Posted by Messenger on August 12, 2007, 8:13 am
Greetings all!
My friend has an 87 Kawasaki ZL1000. This bike has Mikuni CV carbs on it.
Recently, for no apparent reason, the number 2 cylinder began to spew
enormous amounts of raw fuel, enough to kill the plug. We pulled the carbs
and cleaned them but that didn't help as its still spewing fuel out the
overflow tube and into the cyclinders.
An old very wise friend of mine says he believes it to be a diaphragm
issue...although I trust this guy implicitly, I'd like a second opinion as
the diaphragms are an ungodly 100.00USD+ each and carbs for this bike are
scarce as hens teeth.
Second question is, apart from differences in jetting, any Kawy guys out
here know if the carbs from a ZX1000 of that vintage would be the same or
similar?? this is essentially the same engine as my ZX900 or a ZX1000
stuffed into a crusier frame.
TIA!
Tom B
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Posted by Messenger on August 12, 2007, 8:18 am
> Greetings all!
> My friend has an 87 Kawasaki ZL1000. This bike has Mikuni CV carbs on it.
> Recently, for no apparent reason, the number 2 cylinder began to spew
> enormous amounts of raw fuel, enough to kill the plug. We pulled the carbs
> and cleaned them but that didn't help as its still spewing fuel out the
> overflow tube and into the cyclinders.
> An old very wise friend of mine says he believes it to be a diaphragm
> issue...although I trust this guy implicitly, I'd like a second opinion as
> the diaphragms are an ungodly 100.00USD+ each and carbs for this bike are
> scarce as hens teeth.
> Second question is, apart from differences in jetting, any Kawy guys out
> here know if the carbs from a ZX1000 of that vintage would be the same or
> similar?? this is essentially the same engine as my ZX900 or a ZX1000
> stuffed into a crusier frame.
> TIA!
> Tom B
I forgot too mention, a visual inspection oif the diaphragm shows nothing.
When I first pulled the cap of it, it looked a bit wrinkled but otherwise
intact and with no obvious holes or tears.
Tom B
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Posted by Albrecht via MotorcycleKB.com on August 12, 2007, 9:55 am
Messenger wrote:
>My friend has an 87 Kawasaki ZL1000. This bike has Mikuni CV carbs on it.
>Recently, for no apparent reason, the number 2 cylinder began to spew
>enormous amounts of raw fuel, enough to kill the plug. We pulled the carbs
>and cleaned them but that didn't help as its still spewing fuel out the
>overflow tube and into the cyclinders.
The float valve is stuck open. Drain the carbs, pull the fuel hose off and
refill the carbs the the hose with a 50/50 mixture of Berryman B12 Chemtool
Choke and Carburetor Cleaner and let it sit in the carbs for half an hour.
Then start the engine.
If the float valve leakage doesn't stop, you'll have to pull the carbs off
and manually clean the float valves.
If the problem turns out to be a lot of rust and sediment in the gas tank,
you'll have to clean the tank and reseal it with Kreem or POR-15.
http://houseofmotorcycles.bikebandit.com/partsbandit/ShowSchematic.aspx?deptId (8740&machineIdF61
16030: FLOAT VALVE
SEAT PRESSED IN BODY
>An old very wise friend of mine says he believes it to be a diaphragm
>issue...although I trust this guy implicitly, I'd like a second opinion as
>the diaphragms are an ungodly 100.00USD+ each and carbs for this bike are
>scarce as hens teeth.
The symptoms of a torn diaphragm or a diaphragm with a hole in do not include
spark plug fouling or overflowing. Think about it. What does a diaphragm have
to do with regulating fuel level in the float bowl?
If the diaphragm is damaged, the engine will start and idle, but the
mototorcycle will not accelerate when you open the throttle. The torn or hole
diaphragm cannot lift the jet needle out of its hole, so the mixture is too
lean, not too rich.
>Second question is, apart from differences in jetting, any Kawy guys out
>here know if the carbs from a ZX1000 of that vintage would be the same or
>similar?? this is essentially the same engine as my ZX900 or a ZX1000
>stuffed into a crusier frame.
You don't have to be a "Kawy guy" to know that you don't need a different set
of carburetors to fix something as simple as a stuck float valve.
