1989 yamaha exciter 570 melt down

[YamahaSXR700]

ive posted a forum yesturday, blew the engine in my exciter, and i found the problem, theres 2 oil inject lines that goes to the gas line from the pump, and one was cracked bad on the pump so i took pictures here it is if u can see it and forgot to mention this, my pistons are groved with the number 25 on top? i beleive its bored out, but how much ?

 

[RelicRuss]

25 staping means .25 mm or .010" .
you will need to go to .020 or maybe .040 in worse cases. Wiseco makes pistons up to .060"

 

[Brit44Aldo]

Make sure your machinest uses the piston to cylinder clearance of the pistion manufacturer. Forged pistons and cast pistons require different clearances.

Put a Wiseco piston in a Pz480 at 0.0025" clearance and the engine will not rev properly untill the piston wears to the recomended clearance.

 

[YamahaSXR700]

iam planing on putting spi piston kit on it 1 thow over

 

[YamahaSXR700]

but the cylinder is not gouged its not scored, its only melted piston on it

 

[corcan1]

i would bring the cyl to a machine shop and have them check it over.
might be able to get it cleaned up.