[TR] TR3A Choke Question

[David P]

Randall is quite correct.. if the piston rises too quickly air flow 
(velocity) across the jet head is lost/decreased and the mixture goes 
lean. The dampers (of which there are different sizes-BTW) at as a 
defacto accelerator pump by keeping the piston from rising too quickly.. 
Hope this info clears up some SU mystery.


On 11/5/2018 9:20 AM, Randall wrote:
>> What kind of oil are you using in the dash pots?  If the oil
>> is too heavy, it may overdamp the pistons, causing them to
>> rise too slowly and momentarily weaken the mixture, causing
>> the hesitation. I find 3 in 1 is about the right weight.
> Actually, it's just the opposite.  Heavier oil makes the mixture go richer
> right after you open the throttle.  Using oil that is too light can cause a
> "lean bog" (like Jim described).
>
> The book actually recommends 30 weight for temps between 40F and 70F; 40
> weight above that.  Optimum for you may vary somewhat, depending on engine
> condition and so forth; but I have always found that performance suffers
> with less then 20 weight
>
>>    The choke cable is hard to pull
>> out.  Takes two ands
>>> to pull out and then twist to lock.  That's to really get the choke
>>> levers to move both jets down.  Is this normal or maybe I
>> need a new choke cable.
> Not normal, but unfortunately rather common.  Did you polish the jets when
> you had the carbs apart?  Originals were supplied polished, but the
> replacements I've seen have been dull.  Dull means a rough finish, which
> greatly increases the friction against the glands.
>
> The linkage also goes together in an odd way.  If you put it together the
> way it seems it should go, it's harder to operate the choke.  The two
> clevises hang out behind the levers, rather than straddlings them.
>
> I like to replace the gland sping (inside the jet housing) and the return
> springs during a rebuild, especially if you don't know the full history of
> them.  It's not uncommon for people to stretch the gland spring out a bit,
> in an attempt to get the glands to quit leaking.  The extra pressure
> increases friction, to the extent that often the jets won't return after
> using the choke.  So then they shorten the return spring.  Both actions make
> the choke more difficult to operate!
>
> -- Randall
>
>
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