Hey Iam new here trying to get some help. I built a ratrod bike from parts laying around. I found a motor laying around I do know it is a yamaha 400 but I dont know what year or exact model. How do I figure this out. Any help please so i know what engine to buy parts for. It runs now thank god.

There should be an engine number stamped on right hand side of motor.

You can find out year etc with this.

Yeah I got the engine number but i not sure how to break it down to what numbers mean what.

You can tell the year by the first few letters.

If you haven`t got an owners manual, post the first few letters up and someone will tell you.