Should I Reuse Piston in Rebuild

[SouthCarolina1]

I have a 1989 115hp 2-stroke Yamaha that I am rebuilding. One cylinder had 50 psi and the other three were at 128-130 psi. The block and camshaft are at a shop being cleaned and inspected. I am prepping the other parts for re-assembly and I ran into a snag. One of the piston heads that had good compression, has two batches of light scoring but none on the sleeve. Would you just clean it up and reuse the piston OR should I get another one (would buy another used one off of ebay). Assuming cylinder doesnt need to be bored. See pictures

 

[robert graham]

Looks pretty darn good to me...maybe a Scothbrite pad to remove those scuff marks and re-use it, as long as it measures O.K. for clearance with cylinder.....There should be a clearance specification in your book in thousands of an inch between piston outside diameter and cylinder inside diameter.

 

[gm280]

Camshafts? This is a 2 cycle isn't it. Did you mean crankshaft? :noidea:

I also don't see any need for new pistons. But that really depends on the bore. If the bore is okay, new rings and gaskets and reassembly it. JMHO

 

[SouthCarolina1]

GM280 thanks for correcting me. I meant to say crankshaft. I have the Yamaha service manual for the motor and I'm waiting on the tool for measuring the outside diameter to arrive. Ill let yal know the results.

 

[SouthCarolina1]

Piston sleeves miked within tolerance but two of the four piston heads were below tolerance. It was the two pistons with scoring. One was right on the line and one was .001 under tolderance. So I am replacing both.