Gary,
The DSP044 springs that come with the Dynojet stage 1 and 7 kits have
about 1/3 the compression resistance of the stock springs, (PA
measured them ... what an animal ...). You are right .. everything
else being equal .. the lighter spring will cause the slide to be
retracted more than with a stock spring. The lighter spring, (usually
used with the "larger" slide hole in the Dynojet kits), will result in
a more "responsive" slide action. Mixture adjustments should be made
accordingly ...... Of course .. a "steeper" taper on a needle will
allow more fuel to be used for the same slide retraction distance ..
everything else being equal ..... so there are a lot of variables to
consider.
Light slide springs should have no affect on top end horsepower ...
obviously .. as a slide should be fully retracted at this point and
you should be running only on the main jet anyhow .......
If someone chooses to "cut" or "tie back" a spring to reduce the
pressure it exerts on the slide then it is of course important to make
sure that tension is as equal as possible for all of the carburetors
and that any mechanical "tie back" does not interfere with the
movement of the slide. A common mistake is to not get the spring
seated properly on the outside of the three fingers cast into the
slide cover on the carbs ... This will really drive you nuts ..
because the slide will operate normally and only bind at the very end
of it's travel ... it is easy to check ... by depressing the slide
with your finger ... if you feel a slight "crunch" at the end .. the
spring is binding and not seated properly in the slide chamber ... the
affected cylinder will never see "top end" with the rest of it's
buddies.
Also .. it is important to remember that the slide is sensitive to
intake air flow resistance. Any reduction in resistance will make it
much harder for the slide to open .... This is where the "lighter"
spring is not just neat to have .. but a requirement. Anyone who takes
their "Y" off on a stock bike will notice a loss of mid-range
performance unless they make up for the resultant reduced slide
retraction ... and a lot of times they accomplish that by putting a
shim under the needle etc .. which is fine. As additional reduction
occurs .... with more hacksaw to the airbox .. individual filters ..
less restrictive filter element etc .. they will find that they can't
get the slides open enough to get into mid-range ... hitting a wall at
4-4.5K etc ... Taking the top off of the airbox or putting individual
filters on a stock bike is a good example .... as the bike will barely
run off idle ... any attempt to open more than about 1/4 throttle will
cause the bike to nose dive ............. IMHO ......
campbell
----- Original Message -----
From: "Gary Rathbun" <[EMAIL PROTECTED]>
Subject: Re: Carburetor Questions
> snip <
> What is the main purpose of tied (or weaker) diaphragm
> springs? Doesn't seem like it would change the mixture,
> because even though the needle may be retracted further
> for a given throttle setting, the air passageway is also bigger.
> So the effect would be like you had the throttle open further
> than you actually do. Thus, "wide open" and running on mains
> would occur at a lower throttle setting; is this correct?
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