Hi,
I don't think anyone has warned about turning the mixture adjustment too far
lean (counterclockwise), which causes the whole needle assembly to fall off
the end of the threaded adjuster that you turn with the special tool. Easy
to do and not easy to tell you've done it, except that from then on, you get
no reaction to turns of the tool (guess how I know).
To get the needle assembly back on, hold the needle assembly up in its
proper place and turn the adjuster as if to richen (clockwise) until the
threads
catch. I can't remember anymore how many turns from full rich it takes to
drop the needle assembly off the adjuster (switched to HS6's at least 10 years
ago), maybe someone else can say. It might be worth dropping the needle off
once while counting turns from full rich, just so you know what the maximum
number of turns you can make (without dropping the needle off) is. I did find
it helpful, If I recall correctly, to remove the piston from the carb body
when reattaching the needle assembly this is easy enough to do, just takes a
screwdriver), but I think it's possible to reach into the carb throat and get
the needle assembly back in place to catch the threads of the adjuster without
disassembling anything. The Haynes ZS carb manual has the clearest
illustrations of the these carbs, but you can get by with either the Haynes or
Bentley TR6 manuals.
The other issue that I think hasn't been mentioned is the importance of
getting the outer part of the special adjustment tool securely in place. The
little protrusion on that part of the tool must be seated in a little notch
down
inside the carb. It's quite obvious when it engages as you gently turn the
outer part of the tool. If you turn the allen key without first securing the
outer part of the tool, you will tear the rubber diaphragm in the carb body,
which then must be replaced, as the carbs work very poorly when there is any
air leak past the diaphragm. So, seat the outer part of the tool positively
and hold it from turning as you turn the allen key. This keeps the allen
key from also turning another part of the carb that will in turn twist the
diaphragm and damage it. (Once again, guess how I learned this.)
Jim Knight
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