older K&B aircrat engine questions

[jon19]

i recently ran into a few older K&B engines (at least i think there older) but i cant find a model number or anything to tell what type it is. i was wondering if theres someplace im not looking the only thing that i can find is the K&B logo on the side of cylinder head and carb, the made in usa stamped on the other side of the head and a 91: stamped on the back side of the crank shaft case if theres any way for me to tell what type engine this is please let me know

[jon19]

k think i found the series looked at the parts list for all of them and it looks exactly like the K&B sportster .20-.28-.45-.65 series, now i need to figure out exactly which one it is theres a 91: stamped on the back cover and thats all i can find......so far maybe ill try to rip apart one of the worse off ones and see if i can find anything else

[MECOA]

This a Sportster .65

The reason for the 91 was the year the casting was made. For some reason the diecaster decided to mark the parts to identify them. He picked a very bad way to do ut.