1972 cb350 idle issues

 Howdy folks

Forgive the newbie, but I've got a dumb question that I can't seem to answer
for myself. Here's the thing: I've got a 72 cb350 that wasn't ridden much
over the last 10 years (though it was ridden a bit here and there throughout).


I had a problem with stalling and the left piston not firing until the engine
heated up significantly. So I did the obvious: Rebuilt the carbs -- even
replaced both diaphragms -- replaced the air filters, replaced the points,
set the timing (all by my mechanic, of course).

Both pistons are firing now, but unless the choke is open (minimum halfway)
the bike will stall when idling (ie. sitting at a light). Also stalls
sometimes on downshift.

Is it as simple as adjusting the idle here, or am I missing a more complex
problem? Any help would be appreciated. Thanks much, MW

 mwhyte wrote:


http://www.bikebandit.com/partsbandit/showschematic.asp?dept_id#16300

The idle mixture screw is shown on the side of the carburetor as 8, 8, and 3.

Turning it counterclockwise about 1/4 to 1/2 a turn should make the engine
start idling on both cylinder when cold.

If that doesn't help, remove the screw after first tightening it until it
lightly seats, while counting the turns.

Then spray some aerosol carb cleaner in the hole and reinstall the screw the
same number of turns out from lightly seated that you counted.

If that doesn't clean the idle circuit out, try putting about thee ounces of
Berryman B12 Choke and Carburetor Cleaner in a full tank of gasoline and
going for a slow ride to clean the gum and varnish out of the carbs.

Another possibility is that the floats are set too low, or the float valves
are gummed up and stuck shut.

--
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 Albrecht via MotorcycleKB.com wrote:

I'm curious whether synchronizing the butterflies/vacuum would have any
effect (assuming the carbs can be balanced on this bike).

 paul c wrote:


Mechanic$ in $tealer$hip$ often recommend carb $ynchronization ju$t before
Chri$tma$ and April 15th. ;-)

Seriously, you cannot synchronize dirty carbs, and CV carbs with shafts
joining the two butterflies don't go out of synchronization as easily as the
older slide valve carbs with multiple throttle cables.

--
Message posted via MotorcycleKB.com
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As you suggest, it might be as simple as adjusting the idle SPEED, since
that's one of the things the choke mechanism does (raises the idle speed).
Do you have a tach?
If so, what IS the idle speed?
Probably should NOT be below 1K.