If it turns out that the pressed in valve seat is slightly damaged, you still
don't need a new carburetor, you can refinish the valve seat with a little
emery cloth on the end of a small diameter rod or the dull end of a 1/8th
inch drill.
--
Message posted via MotorcycleKB.com
http://www.motorcyclekb.com/Uwe/Forums.aspx/tech/200708/1
Posted by Messenger on August 12, 2007, 12:09 pm
> Messenger wrote:
>>My friend has an 87 Kawasaki ZL1000. This bike has Mikuni CV carbs on it.
>>Recently, for no apparent reason, the number 2 cylinder began to spew
>>enormous amounts of raw fuel, enough to kill the plug. We pulled the carbs
>>and cleaned them but that didn't help as its still spewing fuel out the
>>overflow tube and into the cyclinders.
> The float valve is stuck open. Drain the carbs, pull the fuel hose off and
> refill the carbs the the hose with a 50/50 mixture of Berryman B12
> Chemtool
> Choke and Carburetor Cleaner and let it sit in the carbs for half an hour.
> Then start the engine.
> If the float valve leakage doesn't stop, you'll have to pull the carbs off
> and manually clean the float valves.
> If the problem turns out to be a lot of rust and sediment in the gas tank,
> you'll have to clean the tank and reseal it with Kreem or POR-15.
>
http://houseofmotorcycles.bikebandit.com/partsbandit/ShowSchematic.aspx?deptId (8740&machineIdF61
> 16030: FLOAT VALVE
> SEAT PRESSED IN BODY
>>An old very wise friend of mine says he believes it to be a diaphragm
>>issue...although I trust this guy implicitly, I'd like a second opinion as
>>the diaphragms are an ungodly 100.00USD+ each and carbs for this bike are
>>scarce as hens teeth.
> The symptoms of a torn diaphragm or a diaphragm with a hole in do not
> include
> spark plug fouling or overflowing. Think about it. What does a diaphragm
> have
> to do with regulating fuel level in the float bowl?
> If the diaphragm is damaged, the engine will start and idle, but the
> mototorcycle will not accelerate when you open the throttle. The torn or
> hole
> diaphragm cannot lift the jet needle out of its hole, so the mixture is
> too
> lean, not too rich.
>>
>>Second question is, apart from differences in jetting, any Kawy guys out
>>here know if the carbs from a ZX1000 of that vintage would be the same or
>>similar?? this is essentially the same engine as my ZX900 or a ZX1000
>>stuffed into a crusier frame.
> You don't have to be a "Kawy guy" to know that you don't need a different
> set
> of carburetors to fix something as simple as a stuck float valve.
> If it turns out that the pressed in valve seat is slightly damaged, you
> still
> don't need a new carburetor, you can refinish the valve seat with a little
> emery cloth on the end of a small diameter rod or the dull end of a 1/8th
> inch drill.
> --
> Message posted via MotorcycleKB.com
> http://www.motorcyclekb.com/Uwe/Forums.aspx/tech/200708/1
Sorry, should have mentioned that the first thing i did was pulled, cleaned
and inspected the float valve, and actually swapped the valve from another
carb in the same rack.
As for diagnosis that the diaphragm might be the culprit....the way it was
explained to me was " if the diaphragm leaks air there is no longer negative
pressure to prevent the fuel from just dumping into the cylinders". That
made sense to meas I can't figure out what else that diaphragm does???
Tom B
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Posted by Rob Kleinschmidt on August 13, 2007, 8:22 pm
> > Messenger wrote:
> >>My friend has an 87 Kawasaki ZL1000. This bike has Mikuni CV carbs on it.
> >>Recently, for no apparent reason, the number 2 cylinder began to spew
> >>enormous amounts of raw fuel, enough to kill the plug. We pulled the carbs
> >>and cleaned them but that didn't help as its still spewing fuel out the
> >>overflow tube and into the cyclinders.
> > The float valve is stuck open. Drain the carbs, pull the fuel hose off and
> > refill the carbs the the hose with a 50/50 mixture of Berryman B12
> > Chemtool
> > Choke and Carburetor Cleaner and let it sit in the carbs for half an hour.
> > Then start the engine.
