Sparkhole spitting fuel

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?

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.
​​​​​​

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.

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.

Did you use oem float valves?
Aftermarket valves have issues with sealing.

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. 

Check your PM Marty.

/Anders

Suck on the vacuum line connected to your petcock. If you swallow fuel, the problem is your petcock. 

wrote:

Suck on the vacuum line connected to your petcock. If you swallow fuel, the problem is your petcock. 

Thanks for the laugh captain obvious 

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.

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. 

wrote:

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.