hi
I own quite few rossi engines, if you're not sure which motor you have, axe rossi website has alot of charts for their engines, but the 53 rossi is actually a stroked 45., which is a bored out .40, nice thing is if you ruin a .40 sleeve and piston, just replace it a with .45 sleeve and piston, and you ready to go, you can ask for a much higher timed sleeve as well.....