> > If the float valve leakage doesn't stop, you'll have to pull the carbs off
> > and manually clean the float valves.
> > If the problem turns out to be a lot of rust and sediment in the gas tank,
> > you'll have to clean the tank and reseal it with Kreem or POR-15.
> >http://houseofmotorcycles.bikebandit.com/partsbandit/ShowSchematic.as ...
> > 16030: FLOAT VALVE
> > SEAT PRESSED IN BODY
> >>An old very wise friend of mine says he believes it to be a diaphragm
> >>issue...although I trust this guy implicitly, I'd like a second opinion as
> >>the diaphragms are an ungodly 100.00USD+ each and carbs for this bike are
> >>scarce as hens teeth.
> > The symptoms of a torn diaphragm or a diaphragm with a hole in do not
> > include
> > spark plug fouling or overflowing. Think about it. What does a diaphragm
> > have
> > to do with regulating fuel level in the float bowl?
> > If the diaphragm is damaged, the engine will start and idle, but the
> > mototorcycle will not accelerate when you open the throttle. The torn or
> > hole
> > diaphragm cannot lift the jet needle out of its hole, so the mixture is
> > too
> > lean, not too rich.
> >>Second question is, apart from differences in jetting, any Kawy guys out
> >>here know if the carbs from a ZX1000 of that vintage would be the same or
> >>similar?? this is essentially the same engine as my ZX900 or a ZX1000
> >>stuffed into a crusier frame.
> > You don't have to be a "Kawy guy" to know that you don't need a different
> > set
> > of carburetors to fix something as simple as a stuck float valve.
> > If it turns out that the pressed in valve seat is slightly damaged, you
> > still
> > don't need a new carburetor, you can refinish the valve seat with a little
> > emery cloth on the end of a small diameter rod or the dull end of a 1/8th
> > inch drill.
> > --
> > Message posted via MotorcycleKB.com
> >http://www.motorcyclekb.com/Uwe/Forums.aspx/tech/200708/1
> Sorry, should have mentioned that the first thing i did was pulled, cleaned
> and inspected the float valve, and actually swapped the valve from another
> carb in the same rack.
> As for diagnosis that the diaphragm might be the culprit....the way it was
> explained to me was " if the diaphragm leaks air there is no longer negative
> pressure to prevent the fuel from just dumping into the cylinders". That
> made sense to meas I can't figure out what else that diaphragm does???
Regardless of what you did, it's still a float problem. You just
didn't
find it. As other posters suggested, perhaps you missed an O ring,
perhaps you need to resurface the float valve seat or perhaps you
need another float or float needle.
Re "what the diaphragm does", it provides a flexible membrane
around the slide, such that when you open the throttle butterfly,
the engine vacuum will cause the slide to lift, pulling up the
needle and feeding more gas to the engine.
You can view the operation of the CV carb by hooking a vacuum
to the engine side of the carb and partially covering the air filter
side with a hunk of clear plastic. There should be a secondary air
passage at the top of the carb which will activate the center slide.
Leave this passage unobstructed. As you slide the plastic over the
main air passage, you will observe the center slide lifts as the
vacuum pulls it up.
This kind of bench setup is a nice easy way to sync your CV carbs
before actually installing them on the bike. Set them for identical
lift before installing, then just adjust the idle screws by identical
turns to raise or lower the idle. Also a good sanity check to convince
yourself the carbs are OK when chasing odd engine problems.
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> My friend has an 87 Kawasaki ZL1000. This bike has Mikuni CV carbs on it.
> Recently, for no apparent reason, the number 2 cylinder began to spew
> enormous amounts of raw fuel, enough to kill the plug. We pulled the carbs
> and cleaned them but that didn't help as its still spewing fuel out the
> overflow tube and into the cyclinders.
> An old very wise friend of mine says he believes it to be a diaphragm
> issue...although I trust this guy implicitly, I'd like a second opinion as
> the diaphragms are an ungodly 100.00USD+ each and carbs for this bike are
> scarce as hens teeth.
> Second question is, apart from differences in jetting, any Kawy guys out
> here know if the carbs from a ZX1000 of that vintage would be the same or
> similar?? this is essentially the same engine as my ZX900 or a ZX1000
> stuffed into a crusier frame.
> TIA!
> Tom B