There were several bikes that used the same cup:
EL250-B2 (Eliminator) (198

EL250-B3 (Eliminator) (1989)
EL250-E1 (Eliminater 250) (1991)
EL250-E2 (Eliminator 250) (1992)
EL250-E3 (Eliminator 250) (1993)
EL250-E4 (Eliminator 250) (1994)
EN500-A1 (Vulcan 500) (1990)
EN500-A2 (Vulcan 500) (1991)
EN500-A3 (Vulcan 500) (1992)
EN500-A4 (Vulcan 500) (1993)
EN500-A5 (Vulcan 500) (1994)
EN500-A6 (Vulcan 500) (1995)
EN500-A7 (Vulcan 500) (1996)
ZL1000-A1 (ZL1000 Eliminator) (1987)
ZL600-A1 (ZL600 Eliminator) (1986)
ZL600-A2 (ZL600 Eliminator) (1987)
ZL900-A1 (Eliminator) (1985)
ZL900-A2 (Eliminator) (1986)
Probably from something in the '90s. Not sure how the gears vs tire size work out, it may still function correctly. Since the same speedometer went on multiple bikes, I would guess that the gearing at the speedometer drive was changed to compensate for tire/rim size and the actual speedometer would work with the any correct combination.