piston failure marks?

[mustangdave]

hi guys, new guy here. here is my piston I pulled out of the blaster I just purchased last week, I ran the numbers on it and it appears to be a vitos wiseco. I was just wondering what may have caused this failure so I know for when I rebuild my top end. im hoping .20 or .30 over will clear the marks up. ill be using a wiseco piston and cometic gaskets. is there any way I may be able to avoid splitting the case by flushing or anything? I didn't see any material when I removed the top end but that's not to say theres nothing in the crank case. any input would be greatly appreciated!

 

[Blaaster]

I hate to dampen your day, but you will need to split the cases and remove all the traces of piston from the case and bearings.

Detonation caused by improper jetting or more than likely an air leak.

2 strokes should be leak tested often they are very prone to destructive air leaks which cause a lean mixture.

Hi again

http://www.blasterforum.com/general-support-17/downloadable-yamaha-blaster-manual-17325/

03+ supplement:
http://www.blasterforum.com/do-yourself-20/03-06-blaster-repair-manual-supplement-1916/

.

 

[mustangdave]

Hi again

http://www.blasterforum.com/general-support-17/downloadable-yamaha-blaster-manual-17325/

03+ supplement:
http://www.blasterforum.com/do-yourself-20/03-06-blaster-repair-manual-supplement-1916/

.

sorry just saw your reply on the other thread, sorry!

 

[Blaaster]

Apology accepted.

 

[dirtysquared]

Id split the cases, , change, bearings and seals, and send that top end to a good shop to get it matched to a piston. That way your starting fresh and you know you have a good reliable engine.
What Carb is on this Blaster? Check the jets in it also. As Blaaster said, Looks like an air leak or improper Jetting fried your piston.
Here is Ken O'conners video series on Your Engine.http://www.blasterforum.com/engine-13/kor-engine-assembly-vids-no-crank-puller-needed-51169/

Those Video's have bailed me out a few times.

Nice Profile Pic. I'm a bigger fan of the "reeds" on the left side of the pic

 

[thefknboss]

Once metal gets thru the ball bearings it wears them and they get play. Id pull it apart and do bearings seals and piston with an overbore. I have a good jug forsale do it once do it right