Use of Carbtune(2008)

Reviving this old thread on using the Morgan Carbtune. I was having trouble getting my new premiers dialed in. As I've no proper experience working with dual carbs (was running single Amal on my 850 most of past 3 seasons of ownership), I just couldn't know for sure which way to be adjusting things and was likely going well off the reservation.
The Carbtune Pro was very reasonably priced as 59 Pounds plus 8 more for Royal postage from UK. Got to west coast of Canada within 10 days...no duty and no tax (usually hit or miss or due to total over a cetain point).
Got it all hooked up, right side up (can be used upside down to give better response for lower vacuum level bikes). Right away I could see left side showing way lower rod position (thus less vacuum). Tweaking air stops got both sides even...but had to think it over a bit that the faster air flow (less-open slide) means lower air pressure, higher rod reading. Then with a few higher rev holds, noted again left side much lower rod than right. Found left side cable adjuster needed quite a lot of slackening to get rods to stay in unison when throttling up. All these adjustments were done immediately following dowel movement evenness and slide movement/max position checks. I think using drillbits/dowels for balancing is just a proxy as it cannot take into account real air flow, just the physical characteristics of the slides/cables....which in the real world are not identical. Also wonder if having the choke slides out, leaving big holes in the throttle slides, giving weird air flows etc., has a significant role here.

Initial Carbtune dial in was without air cleaner attached and vacuum pipes attached at the manifold balance tubes. Re-fitted air cleaner. No appreciable difference in balance, though needed a bit of idle stop adjusting (done evenly). Had heard the balance pipe going back on would mess up the idle point again but found this not to be a problem on my bike.

At least now I have a valid, repeatable starting point for further run testing. Really seems to be a good thing to have for a rookie Commando owner.

Any tool or procedure that requires judgement requires experience. When you consider that good judgement is, usually, the offspring of bad judgement pray that your experience comes at the least cost.

I use a TwinMax. Unlike a set of "sticks", palms behind silencers, ears and butt dynos this instrument requires no judgement, it can be used on any engine with 2 or more cylinders. If you think it might have a bias simply switch vacuum inputs, any error in the instrument which quickly become declassified.

Best.