talking of 80x64 i have a spare 360 Rt2 motor set up like that, [why] just because i could. Must get back to it as [do] want to know how it'll run. I used a 250 crank in a 360 cases, set piston at bottom of ports [spacer under barrel], the took ummm--6mm off top. Will run oneday, just not sure how well. I'll report in with the bad news[or good]. Always wondered what size it is so 322cc looks like it. Could have been a piston port RT1 piston [as mentioned] in the TS250 mod. Always thought a good [mod] trick on a DT360A would be an SC500 top end as same base stud pattern & 70mm stroke [way over square] just cases are cast in to edge of cylinder liner where it sits down in cases so could easily be modded. Gosh your mates would wonder what the hell you'd done to it overnight as you wheelie past. I feel another [silly] plan coming on.