Here's my grrrr question on the subject... and tryta forgive me for being a **** mechanic, but i also haven't been into this top end yet, so here goes.
The cam followers are only held in place by two #90236056000
Valve Lever Shafts; which, coincidentally, are only held in place by two #90136056001
Screw Plugs that remove from the left side of cylinder head. See the attached pics.
But before I go too far with this, I'm gonna plant something right out front. The 2016 and 2017 rep manuals call out .08 - .12mm on the intake and .13 - .17mm on the exhaust; whereas, the 2018 rep manual calls out .10 - .15mm on the intake and .15 - .20mm on the exhaust. Hmmm... it'd been 8-12 and 13-17 all the way from 2013, according to documentation... then they finally widened it on the 18 and 19 models... Ok, enuffa that.
Back to the point -- I know the docs say the followers are DLC coated, but I'm only assuming they are 'steel', are they aluminum? Can anyone confirm this?
If they are steel, and if they have not worn into those shafts that support them, they could be easily suspended by multiple magnets, while one 'valve lever shaft' is removed at a time, and the shims extracted/replaced. I'm sure you can see what I might be getting at, the cams/chains etc would not even need to be removed to do the deed.
Maybe you have doubts about that being possible, but think about it... If there is 4-6-8 thousandth inches clearance between the rocker and cam with the engine at tdc, the shaft slides out (via magnetic extraction, or is its end threaded?), the rocker is rocked outta the way, the shim is picked out via another magnet and measured, a different shim is installed and [wow go back together].
Also, the Hot Cams 31 shim kit is the one that services this engine. They're 1.85 - 3.2 mm thick shims, 10mm in diameter in that kit, just like the factory parts... and they also graduate in .05 mm, so there really isn't a lot of fine differentiating going on there. What I mean is you need to think "is +/- .05 gonna take me outta spec?" Or maybe a better question might be, do you have a set of diamond lapping files, to do a little customizing on the shims bottom side.
The final thing I noticed was the dif between the 2018 and 2019 duke owners manuals. 2018 was when they changed to a looser valve clearance spec; the very next year, 2019, they apparently did away with the 1000km valve clearance check.
The pictures are captioned, in case they don't make sense at first.