just spring washers under the nut is sufficient to stop the carb nipping up,which i have had experience of at full throttle on my triumph metisse,of which i had to part company with,going down hill at a scramble,over tightening will distort the body,brass slides always seem to have tight spots when you first fit them,be careful putting R in your fuel,it may smell nice but it can also sink straight to the bottom of the tank,and block the tap,its a bit difficult to pick ur bike up and shake it to mix it up,that was an old wifes tale,putting R into the fuel to lubricate the slide,of which i think comes from blokes going to the speedway and wanting their bikes to smell the same as the speedway bikes.