Mike,
As a data point that may be helpful to you, all TR250's had
non-adjustable Stromberg carbs. The needle was held in the air valve with a
grub screw, and inserting a special hex tool down the damper hole
accomplished nothing. As a (very) slight silver lining, at least there was
no rubber o-ring at the bottom of the damper to wear out and let your carb
oil leak out....
The carbs for 1969 TR6's were the same way. Look in your TRF TR6
catalog, volume 1, and compare plate AV (1969 carbs) with plate AW (1970
carbs). The 1969 carbs show only non-adjustable needles and grub screws
(items 15 & 16). However, the 1970 carbs list both adjustable and
non-adjustable needles. Later year carbs list only adjustable needles.
Apparently, the switch was a running change in the model year, perhaps when
the type C3292 carb was superceded by the C3365? Does yours still have the
small metal tag on the top cover screw that identifies the exact carb
variant? If not, try inserting the carb adjustor tool down the damper. If
it spins without resistance, the carb is non-adjustable.
I'm getting ready to convert my non-adjustable Strombergs to
TR4-type adjustable jets, which is what the designers intended. Details, as
well as a wider discussion of Stromberg carb adjustment, can be found in
Len Renkenberger's booklet, "Six-Tech", available from his ad in the
6-Pack's magazine (blatant plug).
Hope this helps,
Tom Marincic
CD3574L
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