The thing to remember about carb cleaner around Zenith carbs is not to
use it to clean the carbs! That is, most cans have instructions that
tell you to get all your performance back by removing the air cleaners
and spraying copious amounts down the throats.
On Zeniths, this does, indeed, clean a lot of the gunk off of the
insides. It also rots the rubber diaphragm that separates the upper
vacuum chamber from the main throttle passage. They eventually (a week,
maybe) crack, which converts the carburettor from a constant depression
to constant volume model: the more you open the throttle, the more air
you get. You never get a larger metering bore, you never get more gas,
you never accelerate past 3000 rpm.
(Of course, I only read about this -- *I* would *always* clean my carbs
by complete disassembly and rebuild! Yeah, right. Live and learn. :-)
chris
P.S. It actually says something about this in the Moss catalog, in one
of their helpful sidebars. That's how I managed to diagnose the weird
behaviour after the fact.
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