Yep, that's a B607. Looks like all you are missing is the tank. The serial number looks like I 45648. The I prefix was used right before the war and then again right after the war ended in '45. Your bike is likely a '46. Show a pic of the kickstand and I'll be able to tell if it's a '46. My B6 in the avatar looked about like yours when I started on it. Gary