Electrical or carbs?

Hi all. I am trying to start my project Z750/1105. Its an 84 Kz750 frame
with an 82 KZ1000M engine. I have installed a new out of the box Boyer
electronic ignition. Its wired up as per their instructions. When tested
individually each plug lead is firing. All plugs are good. Carbs are getting
fuel, lots of compression. the most I can get is a near start with an
occasional backfire through the left side exhaust (4-2's). The bizarre thing
is the pipe on 1&2 is getting warm while trying to start but 3&4 pipe is
remaining cold. I have tried swapping carbs with no luck. Can anyone tell me
how I can test the electronics and timing without actually being able to
start the bike? At first glance it would appear that only 1 plug per coil is
firing, i.e. firing plug 1 on the left coil and plug 2 on the right coil.
Anyone ever experienced this or have any idea if its possible? I've wired
the coils as per the Boyer instructions, common power 12V to positive on the
left and right coils, and the green from the ignition module to the negative
on the right coil, black from the ignition module to the negative terminal
on the left coil. Are the plug leads from the coil position specific, i.e.
does it matter on the rh coil if #1 comes from the top and #4 from the
bottom of the coil or vice versa? The Boyer came with a stator plate and
rotor, I removed all the old components ( stock stator plate points breaker
etc) from the housing, am I an idiot and should have kept something from the
old ignition?? Please HELP!!!!! I'm pulling my hair out trying to figure
this out but have hit a wall.

tia
Tom

 

exhaust (4-2's). The bizarre thing is the pipe on 1&2 is

When the exhaust pipes are cold, I blame the carburetors...

The carbs may be a little out of synch, but you can't synch the carbs
until you get the engine started and warmed up...

Turn your master idle knob all the way counterclockwise so the throttle
slides or butterflies are completely closed. Most CV carbs don't have a
real choke plate, but I understand that some Kawasaki carbs did have
choke plates. But, if you carbs have the little starting enrichener
valve on the side of each carb, they won't suck enough fuel air mixture
past the slides or butterflies to start if the slides or butterflies
are slightly open. There just won't be enough vacuum to suck enough
fuel/air mixture to the cylinders. It gets worse if the idle jets are
plugged up, the engine also needs fuel from the idle jets to start. So,
turn the master idle knob all the way counterclockwise, and try to
start the engine without twisting the throttle grip...

If the engine starts, you can keep it running by holding the throttle
until the engine warms up, then reset your master idle knob so the
engine idles at the correct speed...

Then you can try synching the carbs...

 

Thanks thus far Krusty! The carbs I originally tried on the engine were
Mikuni smoothbores, here's a link to the exact set
http://cgi.ebay.ca/ws/eBayISAPI.dll?ViewItem&item=4512521960

they are totally foreign to me, any tips as to areas of concern to look at
when I take them apart for cleaning? I've cleaned my cv's many times, but
have never had any experience with carbs like these.

Something I should also have mentioned. While trying to start it the second
time, with the old cv's on it, I actually choked the # 4 carb with my hand
and while I ended up with a wet hand, the plug was still relatively dry and
clean in that cylinder?!?

Tia
Tom

 

This may sound silly, but do you have the plug wires in the right firing
order ? Was it running before you did any of the work?

Good Luck...

Fwed

 

messenger1 wrote:

They aren't VM29 or VM33 smoothbores at all. Those two smoothbore carbs
had round slides and they were popular conversion carbs in the early to
mid-1980's. I can tell that they aren't smoothbores by looking at that
black choke knob, which you have to pull to the left to apply the
"choke". VM29 and VM33 smoothbores had a lever that you lifted up to
apply the "choke". Maybe those are just the stock carbs
from an early Kawasaki I-4?

They probably don't have EPA plugs concealing the idle mixture screws,
so you should be able to remove the idle mixture screws easily, they
are on the sides of the carbs, 2 on the left side of 1 and 2 carbs, 2
on the right side of 3 and 4 carbs...

That type of idle mixture screw adjusts the idle *air* on slide valve
carbs, so turning the screw clockwise decreases the amount of air to
the idle fuel/air mixture, making it richer. That's the opposite of
what a CV carb's idle mixture screws do...

To synch the carbs, the black covers have to be removed and there's a
screw under the covers that raises and lowers the slides...

If the carbs are off the engine, you can do a "bench synch" by turning
the master idle knob clockwise many turns so the slides come up off the
bottom of the venturi and then lay 4 rods of the same diameter under
the slides. If you happen to have 4 drills about 1/8th inch in diameter
that works good....

