I may have an extra piston, I bought a 1971 MT1 with extra parts and was in such a hurry (life!) that I can't remember what was in the boxes of parts exactly, I know there were a couple heads, tailight brackets, and gears etc... Not sure if I will keep it, too many projects. Man. I've gotta get my priorities straight, there was a day when I would've stopped what I was doing and mentally cataloged every nut and bolt right then and there, lol. PM me later if you like. They are really fun little bikes, surprisingly powerful. Nice road bike you've got there.