lean cylinder 1977 KZ 1000

I picked up KZ for cheap (not running) first thing I did was clean the
carbs, second put in a battery...it fired right up. I fouled the plugs
right away so I replaced them and it ran ok, it was Idling high and
loading at the stop lights. I pulled the carbs again and mechanically
synched em, this helped alot. It idles very nice and the entire power
band is strong, but through the whole process the # 3 plug comes out
pure white and the others are tan to black but not too black. I have
read a few posts about valve problems and I have the service manual,
but I would like to narrow it down first. Any advice would help. Oh
yeah I love the bike, I have wanted one for years, it's in very good
shape the miles say 6700 looking at parts the bike it might be
true..others not.


Chris
Minnesota
1977 KZ 1000
2004 Yam Kodiak

 

I would check the fittings on that cylinder. The rubber boot or the
vaccuum fitting on the boot could be cracked allowing air into that
cylinder. Try spraying some WD40 on the boot in front of the carb while
the bike is running and watch for signs in the exhaust that it's being
sucked into the cylinder. I tended to remove the rubber covers over the
fittings on the and tie them together with some vaccuum hose and small t
fittings after syncing the carbs. It helps smooth idle and make off idle
response smoother.

 

The initial loading up and carboning of the plugs might have more to do
with sticky floats, than with idle mixture adjustment.

High fuel level in the float bowls makes it easier for the engine
vacuum to suck
up excessively rich idle mixture.

Pump gasoline contains carburetor cleaning additives that will remove
most of the gum and varnish deposited by evaporating gasoline. Or you
can clean the carbs quicker using carburetor cleaners that contain
xylene, acetone, and methyl alcohol.

You can mix about 3 or 4 ounces of Berryman's B-12 Chemtool Choke and
Carburetor Cleaner with a full tank of gasoline and ride the motorcycle
slowly to get the cleaner to go through the idle circuits.

B-12 is available in 15-ounce aerosol form or the 15-ounce liquid form.
I buy both, they are about $3.00 a can from Wal*Mart.

A plugged up idle circuit may be what is causing the # 3 spark plug to
be pure white.

Or, the intake valve might be set too tight on # 3 and that cylinder
tends to push air backwards through the carburetor. You may have to
remove the camshaft to re-shim the valves on that model, I don't
remember.

The desireable color of spark plug insulators has changed since leaded
gasoline phased out. Tuners aren't looking for tan or brown anymore.
That was lead fouling anyway. Now experienced tuners are looking deep
into the spark plug with a magnifying flashlight. They are looking for
a narrow band of black soot down where the insulator meets the steel
case.

The KZ-1000 had old fashioned slide valve carbs, as I recall, and slide
valve carbs have the idle mixture screw on the side of the carburetor
body. If you want to lean out the idle mixture, turn the idle mixture
screw counterclockwise to allow more air into the idle circuit.

The idle jet on the # 3 carb might be plugged up. The aerosol B-12 is
good for cleaning small jets once the carbs are removed, and you can
also remove the idle mixture screw from that carb and spray aerosol
B-12 down that hole to clean the passage out.

 

does that one have constant velocity carbs on it/
if so, check carefully for a leaky diaphragm in it.
i had a similar problem with a different model and make.
sam