Hi Rapier.......I am one you can talk to as per the above post I have now over 20k USmiles on my TP Caponord.
You have to be wary of forum posts as not all owners are equal and some guys just should not have bought a complex modern electrotechnical whizbang like a Capo or even Multistrada, S1000XR etc etc. The days of owners messing with 'Can-Bus' equipped bikes are numbered.
There is no problem with the exhaust valve......but that doesn't mean one can't fail. Most of the issues stem from the fact that the dealer must set the valve to the correct position using the Aprilia 'PADS' system.......ie YOU and I cannot mess with those ExUp cables! (what might be of more concern is if your Capo has the dreaded throttle twitch at low rev speeds - test ride is essential to check if this is an issue for you).
If you are game, Capo can be a wonderful experience, but that will depend on how far away your trusted/experienced/interested dealership is from you. (and be prepared for some costly major services at 12,000mile intervals as these are extensive teardowns in comparison to ripping the tank and cam cover off a ZX12....).
I always say anybody should be buying a Capo based on a decent test ride not the clearance price tag......that really applies to all bikes, but especially the Caponord.
Ps, the oil in the airbox was a 2013 model drama - 2015 models should have the clear plastic drain tube showing on the left side above the front cylinder.......I've never had any oil showing in it on my 2014TP. Capo has a fair bit of electronics, but it is basic compared to all the 2016/17 generation models........and I haven't had any issue with this bike that wasn't my fault (eg - I knocked the clutch micro switch which temporarily disables the cruise control.....pushed micro switch back into position and no further problem.......just need to learn what you've got and how to look after it.
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Oh, that reminds me...the US models have a charcoal canister bolted to the LHS front cylinder.......I read that most remove it and the details are on a post in the 2014-2016 forum......