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Sparkhole spitting fuel

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17 Apr 2021 22:01 #846962 by MartyZ1000
Sparkhole spitting fuel was created by MartyZ1000
Welcome to Carb Twilight Zone, episode 845...

So I have fuel lock or near lock on cylinder #1 when bike´s been standing, KZ1000J3 with Mikuni BS34s,
the thread is helicoiled and not 100% so will have to redo that. But there is fuel visibly spitting out in between
plug and thread at the first starter turns, so regardless of thread there has to be fuel leaking in through inlet when bike stands still.

I´ve changed all the seat gaskets and needles in the floats, float levels look good
so my question is: is there anything else on the BS34 that could cause a leak when bike
is turned off?

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18 Apr 2021 06:02 #846967 by rstnick
Replied by rstnick on topic Sparkhole spitting fuel
On my kz650 and my ZRX I have installed manual petcocks/fuel valves.

This way everytime I park for hours, I turn the gas off.
No gas flows.
Neither sets of carbs on my bikes have overflow tubes.
This is why I use a manual petcock.

There must be an issue with carb #1 not closing off the fuel supply.
​​​​​​

Rob
CANADA

Need a key for your Kawasaki? PM me

1978 KZ650 C2, 130K kms, Delkevic ex, EI, CVK32, PMC easy clutch, ATK fork brace, steering damper, braced swingarm, ZRX shocks, 18" Z1R front wheel.
2000 ZRX1100
2011 Ninja 250R - Wife's
2005 z750s (aka GPz750)
1978 KZ1000 project

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  • Nessism
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18 Apr 2021 09:10 - 18 Apr 2021 09:12 #846984 by Nessism
Replied by Nessism on topic Sparkhole spitting fuel
The petcock should turn off fuel flow when the engine is off, just as long as the lever is set to either "ON" or "RES".  If gas is flowing with the engine off the petcock has failed.  Further, if fuel backflows down the vacuum line port to the carbs the petcock has failed as well.  The petcock "PRIME" feature allows fuel to flow at all times so make sure the lever is not set to that setting.  Prime is designed to fill the float bowls after a long time of inactivity.  Set to Prime, fill the float bowls, then switch lever back to ON/RES from thereafter.
Last edit: 18 Apr 2021 09:12 by Nessism.

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  • DOHC
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18 Apr 2021 11:39 #846991 by DOHC
Replied by DOHC on topic Sparkhole spitting fuel
Also note that if you have collected enough fuel to spray out of the plug threads, you have also probably collected a fair amount of fuel in your oil/sump.  Sounds like it's time to change your oil.

My zrx1100 carbs also do not have a drain tube, so when they overflow fuel pours into the engine.  Yes, this has happened to me.  I think I had about 2 gallons of fuel mixed in with the oil.

'78 Z1-R in blue , '78 Z1-R in black, '78 Z1-R in pieces
My dad's '74 Z1
'00 ZRX1100

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18 Apr 2021 14:33 #846995 by F64
Replied by F64 on topic Sparkhole spitting fuel
Did you use oem float valves?
Aftermarket valves have issues with sealing.

81-KZ440-D2.
Louis Dudzik's GM HEI ignitor conversion installed 2015 s3.amazonaws.com/gpzweb/Ignition/GPZgmHEImod.html
Motogadget m-unit blue installed 2017.
LIC, NY

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19 Apr 2021 20:36 #847068 by MartyZ1000
Replied by MartyZ1000 on topic Sparkhole spitting fuel
Thanks for all the feedback guys, I´m aware of how the petcock works, and I could use any carb´s vacuum port right?
had it hooked up to #2 at first but changed to #1 the last half year. Both Run and Res respond ok with vacuum turning
them on/off.

The carbs are in pretty good shape, I inspected the floats again yesterday (new needles and seats recently) and float
height looks good too. The floats themself are fine. 

I emptied out the oil yesterday and it reeked of gas so will put some new oil in, put the carbs back on and give it another
try.

I also have pods on with bigger mains and run at three turns out on pilot now, but just ordered som new podfs
since the ones I´ve had on are old and done. 

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19 Apr 2021 21:57 #847072 by scubaanders
Replied by scubaanders on topic Sparkhole spitting fuel
Check your PM Marty.

/Anders

Gpz750R1 1982
Gpz750A1 1983
Gpz1100A2 1984
FZ750 1985
Gpz900R -91

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21 Apr 2021 08:52 #847149 by Kaylinator
Replied by Kaylinator on topic Sparkhole spitting fuel
Suck on the vacuum line connected to your petcock. If you swallow fuel, the problem is your petcock. 

1978 KZ1000-A2
kzrider.com/forum/11-projects/613296-1978-kz1000-a2-barn-find

1978 KZ400-B1

2022 Z900RS SE

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21 Apr 2021 11:52 #847165 by Mikaw
Replied by Mikaw on topic Sparkhole spitting fuel

Suck on the vacuum line connected to your petcock. If you swallow fuel, the problem is your petcock. 
Thanks for the laugh captain obvious 

1976 KZ 900 A4 kzrider.com/forum/11-projects/613548-1976-kz-900-a4
1976 KZ 900 B1 LTD
1978 KZ 1000 B2 LTD
1980 KZ 750 E1
Kowledge Speaks, But Wisdom Listens.
Jimi Hendrix.

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21 Apr 2021 13:41 #847170 by MartyZ1000
Replied by MartyZ1000 on topic Sparkhole spitting fuel
Now I've both made and drunk some pretty lousy moonshine in my days but I'd never stoop that low. Not even for a petcock.

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21 Apr 2021 16:58 #847191 by Kaylinator
Replied by Kaylinator on topic Sparkhole spitting fuel
Haha. I mean, I suppose you could put a vacuum pump on it to check, but I guess the farmer in me just takes the easy route. A little fuel never killed anybody. 

1978 KZ1000-A2
kzrider.com/forum/11-projects/613296-1978-kz1000-a2-barn-find

1978 KZ400-B1

2022 Z900RS SE

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21 Apr 2021 22:10 #847211 by MartyZ1000
Replied by MartyZ1000 on topic Sparkhole spitting fuel

Haha. I mean, I suppose you could put a vacuum pump on it to check, but I guess the farmer in me just takes the easy route. A little fuel never killed anybody. 
True! :)
And I did it just that way when I checked it a couple of months ago, the vacuum function seems good. Now I got a good phone
support crash course in swedish from Andlun who set me up for a more thorough check. First off to check that the tank is clean and
rust free, including an elaborate 4 step to do list if it´s not, how to really fix it. Then I´ll set the tank and carbs up to properly check 
both fuel levels with the clear tube test  and that none of them are leaking.

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