I´ve out of the loop down here in San Miguel de Allende but here is my input.
I installed a 41 mm FCR about 10,000 miles and 3 years ago on my 99 640 lc4e. I am very happy with it. Here is my setup. (BTW, I live at 5500 feet and ride to 13,000 +)
OBEKR needle in middle position or one leaner.
45 pilot jet
squirt time at the minimum possible about 1.5 seconds if I recall correctly.
modified KTM EXC exhaust muffler with stainless screen in place.
16:42 final drive (I have a 17 inch rear wheel though)
Bike works fine from slow to fast speeds
will do all Colorado single track stuff with ease and still pull 100 + mph inidicated
Motion Pro cables SUCK.
I use stock cables and they work much better with less throttle resistance.
The bent piece of steel tubing on the Mikuni cables is not perfect though but can be slightly straightened for the FCR application. Careful though as it will crack. EVen cracked these cables are worlds better than the overly resistive (friction) MP cables I was sent by Sudco.
Carb is a tight fit, but not a problem. The accelerato pump chamber is close to the header but again not a problem. Install carb on slight angle to clear top frame tubes and header on bottom.
Hope that helps, Esteban
(Party time real soon)