure would typically happen early in engine life. Sent from my iPhone using Tapatalk Quote Link to comment Share on other sites More sharing options...
RIPPIN' IT UP Posted April 29, 2017 Report Share Posted April 29, 2017 Would have been making some rattly knocking noises before it stopped. Sent from my ZTE T84 using Tapatalk 1 Quote Link to comment Share on other sites More sharing options...
bigweav81 Posted April 30, 2017 Report Share Posted April 30, 2017 (edited) Shit. When I bought mine in 2012 the right side looked just like that. No air leaks, and all stock. Still ran just a bad bog on take off. Wear, and tear literally. I remember the shop had to go from 64mm -65.50mm. Due to the damaged side being so fucking out of round it was unreal, and the scarring on the cylinder wasn't that deep........shit happens i suppose. Sent from my SM-S820L using Tapatalk Edited April 30, 2017 by bigweav81 Quote Link to comment Share on other sites More sharing options...
spurdy Posted April 30, 2017 Report Share Posted April 30, 2017 Would have been making some rattly knocking noises before it stopped. Sent from my ZTE T84 using Tapatalk You'd never have heard anything with that little bit of damage. Sent from my iPhone using Tapatalk Quote Link to comment Share on other sites More sharing options...
RIPPIN' IT UP Posted April 30, 2017 Report Share Posted April 30, 2017 Seen damage before like that in an engine, sounded like a midget with a hammer was inside trying to get out. Sent from my ZTE T84 using Tapatalk Quote Link to comment Share on other sites More sharing options...
JUSTWANNARACE Posted April 30, 2017 Report Share Posted April 30, 2017 What caused my piston to do this? Detonation? Lean? Or just old. Sent from my iPhone using Tapatalk Don't really see any signs of deto. The place it broke out is between the transfer(or right into the first transfer) and the exhaust port so would be kinda of a weird spot to break from a ring snag, unless the locate pin on the intake side came out allowing the ring to spin. 1 Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted April 30, 2017 Report Share Posted April 30, 2017 Don't really see any signs of deto. The place it broke out is between the transfer(or right into the first transfer) and the exhaust port so would be kinda of a weird spot to break from a ring snag, unless the locate pin on the intake side came out allowing the ring to spin.Honestly, after reading a lot about piston development that is a spot that is quite susceptible to gauling or ring land failure if using very round pistons. Believe it or not, the best for some applications are not perfectly round. For instance, when Calvin Pollet developed the Cheetah cylinder they began testing with Weisco and found that the bridge in the triple exhaust was swelling under heat/load and beginning to contact the piston compromising both the piston and nikasil. So Weisco actually did a slight relief on the piston in that area. Sort of similar area where your piston failure is at the edge of the exhaust to the transfer. It's getting lots of heat off the exhaust and then quenched with fresh mixture from the transfer. 1 Quote Link to comment Share on other sites More sharing options...
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