GPZ-305

I'm back!! and the bike still will not start on normal fuel.
I've injected lighter fuel into the bores and it fires up normally for
a second or two. To my mind this eliminates ignition and mechanical
malfunction.
Since I can drain the carb bowls, I know I have fuel to the carbs. I've
stripped and cleaned them and found one blocked starter (choke) jet.
I've blown through all the galleries of both carbs. I've removed the
air filters temporarily.
Now I'm stuck - what can it be? there's nothing else left to check, is
there?

 

A month ago, you were saying that you would try to start the engine and
you'd immediately foul the spark plugs, apparently with gasoline. You
said that the engine acted like it had far too much compression and it
would hardly turn over if you pushed it...

This suggests to me that you had a stuck float valve and that the
combustion chamber of at least one cylinder might have filled up with
gasoline. Does the oil smell like gasoline? Did it ever smell like
gasoline? Did the oil level mysteriously rise? Did you find a bunch of
oil in the air box?

Looking at the carburetor parts fiche and the carburetor assemply fiche
for the EX-305 at www.partsfish.com, I see that the carbs shown have
real choke plates, not the starting enricheners used on other CV
carbs...

The starting drill on a carburetor equipped with a real choke plate is
to close the choke fully and push the starter button with the throttle
fully closed until the engine blubbers a bit like it's going to fire.
On a cold morning, it's a good idea to turn the idle speed knob all the
way down so the throttle butterflies are completely closed. That way
the engine will have the most vacuum to pull fuel up out of the float
bowls. OK, so you push the starter button with the choke fully on and
the throttle fully closed. The engine starts to blubber a bit like it
wants to star. Then you open the choke about 1/3rd and you can use a
little bit of throttle when you push the starter button again. It
should start and you can nurse the throttle with one hand while you
gradually open the choke. Then you can warm the engine up and readjust
the idle speed knob...

If the float valve was stuck and the fuel level was too high, the
engine would tend to flood on full choke, because it's easier to lift
the fuel up a shorter distance out of the float bowl...

The fiche doesn't show any starter jet, it shows the typical pilot jet
and main jet arrangement. It's possible that this carb can only get
starting fuel/air mixture through the idle jets and the idle air
passages.
I see that the idle mixture screw is hidden on the side of the carb,
sealed under an anti-tamper plug. The idle mixture screw is going into
the carb body horizontally and I can't tell if it's an idle AIR screw
or an idle FUEL screw...

Calling it an idle AIR screw means you turn it IN to richen the idle
mixture. Calling it an idle FUEL screw means you turn it OUT to richen
the idle mixture. Actually, it's an idle MIXTURE screw, but we call it
one thing or another depending on whether it's upstream or downstream
of the throttle butterflies...

The parts fiche is cagy. It calls it "screw, pilot adjust"...

I've explained many time how to drill out the EPA anti-tamper plugs so
you can clean out the hole that the idle mixture screw goes into...

You can google that up if you look for "kaybearjr@aol +EPA"...

Apparently, your carbs get their idle air from an airjet that's
underneath the rubber diaphragm on top of the carb. Gawd only knows
what happens to idle air if there's a tear in one of the diaphragms :-(

Here's a list of parts from the carburetor parts fiche that affect carb
tuning and what they do:

13091 HOLDER,NEEDLE JET---The orifice hole size affects mixture more
than the tapered needle from 1/8th to about 3/8ths throttle opening;
the air emulsion holes can get plugged up, making the fuel droplets
coming out of the needle jet too large for the engine to burn easily...

16007 COLLAR slide valve spring seat
16009A NEEDLE-JET,#N051---Sometimes newbie's assembly the collar and
the needle in the wrong order, the tapered needle is too high in the
needle jet, and mid-range mixture is too rich...

16014 SCREW,PILOT ADJUST---(Those cagy mugwumps won't take a stand on
what it does!)

16017A JET-NEEDLE,#6 ---Tapered needle affects mixture from 1/4
throttle to 3/4 throttle as it is pulled out of the needle jet hole by
the vacuum slide...

16030 FLOAT VALVE--It might just be be stuck. Spray some aerosol carb
cleaner on it to free it up...

16031 FLOAT--It might leak or be set wrong, and the fuel level might be
too high...

16126 VALVE,VACUUM... The vacuum slide controls vacuum in the carb's
venturi; it might be gummed up and stuck, might have hole in rubber
diaphragm...

92009 SCREW,PLUG---Dunno what this is for; maybe this plug is for
cleaning out idle and starter air passages?

92022 WASHER,PLAIN---A very small washer that goes onto pilot adjusting
screw....

92055 O RING,PILOT ADJ---A tiny critical o-ring that is sometimes lost
down in the hole during cleaning or falls onto the bench and isn't
noticed...

92063 MAIN JET,2ND,#95---It affects mixture at 3/4 to full open
throttle. I have seen main jets fall out of the needle jet holder into
the float bowl and the engine ran just fine until I tried to use full
throttle, then it drowned in gasoline...

92064 PILOT JET,#35-- It affects mixture from idle to full throttle,
with less and less effect as throttle opens; on larger displacement
motorcycles, this jet is supplying most of the fuel that the engine
needs for cruising down the highway at only 1/8th to 1/4 throttle...

92066 PLUG,PILOT SCREW--- This is the EPA anti-tamper plug that we
tuners drill out so we can tamper with the idle mixture to our heart's
delight...

92081 SPRING, PILOT ADJ SCRW---It goes onto the pilot air screw first,
then the washer, then the o-ring, in that exact order, no other...

 

Hi Krusty,
I think you have put your finger on a point that has been staring me in
the face for ages.
a) The oil level sight glass is full - I thought this was because of
the angle the bike is sitting at.
b) A slowly expanding stain of fluid below the bike - I thought this
was because of the fuel I had dumped from the float bowls and I was
only mildly curious about the oily texture of it.

So, because I have been leaving the fuel on, I am now confident that I
have a crankcase full of oil and gas which has probably drained through
the breather pipe.
After cleaning the carbs, I think the flooding has stopped, but trying
to fire it up with a crankcase full of gas might not only be difficult,
but thoroughly dangerous.
Also, when I stripped the carbs down, there should have been a very
small spring attaching the float to the needle. This was missing on one
carb. I am fairly sure that this spring is to ensure that the needle
drops when the float drops - so is not the cause of this problem.
I'll get on to this tonight and hope to have some good news later.
Thanks

 

If your Kawasaki has the typical vacuum operated petcock, you're
relying on a spring to automatically close a valve in the back of the
petcock every time you shut the engine off...

If you're like a lot of riders, you may think that the RESERVE part of
the
fuel tanks is just a handy bit of extra fuel so you don't have to
remember to fill up, you just ride until the engine runs out of gas,
switch to RES and go find gas and fill up...

This is a practice which will lead to dirty carburetors and a dirty
petcock that won't shut off automatically. The normal standpipe that
the petcock draws fuel from is about 3 inches long and that is usually
above the level of any rust or water that may have accumulated in the
tank...

But, if you use the RES setting on the petcock regularly, you are
draining all the water and rust from the bottom of the tank right into
the carburetors. An auxilliary fuel filter would catch the rust, but
the water could flow through into the carbs, and the automatic fuel
shutoff valve inside the petcock might get fouled with rust and dirt
and your crankcase might fill up with gasoline...

I have a handy little clamping surgical hemostat that I use to clamp
off the fuel line if my pet cock doesn't shut off automatically...