carb size?

[josh31]

I bought a Laeger YZ the other year and it came with a few boxes of parts. I have since sold it and kept a few parts to sell. I have a carb and don't know what size it is. I think it is off a YZ 400 or 426, but not positive. Where or what do I measure to determine the size of it. It is a FCR.

Thanks.

[kawiefan]

The 400 & 426 came with a fcr 39.