Motorcycle Repair: Failed First Ride, kawasaki ninja zx6, twenty five miles

Question
I purcahsed a used 1993 Kawasaki Ninja ZX6, and took it for my first ride on Sunday.  I had the choke on high when I started it and it started right up the first time.  I gradually let the choke down past halfway and drove for twenty-five miles around the neighborhood.  The ride was fine except that once I got to the high end of second gear just before shifting to third the bike would suddently lunge/thrust and rev until I got it into third.  It ideled fine though and I put it back in the garage until Monday (yesterday) when I took it out to drive it again (my second ride ever on the bike).  I started it again with choke on full and gradually let the choke off after the first minute or so until the tach indicated approximately 1200 to 1500 rpms.  I drove for about two miles, stopped the bike to go into a store, and upon return attempted to start the bike.  However, this time, I needed to give it gas to get it to start and although I got it freom first through third gear, I had to stay on the throttle to keep it from dying.  It finally died while downshifting and I continued to have the same sequence of starting while giving it gas, staying on the throttle through all gears and dying when downshifting to second and at stops.  I had to keep the choke about halfway througout just to make sure it would not die, and finally it lost so much power that I could only get it to go 5mph in first, and then it would die.  The dealership that sold it to me said they put in new spark plugs and gave it an oil change.  It has 10K miles on it.  I am wondering if I might have driving with the choke too high the first time I drove it for twenty miles and maybe flooded the spark plugs and now they are not providing sufficient power, or if there may be antother problem.  I made sure that the gas supply was "on" and not reserve and that I had plenty of gas.  As this is my first bike, and my first ride I am very distraught, and would appreciate any help you could provide.  Thank you.  

Answer
Hi Conner,

Use the choke sparingly when starting. After a couple of minutes, shut choke off completely.

I agree with you. I suspect the plugs were fouled from riding with choke on. Exhaust valves and exhaust pipe were probably glowing orange, too. Bad stuff.

Clean or replace the plugs and try starting again. Advise me what happens.

Respectfully,
Mark Shively