Bike won't start after warmed up.

Hello to all. This should be my last post asking for help, as my bike (1982 kz750e) runs quite fantastic now besides this one quirk: Hard starting if the bike sits after a ride for more then 10 minutes. The issue gets progressively worse the longer you wait after that. In order to get the bike going, I have to completely pin the throttle open for about 5 seconds, once it turns over, I have to blip the throttle to pick up idle speed to normal. I have fuel in the bowls, keihin cv32 carbs , and a spark. The starter turns quickly, not really a voltage issue I don't think. Compression is a bit low, at 120-125 per cylinder, valve have been shimmed to spec. No other issues other then this. Anyone else have experience with this problem? Thanks ahead of time. :silly:

Fuel level in the carbs? Leaking float valve? Having to open the throttle suggests that there is too much fuel.

The fuel level has been adjusted to 4mm from the carb base. Needles are new. I'd say it was an over rich condition but the plugs don't look rich after the incident occurs.

I've also NEVER seen black smoke of any kind.

My pilot settings are currently 3 1/8, 3 1/4, 3 1/2, and 3 turns out. For contrast, my pilot settings when I pulled the factory caps off were: 2 7/8, 2 3/8, 2 3/4, 2 5/8. Is 2 turns out unrealistic on this bike?

Coils?
Steve

I've replaced the coils, thinking that was the end all solution. It still had the same problem, a bit better but not by much. I've since put the original coils back on due to one of my replacements failing in about a months time.

Valves adjusted?
Steve

Hard starting if the bike sits after a ride for more then 10 minutes.

Probably a dumb question on my part but are you using the choke at this point ? I need choke after 10 minutes cool down. Full choke but just for a few seconds.
Everything else looks good except compression.
2 turns out on pilot screws is realistic for bike with airbox and even 4 into 1 exhaust although i had to richen mine a tad recently for a Delkevic exhaust.
I would have suggested fule levels and valves but you have done those.

I do not use the choke at all. Valves have been adjusted as well. Come to think of it, I'm thinking of starting the pilot screws over again at 2 1/4 turns then redoing the vacuum sync to that specific setting. I remember the reason that I didn't like having the pilots that low was off idle performance was crap. But after finding out that my floats we're about 2mm lower thanks to a shitty tape measure, off idle performance is quite great whether at 2.5 turns or 3.5 turns. It seems tuning by ear isn't working as well as it used to. Lol.

It takes about 3.5 to 4 turns out to hear a noticeable drop in idle. Likewise anything less then 2 turns and a drop can be heard. I should add that compression has gone up since the last test about a month ago. 130 or close to it. Just checked again this morning.

Consider this topic closed. After limiting my idle screw turns to 3 turns out max, tinkering with a cylinder then taking it for a spin, the issue has been resolved. I parked it and waited about 30 minutes. Fired up with a slight hesitation but not nearly as bad as having to pin the throttle for 5 seconds. I have a smooth idle, good off idle response and mid-range is nice and punchy with good cruising feel. I might add that I also sealed up the carb boots between the motor and boot with some sealant, and reinstalled the Reed valve flaps into the valve cover, completely forgot I removed them. I could tell some excess heat was being trapped in there because of this, since the gasket for the clean air valves was essentially burnt. Live and learn. I'll be posting the back story on the bike soon enough. Thanks to everyone.