Top end shot and maybe bottom too, please help!

[Blown 97 GT]

Ok well i just got my top end rebuilt from the yamaha shop. I left my head up there so the day after i picked up my kit and jug my buddy went to get the head for me and they told him that cylinder was on its last bore, which they DID NOT tell me! Well yesterday while riding for the first time after breaking it in, it fried the piston and melted the rings to it. The top side of the piston has been shaved off and is missing chunks and some of them are still in the part of the jug that connects to the head pipe. So im guessing that since it was on its last bore it ran way too hot and fried it? Also after i got my jug off, there was a burn mark on the bearing right below the rod, and the rod has a little play in it. I'll post some pics but any help as to whether or not i need to rebuild my bottom end also is appreciated!

 

[blasterboy91]

if your missing pieces of the piston then they prolly fell down in the bottom and you'll need to split the case and clean it out...also it sounds like you didnt jet it right so thats why it blew...and if it was on the last bore then you need to buy a new stock head or jus go big and get the 240 kit...

 

[Wildcard2]

The crank will have some side to side play in the big end rod bearing. But if you suspect any piston material in the bottom end you should split the case and clean it out as said. Did you diagnose why it went the last time? Probably the same reason it burned down this time too...air leak? incorrect jetting? Bad fuel? As for your options now, you can look for a low hour top end, have yours sleeved or get a 240 kit. Options are endless and it all depends on how much you want to spend and how much power you want out of it.

 

[custom2stroke]

almost sounds like you ran it low on oil or didn't mix it correctly for it to blow in one day.

 

[blasterfreek30]

and the burn marks on the crank are common, ive seen them on all the cranks ive changed

 

[89custom]

I say you check that sh*t over personally for air leaks, and if the shop fully reasembled it for you(i couldnt tell from ur post) then bring it back to them and say what the I love you didnt reasemble it correctly and it had an air leak that fried the piston.

also could been jetting but im leaning towards airleak, since it was just rebuilt.

 

[jeepinncreepin]

what main were you running?my motor seized twice in a month.had an airleak on the carb nipple where the oil line went wasnt plugged,had filter on carb so i needed to upsize the main,last but not least was mixing sh*tty oil with my gas. fixed all that ran like a champ then it got impounded lol.you were on your last bore but that shouldnt really matter.

 

[DUALSTROKE]

Are you still running oil injection.If so then you need to run a tank of premix in it for the break in period.

 

[Blown 97 GT]

No the oil injection has been removed. Where should i check for air leaks because i do not want this to happen again. What is the best way to tell if an air leak is there or not? Im going to take the top end to yamaha and see what they say, maybe they'll re-sleeve it for free or something idk. And i was running a 310 main jet so i know it wasnt running lean but it wasnt running rich either i dont believe. With my mods listed, what do you guys recommend me running main/pilot jet wise and also where should my needle be? Thanks in advance...

 

[Blown 97 GT]

And I really dont trust myself to split the case to check everything and then put it back together, so who should i get to do this? I can ask around here but i dont know anybody off the top of my head. I'm thinking about just getting my jug re-sleeved back to the standard bore, then send it to flotek for them to port it and lighten my flywheel. Anybody know what yamaha charges to re-sleeve?

 

[Blown 97 GT]

Anybody? I need some advice!

 

[2smoker85]

if you plan on sending it to flotek, just send it to him now, he can reseleeve it and do ur port and polish. or wildcard hes good, he did my head.