No doubt about it:
Today we are spoiled by the neat electronic stuff that makes our lives easier.
I've had dual Webers and dual Hollies and frankly, I find the Bings to be very
simple, but they wear and adjust differently than venturi carbs. If the Rotax
engine runs smooth so that you can easily read the ignition modules at all RPMs
the Bings last forever. If the engine is always shaking, the carbs will be
trashed soon. Balancing the carbs is straight out of the Rotax manual and now
videos. There should be no excuse for how to do a carb balance by the book,
but that feel and sound is most important however, that ability some just never
get as there are too many things going on in an engine. I don't think its
skill as much as research, observation and patience to determine a root cause
of a problem. You great mechanics study engines and tinker and never give up
no matter how hot, miserable or hungry until you understand and then solve the
problem. The old Thomas Edison approach, just keep on trying. Of course, as
I get older, just remembering what I did is slipping away.
I wish we just had a simple SDS fuel injection with a simple pot lever arm for
a mixture control and a knock sensor. Ah to dream.
Best Regards,
Bud Yerly
-----Original Message-----
From: owner-europa-list-server@matronics.com
<owner-europa-list-server@matronics.com>
On Behalf Of Area-51
Sent: Monday, September 20, 2021 3:44 PM
Subject: Europa-List: Re: Carb Balancing
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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