OK, yours is a model 4371, not a 4423, and was produced from ’41-’47. It is an opposed twin while the ’48 and later 4423’s were alternate firing inline twins. Two completely different animals with the same name.
Yours is a nice motor by the way and it appears to be in good condition. With the painted tank and emblem on the front, I’m guessing it’s a ’46 or ’47.
