Piston is destroyed

Jre720

Jre720

Member
Dec 26, 2016
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so the 98 piston blew up and I knew it was going to happen...it had a bad base gasket so I opened up the top end to do gaskets and the piston was pretty burnt on the top but had no scores in it , the bottom ring was slightly bent and the cylinder had a score so I got it Honed out and told him u might be able to get away with this piston and putting new rings and gaskets but that isn't a good idea...we decided to try it against my better judgment and after about 20 mins of riding it died out , next day rode for 3 mins and he said the top end blew :( I had a strong feeling it would

So my question at the end of that story is do you guys think this is a burn or that the piston broke and is inside my crank
 

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If the piston had been overheated previously it may have have been weak around the ring area.

Fitting new rings and with a fresh hone the sideways pressure of the ring may have been too great for the piston to handle.

The bit of piston is possibly in the exhaust pipe.
 
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I will check that out, luckily it didn't score the cylinder again and I ordered the top end kit already I highly doubt it is in the crank I'll have to look thru the whole exhaust pipe tomorow and check back in
 
just my opinion........
but i have never had a piston break on me
and if that was my piston i would have the cylinder bored/and fitted to a new piston,rings:)
what is the bore on that cylinder? stock measure it somehowo_O
what size piston did you order?
did you ever get a compression test on it after the new rings?
not that compression is the problem here lol
 
speedyslyder said:
just my opinion........
but i have never had a piston break on me
and if that was my piston i would have the cylinder bored/and fitted to a new piston,rings:)
what is the bore on that cylinder? stock measure it somehowo_O
what size piston did you order?
did you ever get a compression test on it after the new rings?
not that compression is the problem here lol
Click to expand...
Never did a test and it is still standard bore and I ordered the standard piston size from wiseco if it was mine I would consider boring but it isn't so I'm gona stick to the basics lol
 
I drained the oil and no metal came out, and I found the whole piece of the piston that broke off in my exhaust so I don't think my crank has any metal in it and as for the cylinder there is no scratches
 
Yes but if metal went down into the crank from the top end wouldn't that be in the gear oil? I'm pretty confident that the crank is still in tact I would at least love to believe it lol
 
No, the crank is separate from the transmission. If it was a 4 stroke metal would be in the oil not a 2 stroke
 
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Good to know ..speaking of transmission..any ways of getting inner clutch basket off without a clutch holder? Need to do crank seal on that side along with clutch
 
Not to be an arse but this has fail written all over it. Did you put a bore gauge down the cylinder to see where you are at? I have a hard time believing that the cylinder is still on stock bore and you keep honing it. I can imagine a bit of piston slap if not worse. You will never find much from that piston in the lower end. You will find fragments in the crank bearings though. Time to actually take some measurements, split the cases to check run out on crank and to check bearings and go from there. Its just a ticking time bomb without using measuring equipment.
 
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I only
Have had it honed out once I used a micrometer and it was still at 66 mm I am debating splitting the case but at the end of the day it isn't my call it's not my bike I am just helping as much as I can
 
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