Then you can turn the master idle knob back the other way until the
first slide just touches one of the rods. Then you can adjust those
screws under the caps so the other three slides all just touch the rods
at the same time...

Then the master idle knob can be unscrewed all the way and when you
start the engine, you'll have to hold the throotle open until the bike
warms up enough so you can adjust the master idle knob to the specified
idle speed...

I've experienced the same thing, hand choking an engine that's
reluctant to start. It makes the engine suck gasoline up past the
needle jet/jet needle orifice, instead of pulling gasoline through the
idle jets and starter valve, which is what you want to do...

And, engines can't burn great big drops of raw gas, they like to have
the gasoline well-atomized, into the finest mist possible, for
good burning...

That's why idle jets and needle jets are cross-drilled for fuel/air
emulsification...

If you ever got any water into your gas tank, and it found its way down
into your float bowls and got sucked up into the carbs, the water could
have combined with the alcohol that's added to gasoline.
Then that stuff turns into calcium carbonate and blocks the tiny holes
in your idle jets and blocks the emulsion holes and it all has to be
cleaned out by very gently poking a fine needle through the holes...

The needle jet can usually be pushed up or down to get it out of the
carburetor body, it's just a light push fit. The idle jets are a
special problem, you should never attempt to remove an idle jet unless
you have a small slot screwdriver that fits the jet perfectly.
You need to push hard against the idle jet to keep from slipping out of
the slot and buggering the jet...

Also, how are the valve clearances? Are both intake and exhaust valves
closing fully and sealing the combustion chamber?

 

I have mixed up the spark plug leads a few times. The engine will
usually resist starting, but often starts on one or two cylinders...

On an I-4 with 2 dual lead coils, one coil, usually the left hand coil,
fires cylinders #1 and #4, the other fires cylinders #2 and #3 at the
same moment, producing a "waste" spark on the exhaust stroke of one of
the pair...

When adding an aftermarket ignition system, the mechanic does need to
pay attention to where the spark plug leads go, as well as paying
attention as to which pickup coil or set of points goes to which coil...

 

I'm copying all this down for future reference! Valve clearances are within
specs, the engine has about 500km since a head job by the previous owner (a
mechanic fwiw). I've cleaned the carbs as best I can, they were very clean
no deposits all orifices clear, ran a fine wire through them anyhow, blew
out all available passages with compressed air etc. I now noticed when
checking the plugs for the 400th time, they will arc up to 1/2" when held
ungrounded, but will not arc when the plug is grounded (i.e. installed) ???
any ideas on this ?

tia!
tom

 

doh!

Boy do I feel dumb, I went and bought 4 new plugs just for the hell of
it....and guess what....damn thing sparked right up as though it had been
ridden all day instead of not been started in a year! Overthinking is the
death of me, I could not wrap my feeble brain around the possibility of
something as simple as the plugs!

thanks all for the invaluable advice and input, anything I've learned here
is a bonus for me

regards
Tom
(biggest assed grin I've had in a long time, darn thing sounds like a top
fueler)

 

Heh. I had that happen with a little Z200 single last year. I'd fitted
brand new plugs (and points....) and all of a sudden it died.

"It can't be the plug; it's new."

Oh yes it was....

 

when the plug is grounded (i.e. installed) ???

It means that you have about 15KV to 20KV at the plugs but the voltage
rise time is too slow to overcome the voltage leakage across the
insulator, so the voltage gets used up before a spark can occur.
Holding the whole spark plug away from the cylinder head prevents the
voltage leak...

Once upon a time, "voltage boosters" were made for spark plugs. All
they were was an external spark plug gap that fit on the outside of the
spark plug so the voltage would have to build up high enough to jump
the bigger external gap before jumping the smaller gap on the spark
plug. The "voltage boosters" were designed to overcome voltage loss in
engines that burned a lot of oil...

Look deep into the spark plugs with a magnifying light that is made for
inspecting spark plugs. If you don't see a very black ring inside the
plug, then the plugs have been overheated and the insulation has broken
down inside. The voltage leak may be internal, instead of across the
insulator nose...

I have seen this happen, too, especially on the old-style Champion
plugs with steel cores. NGK and ND plugs have used copper cores for
years, the copper is more temperature stable, so the copper core plugs
can withstand more heat cycles...

 

thanks all for more invaluable info! as usual this forum proves to be an
invaluable resource for any mc related technical questions.

Tom