Bike works fine, then won't start

[Nate91kat]

This is kind of a long read, thanks. My bike was running a little crappy-I knew the carbs were dirty because I'd never cleaned them and owened the bike for 2 years and I seriously doubted the guy before me ever cleaned them. When I got in there, they were really dirty-wondered how the bike ever ran.
I cleaned the carbs, put them back in-bike ran great for about a week. Decided to drive up the canyon with my buddy. Got half way up the canyon and stopped to chat for a while. When I went to start it back up, it took a few trys to start-it would run for a second below 2000 rpm's then die. So once it started I gave it lots of throttle and we continued up the canyon. We got to the top-(about 8000 feet in elevation) and stopped. Walked around for about 5 minutes. Bike wouldn't start at all. I tried for about 10 minutes-then had my friend give me a push to where the RPMs would be above 2000. We got the bike started and rode home.
The next morning-it took a few tries but the bike started and ran fine for about a week, but every now and then it would kinda choke up (not really sure how to describe that). So I changed my plugs. All the plugs were black-so i think it might be running rich. The next day I rode the bike to work, after work I was riding home-after about 2 minutes I came to a stop light and idled for about 10 seconds, then it died and I couldn't get it to start back up. After about 30 minutes in 98 degree weather and full gear-my friend showed up and we push started the bike again. I never let it get below 4000 RPMs till I got home, once there it died as soon as I let it get down to idle.
I haven't tried to start it today, I'm looking for possible causes. When I cleaned the carbs I checked all the O-rings-they all looked good, I checked all the float heights-one was a little high so I adjusted it. I didn't syncy the carbs though after putting them back on the bike. Could my problem be a carb sync issue or something else? Any ideas or feed back would be great.

Thanks

FYI: Bike specs: 91 katana 600, about 30,000 miles-K&N air filter, Stage 1 jet Kit, Yosh exhaust.

[Mojoe]

carb synch could be it if it is off enough, but it should still start. synching the carbs is basically just all carbs opening/opening closing the same amount in unison.
Seeing as your bike won't start at all, I am doubting that is the problem.
Your profile says the bike is a 91. If that is the case, I would suggest looking at the plug wires. I just had a similar problem as you and it resulted in the bike not starting at all. It was a bad plug wire. One was really bad, and another not so good.
If you have an ohms meter and know how to use it, check the resistance on the wires. Do the coils too.

[Nate91kat]

Thanks for the responce. I was under the impressions that the coils and wires where one piece? (that's what I've heard of most sport bikes) Can you remove the wire from the coild and just replace that? If so, does anyone know right off the top of their head the resistance for the wire?

Thanks

[loudnlow7484]

check your choke, make sure it is functioning correctly and the linkage is all good. kinda sounds like it's sticking on.

[Nate91kat]

I'll check the choke cable to, thanks

[Nate91kat]

Follow up: tried to start the bike this morning and would not start. I checked the choke cabe, it was not sticking-it was working fine. I pulled the coil that has #2 and #3 wires. #2's cap almost popped right off-felt like it wasn't connected to the wire very well.
I tested the coil and wires, seemed to be ok-wire #2 was showing a slightly lower resistance than #3.
I reassambled the unit, making sure that #2s cap was on right. Started up on the first try. I'm guess most the problem was coming from #2 plug not making a good connection.