RE: Rossi .81 ducted fan
Definitely a BVM (KBVM )...but just exactly what size? My guess is .81 as well.
The backplate/carb and the drive spool is virtually identical to my .91's...The .91/.96 were made by Nelson and look VERY different. (.96's had purple heads and drive spools )
There was/is a K&B .82 but I think the same basic engine was used to make the KBVM .81...correct?