CCP etc.

["Tom Brown" <tbrown@xxxxxxxxxxx>]

Bobs:

> I keep the brass screws closed except to open one up enough to
balance the idle.  I think the left one is open about a quarter turn at
the moment.  Air running through the bypass screws is not metered.  I
figure, how can the computer measure proper mixture if there is air not
being metered?  Just measured the tps at 0.307 volts.

>Bob Hadden '98RS, '62R27

Leave the brass screws open a little!

I've messed around quite a bit with different settings on the brass screws.
I've found that my '99RT didn't run as well in the upper RPM ranges with the
brass screws closed.   It should work, but it just doesn't seem to for some
reason.  I think maybe the turbulance in the throttle bodies is too high
with no bypass air relieving it.   I needed at least 1.25 turns to get the
thing smooth in the upper ranges.  With the screws closed, it feels sort of
choked off as if it had a dirty air filter or something blocking the
exhaust.

I favor setting the idle stop screws with the brass screws all the way shut
(really low RPM and a pain to do) to assure that the blades of the butterfly
are parallel at idle.

I also like to set the TB cable synch with the screws closed for the same
reason, then I open both brass screws up equally at least 1.25 turns and
check synch again.   It should be the same, if it's not, I change one brass
screw a little, not the cable setting.   When the blades of the butterflies
are parallel, you get the widest RPM of in-synch running without rough
spots.    Turning the brass screw at the end may effect idle smoothness a
tiny bit theoretically, but it's not perceptable in my experience...we're
talking 1/8 to 1/4 turn here.

If, after doing all this you need to adjust the brass screws more than 1/4
turn, you probably have some blockage in the bypass orifice.  Just remove
the screws and spray some carb or FI cleaner in the hole and clean the
screws.

In order for Bob Hadden to get his bike to idle right with the screws open,
he'll need even lower TPS voltage.   He can try opening the screws 1.5 turns
and just giving his bike a run to see if there's an improvement in the high
RPM behavior by just putting up with a high idle for a bit.    I think he'll
see what I'm talking about.

- -TB

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