Hard Starting KZ1000

Greetings all. I have a 1982 KZ1000 engine, with Wiseco 1105 bigbore and a
set of GSXR flat slides and 4-2 pipes. This engine is absolutely the most
cold blooded thing I have known since my sister in law. When trying to start
it over the weekend, it popped and kicked for about 2 minutes before
sputtering to life. I didn't run it very long as it sounded like a v-twin
and was emitting nasty fumes.As I was starting it, I noticed 1 of the head
pipes (no2) was actually glowing red hot. Pulled the plugs and they looked
ok albeit a bit sooty. I have a Boysen electronic ignition installed and may
have misinterpreted the timing advance instructions. What would cause 1 pipe
to get far far hotter than the rest? carbs? ignition?

TIA!
Tom B

 

Is that a completely different set of carbs from the smoothbores that
you were talking about before, the ones that didn't seem to be VM29's
or VM33's?

Do those "GSXR flat slides" have accelerator pumps? You wouldn't want
to twist the throttle grip and squirt a bunch of excess gas into the
cylinders on start up, you'd want to use the "choke" correctly...

You said that you were going to save all the information I gave you
last time. It's still available, Google.com has archived everything
I've said about carbs over the last few years.

Does your wife know you've been hitting on her sister? Do you think she
won't find out? ;-)

Initially, the fuel/air mixture is too lean for starting because your
carbs are dirty, the idle mixture screws are set wrong, or you just
don't undertand how to use what passes for a "choke" on Japanese
carburetors. DO NOT twist the throttle when you push the starter
button...

If you will google up "kaybearjr@aol +choke" you can read what I've
explained about chokes on Japanese motorcycles. I've explained it at
least 100 times. They don't HAVE a choke, a whole different strategy is
required to start an engine without a choke...

Lean starting mixture. but at least it started...

Engine was running on 2 cylinders, and your old alcohol-containing
gasoline broke down into nasty-smelling aldehydes. Etymology: German
Aldehyd, from New Latin al. dehyd., abbreviation of alcohol
dehydrogenatum dehydrogenated alcohol
Date: circa 1846
: ACETALDEHYDE; broadly : any of various highly reactive compounds
typified by acetaldehyde and characterized by the group CHO
: a colorless volatile water-soluble liquid aldehyde C2H4O used chiefly
in organic synthesis
Acetic acid is what makes vinegar smell the way it does. Aldehydes and
vinegar smell bad and make your nose and eyes water. Don't run your
engine in the garage and breathe the fumes.

Rich mixture. Maybe from flooding the engine because you didn't
understand how the "choke" works, and you twisted the throttle grip, or
maybe the previous owner of the carbs set the idle mixture screw richer
on #2 cylinder or maybe the float level is too high, or the float valve
is stuck...

misinterpreted the timing advance instructions.

If you set the timing too far advanced, the starter would have to
struggle against preignition. If you set the timing retarded, the
starter would have a much easier job...

Rich mixture. The ignition would work the same way on all four
cylinders.
Modern electronic ignition systems are very reliable. They either work
right or they don't work at all. Motorcycle carburetors are
misunderstood by riders. This misunderstanding causes most starting
problems. Clean your carbs, adjust them correctly, use the "choke"
correctly, and keep your carbs clean and they won't give you a lot of
problems. And, keep your battery charged up so you won't have
electrical problems aggravating your misunderstanding of your
carburetors...

 

same ones, poor description on my part! They are apparently early GSXR
smoothbores WITH accelerator pumps

saved and read and re-read countless times thank you ! I have cleaned them
once and bench synced them as per your reccomendations, not much difference
though, maybe another cleaning ?

shes a hottie so its worth the risk

have never used the throttle when starting except when it was popping and
kicking like it just needed a little push to start.

I've read and reread all I can find on that topic, but I'm still dumb as a
brick, what exactly does the "choke" accomplish then?

ok, carbs need another cleaning I'll assume?

brand new gas fresh from the station, tank is spotlessly clean and have an
inline filter attached

ok will try again without throttle or choke when it gets a bit warmer, just
to discount my sisinlaw theory

now and then while trying to start it, it seems to hesitate like theres a
huge load of compression to overcome, I'll re-read the timing instructions.

thanks again krusty, I'll pull them off again, try re-cleaning and see what
happens. Incidentally I have a vacuum operated petcock installed because I
don't have enough clearance between the tank bottom and top of the engine
for a Pingel. I had to make a vacuum port out of a drilled screw, installed
in one of the test ports on the carbs, could robbing this minute bit of
vacuum from the carbs be part of my probs?

regards & TIA
Tom

 

