These fit the std SS and Monster 38mm Mikunis.......and also funnily enough, Yamaha TDM's, and carby Triumph triples like the Sprint, Trophy etc and the 3 cylinder Thunderbird 900's....... £21.42 each plus postage
So a could not be bothered to remove airbox just to measure and my attempt with airbox one produced 20mm size !? I guess they go where airbox would have linked with carbs? If so airbox out and they should fit as fcr's are linked to airbox with stock connectors. Do you have to change them or just wash/oil them?
If they fit into the std airbox then these should fit Lucasz, as they fit the std 38mm Mikunis...you just blow them out with compressed air and oil them to clean them.