Optimal CO setting on a late DX 1.8 Cabby

Guys, what CO do you have your DX engines set to?  I've recently bought a 1991 Sportline Cab which ran with a slightly high idle of 1050rpm. I backed off the idle speed to 850/900 and the CO has gone up from 1.1% to 1.8%.  I used to run my DX tintop at 1.0-1.5%.  What do you guys recommend?

Also, my tintop DX has a tube for the CO adjustment on the metering head, while the Cabby just has a hole in the same position - is this correct?

1.8 will be fine, anywhwere between 1.5-2.0 is what i set em to.

some will have the hole, some have the tube, makes no odds really. ideally there should be a wee cap as you're getting unfiltered air thru it, but I never bother. (its still metered air mind, so its not like an air leak)

Cheers John