250 or 220 motor

[shift_79]

I found a parts snowmobile in a junk yard, and it is in very poor condition, is there a way to tell what size engine it is, or what model? I have a serial number from the engine. Do the 250 motors look the same as the 220's? It looks the same as the 250 motor, and has the same carb on it as the one i already have. If anyone knows how to tell, please e-mail me about it, thanks for your time.
Steve