Norbsa, your reply would seems to describe tips for using a Gunson's 'Colortune'?:
http://www.carbtune.co.uk/colortune.html
A (Morgan) 'Carbtune' is a device for carb balancing:
http://www.carbtune.com/
Per G said:
what procedure is used to tune your bike with Carbtune.
The basic procedure is fairly straightforward (obviously read the Carbtune instructions first). The object being to synchronise the slides so the intake vacuum readings of both inlets are (more or less) identical at idle (throttle stop adjustment) and that both throttles rise by equal amounts off idle, the result being that (theoretically) both cylinders should perform equally.
So, (after you've read the instructions) you will need to hang the Carbtune from a convenient position where you will be able to see it while doing the adjustments (L/H handlebar grip)?) using the re-usable ty-wrap supplied, so that the hoses can easily be connected to (in the case of a Commando) the balance pipe stubs, the Carbtune adaptors (M5 & M6) in the kit are not normally required, because the rubber pipes should push straight onto the balance pipe inlet stubs (a little lubrication will help).
KEEP THE TUBES ROUTED AWAY FROM THE EXHAUST PIPES.
For Amal carbs you will probably need to use the Carbtune in the 'upside-down' position (this method is mentioned in the instructions) as some engines don't give very high vacuum readings, so the Carbtune needs to be inverted to show a reading, so you will be reading it upside down.
Make sure there is some cable slack at each carb.
Start up, and allow the engine to warm up.
Once the engine has warmed up adjust each throttle stop screw until the two indicator rods are showing equal readings, and also set the screws so the idle speed is correct.
Remember, the carb with the lowest vacuum reading has its throttle open more than the other one.
Then open the throttle slightly, while observing the rods, the rods should move more or less together?
With the the throttle held steady off idle the rods should show equal readings?
If not, then the use the cable adjusters to set them so both are equal.
Recheck the whole thing by blipping the throttle, you may find that if the carbs are a bit worn that the readings will tend to vary a bit each time, hopefully it won't be by too much?