Proably a slight case of the blind staggers. At the very least you'll
have to redo your jetting--you will reduce the air velocity at lower
engine speeds and probably lean out that range substantially. You're not
likely to see any real improvement in performance except at full throttle
and near-max rpm. If that's what you're after, then go play--at the worst
you'll be sticking the old chokes back in again.
As far as going to higher altitudes, you won't see any improvement, in
fact it will be harder to improve the tuning. At ailtitude the air density
decreases and so you generally wind up rich (though some carbs with a high
bleed air characteristic actually go the other way and become rich).
Decreasing air velocity with a bigger choke makes the jetting less
predictable--the transition from jet to jet is not as smooth (idle to air
to main). Very obvious with two stroke bikes--the ones with small carbs
relative to displacement are far less sensitive to air density than the
ones with big carbs.
Carbs are a very approximate device--getting the air and gas mixted at the
right ratio depends on having just the right atomization happen over a
wide range of air veloicities in the carb throat. It's amazing that they
work at all.
-----Original Message-----
From: Joe Curry
To: Friends of Triumph
Sent: 7/21/2001 1:39 PM
Subject: Weber Chokes
All you Weber experts out there, Please answer this for me.
I have 40 DCOE carbs on Tiny Tim, the Autocross Spit. It has 30 mm
chokes installed currently. I have a set of 33 mm chokes in hand and am
wondering
what effect installing them without making any other changes will have.
In planning the trek up to the lofty heights of Breckenridge, I want to
be prepared to tune the carbs for the rare air up there.
I eagerly await your replies!!
Regards,
Joe (C)
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