The idle jets are have really tiny holes in them, the orifices are only
0.012 to 0.016 imches in diameter, but if you remove them carefully
with a slot screwdriver that fits the slot perfectly, you can clean the
orifices out and clean out the cross-drilled emulsion holes too. If you
follow the procedures I outlined for removing the EPA anti-tamper plugs
and counting the turns it takes to screw the idle mixture screws all
the way IN and then remove the screws, you can squirt Berryman's B-12
Chemtool aerosol carb cleaner through the passages. You can squirt B-12
into the idle mixture screw holes and it should come out the pilot air
intake hole in the carburetor bell mouth, it should come out the hole
the idle jet screws into and it should come out through the three idle
mixture ports in the carbutetor throat downstream of the throttle
butterfly. You can squirt B-12 in the hole where the idle jet goes
while holding your finger over the pilot air intake hole and it should
come out the three mixture ports and the
hole where the mixture screws go. If you use up a whole can of B-12
douching out your carb, it's less than $3, money well spent...

The "choke" is a seperate tiny carburetor built into side of each main
carburetor. There is a tiny valve in a *air* passage that bypasses the
main bore of each carburetor. When you move the "choke" lever to the
full "ON" position, the tiny valve is opened, and vacuum from the
engine downstream of the throttle butterfly sucks fuel and air through
the bypass port. This
"choke" system also needs the help of fuel air mixture coming from the
idle jets to work just right...

If you twist your throttle grip while you're cranking the engine over
with the starter, there isn't enough vacuum to suck fuel air mixture
through the bypass hole. If you twist the throttle a few times, you
will squirt a lot of gas from the accelerator pumps into the carbs and
flood the engine.

If the exhaust still stank really bad when you started the engine, it
was running much too rich, kicking out hydrocarbons and carbon
monoxide, and some of the fuel molecules broke down into the stinky
stuff called "aldehydes".

(Exhaust emissions from rich mixtures and incomplete combustion are
what led to all the pollution control equipment that modern motorcycles
are being afflicted with. Honda is a world leader in engine
development. They wondered if something couldn't be done with the
broken down molecules of fuel that normally got kicked out the exhaust
pipe. They built a special 400cc single cylinder two-stroke engine with
an exhaust throttling valve that trapped exhaust gasses for long enough
to allow the broken down fuel molecules to *recombine* into a burnable
mixture. Honda won the Dakar Rally with that "advanced recombinant
technology" motorbike. It got 40 mpg, compared to the 15 or 20 mpg a
regular 2-stroke would have gotten.)

warmer,

No, you need to apply the so-called "choke", just don't twist the
throttle grip at all. And, to make the tiny carb in the bypass port
work right, turn your master idle knob all the way counterclockwise so
the throttle butterflies are completely closed. The master idle knob
will be underneath or on top of the carbs.

With the throttle butterflies completely closed, you will have enough
vacuum to suck fuel out of the float bowls, through the bypass, and out
the idle mixture ports. When the engine fires up, you will have to very
carefully operate the throttle to avoid squirting a bunch of excess
gasoline into the cold engine and flooding it. You can adjust the
master idle knob to the right idle speed when the engine warms up.>

Somebody asked that question to one of the technical columns at one of
the motorcycle magazines. The answer was that the amount of vacuum
required to open the petcock was so small it wouldn't affect anything.
I think the wiriter's original question expressed concerned that the
vacuum was affecting carb syncronization. Anyway, that vacuum just
opens the petcock up and then there is no further air flow through that
line. If you still think the petcock's vacuum requirement affects your
engine's starting or running, you can always turn the petcock to PRI...

 

I'm not an expert here, but I recall reading a post on a web forum about
someone installing later model carbs on a KZ. He determined that the KZ
with its more upright cylinder configuration was keeping the carbs from
being level since they were designed to be used with a more inclined
cylinder head. He custom built some intake adaptors so the carbs would be
level. If this is your situation, I hope it helps.

Otherwise, the popping and banging and red-hot pipe would seem to indicate
and out-of-time engine.

HTH,

- Nate >>

 

hmm... I never even thought about carb positioning as I thought since a
bike is rarely level unless stopped the positioning would not matter? I
installed this engine in a KZ750 frame and it and the carbs are level to
the ground when the bike is upright, but I have no idea of the position the
carbs were in when installed on the original engine they were intended for
(an early model GSXR.) I've cleaned the carbs twice as per Mr. Krusty's
directions and advice, but have never been able to decipher the handwritten
timing instructions that came with the Boysen ignition. I just set the
timing to where it would run, started it and adjusted it till it ran at what
"sounds" like a decent timing advance. My timing adjustment consisted of
starting the bike, getting it warm enough to idle and then rotating the
adjuster till it would rev smoothly without pinging. I guess I should try
contacting Boysen for a detailed installation sheet with proper timing
instructions. I bought this one off eBay and the original instructions were
not included but the seller had drawn up his own diagram and instructions.

thanks again all for the invaluable input and advice!

Tom B