I Need a Dt360A piston!

That's wonderful news! Thank you for responding. I'd love to purchase one and a ring set from you once I figure out what size I need exactly. I just read the service manual and did not realize that Im dealing with a .045mm piston clearance. I will not be trusting my caliper measurements from now on and am going to take the Jug to my machinist tomorrow to get a proper measurement😂.

Unless, would it also be an option to put another .020 RT2 piston back in to avoid having to bore? Do you have any of those on hand? Please tell me if that's a dumb idea or not, im just spitballing here and open to your words of wisdom.

This piston and bore look very fresh, just the crack on the piston skirt that has me concerned. Thanks!

That piston you have, appears to be an older Wiseco brand piston.

I don't have any of those in stock ... except for a 4th oversize, which is much too large.

Having a machinist measure and advise you is a good idea.

A OEM 2nd over Yamaha piston might fit if the machine shop just hones the cylinder a little bit . . . until they get the correct clearance. A new 2nd over Yamaha piston measures exactly 80.5mm.

Speaking of clearance, I wouldn't go any more then .04mm (.002") clearance with a genuine Yamaha piston ... In fact, I even bored my own DT360 to only .0016" clearance.

I bored all of my customers DT360's to .0018" clearance.

Whoever you have fit it, make sure they also chamfer the edges of the port edges, so the rings don't snag on the sharp edges of the ports. A good machine shop should know this.