1992 Kz1000P Sticky black Goo on spark plugs

I just got finished rebuilding the fuel tap/petcock and disassembling and cleaning the carbs and putting new o-rings in it and setting the floats. I did not do a complete rebuild on the carbs because the needles, seats, etc didn't look bad. Oh and I clean the plugs that have about 1000 miles on them.
Anyway now the bike starts up beautifully. The best it's ever run since I've owned it. BUT after about 10 minutes of run time the tachometer starts jumping around and the idle starts to increase erratically and eventually the bike dies out and won't start until I pull the plugs and clean them. They all have a bunch off black gooey carbon on them, One of the plugs even has gooey chunks on it!
When I had the carbs off I also noticed the intake ports were sticky, I did run some Seafoam through the engine and it cleaned the ports and the combustion chamber up pretty good But the bike is Still having this problem.
I was told by the guy at AtoZone that the plugs are getting too much gas or not completely burning the gas.

Where do I start?

TIA, Kip

hardworkinpd wrote: . . . setting the floats. , , plugs are getting too much gas or not completely burning the gas. . . .

Fuel levels must be within specs as shown by the clear tube test.
If the clear tube test wasn't done, the fuel levels are likely too high, which results in a too rich mixture.
"Float height" is incorrect when producing a too high fuel level.

Good Fortune!

If setting the float levels doesn't work, my bet would be valve guide seals. Might be rings but even with oil getting past the rings my plugs wouldn't foul. With bad seals they would in short order.
Steve

With bad seals they would in short order





Might be a red herring :side: ...electronic tacho needle jumping around can be an ignition coil power supply problem, the tach is triggered by the -ve pulse off either of the coils.

Maybe an ignition related misfire when hot and oil is fouling the plugs? Sticky black goo...oil?

If it's on one side of the plug, It's a valve guide seal.
Steve

If it's on one side of the plug, It's a valve guide seal.





My 16 valve GSX had dodgy oil seals and used to smoke a lot when cold and unused for a few days, but it used to clear it's throat quite quickly once warmed. Kip, are you getting much blue smoke out of the exhaust?

I just did the head but my plugs look like that bottom cylinder after running it for 10-20 minutes.

Adios, Kip

No telling how old the coils are. I just put new spark plugs and new spark plug wires today. Also tried running a 1 up Hotter plug, the bike Hated that!.

Adios, Kip

No blue smoke.

Adios, Kip

Well, I'm beat. worked on the bike All weekend.
Tired, thirsty, smelly, hungry, broke, and neglected a sh!t load of stuff.
And the ole lady's pissed that I'm taking up space in the garage and one of the cars stays out in the driveway!

At least I'm not in jail or the hospital.

I'm going to have a refried bean sandwich and some beers and hopefully a shower if I don't fall asleep (I'm covered in sweat, gas, brake cleaner and exhaust).

Talk to you guys later, Kip

You probably need to adjust the idle mixtures. Cleaning the carbs may have unclogged some of the fuel passages in the idle circuit, causing them to run richer now. I've tried several different ways of doing this myself, totaling around $300 worth of measuring devices and so far the best results have been from the "highest vacuum" method. The process is quite tedious of course, but it is the final step in achieving a perfect idle. After setting the mixtures you'll have to re-sync the carbs (the mixtures affect the vacuum, so if you sync'd the carbs with bad idle mixtures, the carb sync will be off throughout the rest of the throttle range). The process can require several iterations to get right. You need a fairly sensitive and stable vacuum gauge for this. Alternatively you can do the "lean drop" method by ear or with a digital tachometer. It's also tedious, but far less expensive than a good gauge and should produce reasonably good results. You just have to be very careful in counting the number of turns out.

Tuning the idle mixtures won't cure your leaking valve seals, but if you can get it right and you avoid short (< 10 minute) trips, the leaking seals won't foul your plugs.

Checking the fuel height with the clear tube test would at least tell you if any of the float valves are leaking badly.

To quickly and cheaply renew your fouled plugs, hold the electrodes over a blow torch flame until red hot for a while. That'll burn off the hydrocarbons and burn much of the carbon into ash which can be brushed away. Let them cool completely before reinstalling.

Yeah all the idle mixture needle screws were all set at about 2 1/2 turns from bottomed out as per the manual, and that's where I left them.
Can I do the clear tube test with the carbs on the bike?
Also the tachometer needle jumping around once the bike warms up what's up with that?

Adios, Kip