triumphs
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Re: [TR] TR3A Choke Question

To: Randall <TR3driver@ca.rr.com>, 'Jim Henningsen' <trguy75@gmail.com>
Subject: Re: [TR] TR3A Choke Question
From: David P <frogeye@porterscustom.com>
Date: Mon, 5 Nov 2018 16:41:50 -0700
Cc: 'triumphs' <Triumphs@autox.team.net>
Delivered-to: mharc@autox.team.net
Delivered-to: triumphs@autox.team.net
References: <008a01d47499$5783a2d0$068ae870$@gmail.com> <5B79DF04-10F8-481D-B6D7-C11030B5CA47@albiontechnical.com> <AE846037AD2D44809715F7383DE0A1E3@RYPC>
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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
>
>
> ** triumphs@autox.team.net **
>
> Donate: http://www.team.net/donate.html
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-- 
Porter Custom Bicycles 2909 Arno St. NE Albuquerque, NM. 505-352-1378 My World 
go here: WWW.PORTERBIKES.COM/



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    <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.<br>
    </p>
    <br>
    <div class="moz-cite-prefix">On 11/5/2018 9:20 AM, Randall wrote:<br>
    </div>
    <blockquote type="cite"
      cite="mid:AE846037AD2D44809715F7383DE0A1E3@RYPC">
      <pre wrap="">
</pre>
      <blockquote type="cite">
        <pre wrap="">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. 
</pre>
      </blockquote>
      <pre wrap="">
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

</pre>
      <blockquote type="cite">
        <pre wrap="">  The choke cable is hard to pull 
out.  Takes two ands
</pre>
        <blockquote type="cite">
          <pre wrap="">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 
</pre>
        </blockquote>
        <pre wrap="">need a new choke cable.
</pre>
      </blockquote>
      <pre wrap="">
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
</pre>
      <br>
      <fieldset class="mimeAttachmentHeader"></fieldset>
      <br>
      <pre wrap="">** <a class="moz-txt-link-abbreviated" 
href="mailto:triumphs@autox.team.net";>triumphs@autox.team.net</a> **

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</pre>
    </blockquote>
    <br>
    <pre class="moz-signature" cols="72">-- 
Porter Custom Bicycles 2909 Arno St. NE Albuquerque, NM. 505-352-1378 My World 
go here: <a class="moz-txt-link-abbreviated" 
href="http://WWW.PORTERBIKES.COM/";>WWW.PORTERBIKES.COM/</a></pre>
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