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Cr85 piston damage

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I just put a brand new piston and ring and got the barrel replated and this is happening to the piston IMG_1788.JPGIMG_1790.JPGIMG_1791.JPG I bought the motor blown up and rebuilt it and it ran like an absolute dream. Could this be old bits from the crank case that stayed down there from previous blow up? Or is it like pinging that's cracked the piston top ?

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It's not pinging ,that's either bits that have been floating around in the crank area, ,check are the circlips still in the piston.

 

time for a complete rebuilt buddy 

 

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Yes exactly ,and if it was mine I would be replacing or rebuilding the crank with new bearings ,seals etc etc 

Yeah I will probable replace full crank

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Without knowing how the engine previously failed (and to what extent)

you took a gamble on only fixing the top end and unfortunately lost.

 

At this point you need a full rebuild.

Closely inspect the cylinder, pic # 1 might show some damage on the exhaust bridge.

 

If you re-use the head, it will have to be machined smooth or else all those gouges prone to cause hotstops/pre-ignition.

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