kz1000J3, Carb #1 By Side Stand, Cly #1 Not Firing

Hi,
I don't profess to be an expert on carbs. I seem to be back to an old problem with cylinder #1 not firing on start up after the bike sits for a few days. The carbs were opened up and inspected last summer to address the same issue; that being the float bowl levels were set too high. They were adjusted and this corrected the issue until recently.

After a few blocks of riding the cylinder engages and the bike then runs like a top. I noticed a few weeks ago, out of carb #1 on start up, some gas spat out of the overflow. I had never in my 18 years of having the bike seen this before. On another occasion after attempting to start the bike, I checked the plug, and it was wet with gas . This I gather could be a carb problem (float level, etc.) and or could it be a petcock leak (it is a vacuum type) causing the bowl to over fill?

I drained the bowl yesterday thinking if it refilled it was the petcock leaking gas into the carb (Btw, the gas was clean). Today I attempted to drain it again and it was emptying gas as if it was full? The plug on #1 was dry. With the bowl filling up again, does this mean my petcock is leaking or something within the carb (a jet) and is leaking gas down to the bowl? BTW the carbs and petcock were rebuilt three years ago with OEM kits. Also, the ignition system from the plugs to battery are OE new. Valves were recently adjusted. The gas is about 60 days old and I don't ride the bike much. I honestly think if I road a few times a week I would not even notice I had an issue.

Any insight would be helpful. Suggestions on looking at the simplest things first to the less simple would be appreciated.

Thanks,

Bad sparkplug cap or wire is the problem.

It's easy enough to tell if the petcock is leaking... just unplug the fuel line. If it pours gas everywhere, then it's leaking.

Are you getting gas in the airbox or cylinders after sitting? If so then it sounds like you need to pull the carbs and clean the float needles, seats and probably replace the o-rings too. You may find that the needles are too worn and need to be replaced. A q-tip with some brasso or mothers on it stuck in a drill is great for polishing the seats (obviously not while they're still in the carbs).

If there's no sign of gas leaking, and there's a bit of white smoke involved, then you probably have leaking valve seals, which are causing your plugs to foul with oil.

Check your #1 plug wire at the coil and the cap.
Steve

For an empty carb to over fill while the engine is not running, two things have to fail - the fuel inlet valve in the carburetor AND the petcock. Are you using a high quality fuel filter? When on the side stand, all the trash will head downhill toward the #1 carburetor. A tiny bit of grit may be preventing the valve from closing fully. Of course this would not matter overnight if the petcock was fully closed.
You may also have an ignition problem, but based on what you describe, a careful cleaning of the petcock and at least one of the fuel valves is in order.

And one or two of these.
Steve

i bet my six pack of beer its just simple . plug wire or cap keep it simple

How would a bad spark plug cable or boot cause an empty carberator bowl to fill up over night?

If your carbs are refilling with petcock shut off or if it's a vacuum type then yes your petcock is likely seeping. You can test this by.. Unhooking fuel line with tap off and see if it seeps or you can do what I do if I have a bad petcock and don't ride bike a few times a week. I use needle nose vise grips and clamp hose shut but not crushing hose. Just put enough pressure to close hose. If your storing bike on side stand the leaking petcock will be really showing on #1 carb since bike is leaning that way. If you replaced needles and seats with aftermarket parts, you likely took the better parts out. Unless they were made by carb manufacturer. Most of the ebay type kits are low quality with float bowl gaskets being only good parts. Problem is not your ignition if bike runs ok after a block or so. I have had a number of bikes do this throughout the years some only a few years old.

Likely a combination of all the above.
Steve

Thanks for the comments. I understand these carbs are linked. Gas is likely migrating over to #1 after I empty bowl. How are carbs linked? I do think the flow valve or float maybe hung up. Put side stand on blocks and tapped bowl with back of screw driver to see if this will free float if hung. Will start in a few days. I gather if valve has dirt in it a good long ride will help remove this so it seats properly?

The carburetors do share a supply circuit, but fuel cannot leap up out of one and travel to another unless you are parking the bike on its side or using some anti-gravity fuel additive.
Riding might dislodge a bit of dirt or rust from the inlet valve, but then you have to wonder where the bit might end up next. All the jets and passageways are much smaller than the inlet valve and are very easily clogged.