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bad cylinder?

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i recently did a top end using a wiseco piston....the bike was not even through a full break in and only had about 30 min on the new top end that i discovered it had a bad headgasket allowing coolant to leak into the cylinder on the intake side due to excessive piston slap i tore apart the top end and took out the wiseco piston to replace with an OEM piston and i discovered this....any ideas what else could of caused this possibly lack of lubrication due to the coolant washing the cylinder off on the intake side ?

Piston001.jpg

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See those black marks on the piston? You probably have something like it on your cylinder wall too. That usually happens when pieces of your air filter get sucked into the engine. Pieces of o-ring type material will do that too. It scars the cylinder and sometimes you can buff it out, but most of the time the cylinder needs to be replated. Look for flaking in your cylinder the melted material pulls the nikasil right off.

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Why are there holes in the piston?

lubrication i suppose??

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I think wiseco recommend drilling holes in the piston for lubrication.

Don't quote me on that though....

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You use like a number 70 or 80 drill bit not a 3/8 inch drill bit.:p

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You use like a number 70 or 80 drill bit not a 3/8 inch drill bit.:p

i didnt actually drill those holes... the piston came like that straight from wiseco!

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i didnt actually drill those holes... the piston came like that straight from wiseco!

Ok, what bike is this on?

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the little green slip that comes in the Wiseco piston box says that you can drill the holes if it didnt come with it drilled already

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the piston also looks like either it had perhaps too little clearance, or the machine wasn't warmed up sufficiently... if the front of the piston also has wear that looks similar, it would be the classic "four corners" seizure.. a sure sign of inadequate warmup... a more dramatic picture of such a thing may look like this example

DSCF0218.jpg

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no the exhaust side had no marring what so ever and looked spotless

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