I have been running replacment (used) pistons in both Strombergs on my TR250
for over two years. Replacements have adjustable needles which work great.
Go for it...
Dave Brackin
Tomislav Marincic wrote:
> Triumphisti,
>
> The Zenith-Stromberg CD-SE and CD-2SE series carbs
> are indeed matched at the factory as an air valve, cover, and carb
> body set. Take a look at the top of the carb body, just above the
> throttle butterfly. You'll see a lead plug that covers the "leak
> balancing screw". To quote from the Haynes Stromberg carb
> manual, page 39:
>
> "To compensate for the very small variations in
> component sizes (air valve diameter and body bore diameter)
> due to manufacturing tolerances, an adjustable screw is
> incorporated to provide an additional air bleed between these
> two regions....Once the screw is set, on initial build, it must not
> be altered...The body, air valve, and cover become a matched
> set and neither (sic) part must be replaced independently
> of the other..."
>
> Having said that, I'm running a replacement
> air valve and cover in one carb on my TR250 with "good
> 'nuff" results. Our carbs are worn enough by now that the
> advice might be academic, especially if you've had
> Apple Hydraulics bead blast the soft aluminum (as I
> have). But I would not advocate taking emery cloth to
> these parts on the assumption that the presence of a
> rubber diaphragm makes tolerance issues moot.
>
> Best regards,
>
> Tom Marincic
> CD3574L
> carbs balanced at idle only...
>
> Dave Terrick wrote:
>
> FYI, AFAIK the matched set theory is only applicable to SU carbs, as they
> use no diapraghm for sealing top to bottom. Thus, a machine tolerance
> finish is required!!
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