"Float Drop"? '82 KZ1000

Seems like I've done everything I can think of to clear up the low-speed
rich condition on my CV carb for cylinder #1. Disassembled, cleaned, new
o-rings, new idle mixture screw, checked fuel height in the bowl via clear
tube, etc.

The only thing I can think of is that although the fuel level check shows it
to be about right, the float is still allowing too much fuel into the bowl.
The float tab is at its limit - I can't adjust it anymore without it losing
contact with the shut-off needle while the float is in the fully closed
question.

My question is: Do these floats "grow" in density (i.e. get heavier) with
age and crud absorption into the float material? I believe they're the
original (and are not brass), but the experiment to replace with new is not
cheap.

Per plug read the rich condition is pretty even across all 4 carbs, but #1
is the most sensitive, often fouling at start-up.

Thanks,
JpnseFours

 

low-speed rich condition on my CV carb for cylinder #1. Disassembled,
cleaned, new o-rings, new idle mixture screw, checked fuel height in
the bowl via clear tube, etc. The only thing I can think of is that
although the fuel level check shows it to be about right, the float is
still allowing too much fuel into the bowl. The float tab is at its
limit - I can't adjust it anymore without it losing contact with the
shut-off needle while the float is in the fully closed question.

I'm trying to make sense out of that last statement, and fail to do so.
Are you bending the tab the right way?

If you want to adjust the float level while you have the carbs upside
down for measurement with a caliper, you bend that tab *down* toward
your work bench to lower the fuel level, and *up* toward you to raise
the fuel level...

Then you measure the distance from the float bowl gasket surface to the
bottom of the float, which is the top of the float with the carbs
upside down...

Maybe there's a tiny speck of crud on the fuel shutoff needle valve
seat? When you take the carbs apart for inspection, look at the seat
with a magnifying glass, you might spot the problem there...

Also, look at the needle jet (the brass tube that the jet needle slides
up and down in) to make sure the orifice hole is perfectly round. If it
has worn egg-shaped, it will pass extra fuel at small throttle openings
when it's not supposed to pass very much fuel at all. And, check the
jet needle for excessive wear high up on the needle. The egg-shaped
hole in the needle jet and the wear on the needle are especially common
on motorcycles with semi-downdraft carburetors, like the Yamaha
FZR-1000 models that can wear out needle and needle jets in a few
thousand miles...

Lastly, I recommend checking the starting enrichener plungers to be
sure they aren't stuck slightly open, allowing excessive fuel to travel
through the starter port which bypasses the throttle butterflies...

with age and crud absorption into the float material? I believe they're
the original (and are not brass), but the experiment to replace with
new is not cheap.

In my experience, composition floats don't get heavier...

but #1 is the most sensitive, often fouling at start-up.

Does the exhaust pipe emit *black* smoke? Does the engine stagger,
going "toot-toot toot-toot" until the rich fuel air mixture clears out?
That's what rich idle mixture sounds like...

Are all the parts in place on the idle mixture screws? There should be
a spring, a tiny washer and a tiny rubber o-ring, in that exact order,
installed on the idle mixture screw before you screw it into the
hole...

 

With the carbs on the bike, I'm bending the tab "up" (toward the gas
tank/seat). However, the tab has already been bent so far "up" that if it
goes any more it will slip past the end of the spring-loaded end of the
shutoff needle valve when the float floats "up" in the gas.

Right now I'm being lazy and trying to avoid taking the carbs back off. With
the cold weather the rubber connections are a bear to work with.

Possible crud - the needle valve and seat are new (less than 1000 miles).

The enrichener plungers are my second suspects. Given your experience that
composition floats don't get heavier, the enricheners have now become my
prime suspects.

Black smoke off idle (accelerating) - once it's at speed (6K rpm for a few
minutes prior to a plug chop) the plugs are a nice tan across all four.

Now if I can just figure out how to tinker with the #1 enrichener and make
sure it's closing all the way....

 

tank/seat). However, the tab has already been bent so far "up" that if
it
goes any more it will slip past the end of the spring-loaded end of the
shutoff needle valve when the float floats "up" in the gas.

Is the fuel shutoff needle valve actually moving up and down freely, or
are you just pushing against the spring with the tab on the float? It's
possible for gum and varnish to build up on the edges of the needle
valve and make it stick...

make
sure it's closing all the way....

Do you still have an airbox on your KZ-1000, or have you replaced the
airbox with K&N separate filters?

If you have the K&N's it's simpler to remove the filters. Then, when
you look at the air intake bell, you will probably see the starter air
inlet on the left side of the carb and the idle mixture air intake on
the right side...

If the starter plunger is leaking gas/air mix at idle when you think
you've closed it, blocking the starter air inlet passage with your
finger should shut the air flow off...

If the engine speed changes with your finger over that hole, you
probably have a leaking plunger or it just isn't closed all the way...

 

Stock box...

That's a good idea - I can get at the starter air inlet passage pretty
easily. I'll give it a try.

Thanks