i just came across a free yamaha dirt bike. how do i figure out what year/ size it is? i could not find a vin but found a number stamped in the crankcase.
That will be an engine serial number. It isn't going to be as useful as the VIN. Look up near the steering head on the fram, thats where they are normally stamped.
Yes, but is isn't the necessarily the engine serial number. Look close at the frame, and do a bit of degreasing. Like Timber said, concentrate on the area around the steering head , especially the vertical part. That is where the VIN is stamped most of the time.