Really high idle

[max]

Hi Dave, good question, if the barrel was set too deep into the cavity the bike would not run at 1800 rpm since the opening would be restricted
( all other things being equal ).
here is the iacv body removed, look at the two openings at the bottom of the cavity and you can see the iacv piston sitting halfway the opening where he points his little finger at;
https://www.youtube.com/watch?v=_asKPXxuHbQ