The mixture is set by adjusting the mixture nuts on the bottom of the carb.
The needle determines the mixture profile. That is, mixture at different
carb openings. Don't mess with the fuel pressure. They are designed to
operate at 3.5 pounds (more or less).
Defiantly sounds like you are running lean. Not a good thing at all. Too
lean raises chamber temperatures and does all kinds of nasty things to your
engine. Either learn to set them yourself or find someone who can. Running
lean is bad news.
Here are a few links that you can take a look at regarding the care and
feeding of SU's.
http://www.team.net/www/morgan/tech/tuning.html
http://web.tiscali.it/no-redirect-tiscali/abosco/moto/carb/su2.html
http://www.jetlink.net/~okayfine/su/sumain.html
What part of the world are in? There might be someone in the vicinity to
give you a hand.
Best regards,
Fred Schroeder
Denison, TX
SRL311-13359
TDROC
Reg e-mail mail@schroeder-family.us
Home page http://schroeder-family.us
----- Original Message -----
From: "Stephen Wan" <Steve@olsonarchitect.com>
To: <datsun-roadsters@autox.team.net>
Sent: Wednesday, November 26, 2003 10:33 AM
Subject: Re: Coughing/hesitation problem
> I tend to run with a little choke when city driving. Helps keep the
pinging
> to a minimum when accelerating. I imagine I'm running a little lean, but
I
> hesitant to start messing with a carb that runs well otherwise. Any other
> way of richening the mixture w/o changing needles? Higher fuel pressure
> perhaps? I've tried recurving the distributor and various timing
settings,
> but it looks like Boone's elect dizzy may be the cure. I do notice that I
> can chirp the tires from a start with the choke on, but not off.
> Steve
> 70' 1600
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