I hear you there Bud... getting the dual vacum gauge to function may require
blocking
off the balance pipe between left/right manifolds, otherwise backpressure
may interfere with true gauge reading; inline restrictor would dampen needle
movement.
The bing carbi is not too different to the stromberg; age/grime/carbon blowing
back into the inlet manifold from the combustion cylinder will eventually result
in wear between carbi piston and its bore; so over time there would be slight
discrepancies between operational height at various rpm due to slight vacum
differences ; so the more carburettors used the greater the opportunity toward
variation in mixture; and the way each carbi is balanced off against the others
is by raising each piston manually and observing changes at idle or set rpm
(as with SU or Stromberg tuning)... It doesnt take much to setup a minor
harmonic
vibration. This is why a dellorto can offer superior performance; from dellorto
its onto the world of mechanical or electronic injection and all have
their endemic nuances.
Another usable diagnostic is monitoring all individual exhaust headers at tuned
lengths from the exhaust valve; compare and contrast...
Personally, to get multiple constant depression carbis to run in perfect unison,
other than buying s new matched pair, everything needs to be set up equaly on
a bench down to .0005 accuracy, all pistons need to be checked and equally
balanced,
and then piston heights need to be equally set at a uniform air flow,
and then it all needs to be setup for smooth idling... It can literally take
weeks; and you might get 200, or 2000, hours of joy... somewhere you just need
to draw the line at Cost/Time/Benefit. After 40 years making internal combustion
engines run smooth first thing I would do is throw both carbis in the bin,
unless you are a diehard purist, and fit good quality injection.
All things equal the rotax is a really really sweet powerplant which has left me
very very impressed by... as is, could probably benefit by having an O2 sensor
and readout retro fitted for inflight diagnostic.
And Bud is right there; get your fuel supply done and move onto ignition
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