The clutch lever feel on my second-generation 2009 Aprilia RSV keeps going spongy. I’ve topped it up a few times, but I can’t locate the source of the leak.
If the leak isn’t obvious, it is most likely to be the seal in the clutch slave cylinder. Most of the leaking hydraulic fluid will be ‘disappearing’ into the sound-deadening foam on the inside of fairing, and the rest will be lubing your chain.
All Aprilia V-twins use the same slave cylinder design from the 90s to 2009 and it’s easy to service. Once the bodywork is off you’ll see three bolts holding the slave cylinder onto a spacer and the crankcase. Undo these and the slave cylinder piston will be slightly protruding. Pull out the piston with your fingers and fit the new seal with rubber grease on inner and outer seal edges before bleeding air from the system.