Engine races when choked

OK, I'm into unknown territory here.
I have an '83 KZ1100 Spectre. The bike runs fine when it's warm. But when it's cold, if you choke it to get it started it revs way up, like 4,000 RPM. If you bring the choke in enough to bring the idle down, it dies. It's a dance keeping it running until it warms up.
I had the carbs rebuilt by Rick West at OldSkoolCarbs (pics) , but it doesn't seem to have helped any.
Once it was warmed up I set the idle and balanced the carbs. It runs pretty well once it's warm.
I had one of these bikes that I bought new back in '82, so I know what it should be like... This is an issue I've never had to deal with before, so I don't know where to start looking.
Any suggestions would be greatly appreciated.

Ok Ill shoot from the hip

Sounds mostly normal , Every bike I have reacts to choke slightly differently , its only to get the bike started then the circuit is not used.
It may need a good valve adjustment then rebalance the carbs but if it runs well once warm just enjoy riding it.
If it takes an unaccessibly long time to warm up the air/fuel screw (dont know which you have on that bike) may need some tweaking or a new pilot jet, pilot jet seems unlikely if it runs well at low speed low throttle position.

My Kz revs up like that, II keep my fingers on the choke and adjust it for the first 20 or 30 sec utill it stabilizes a bit, then ride off on about 1/2 choke for 1/2 mile or so and its good to go.
My GS starts on full choke put it to half and it idles nice I ride it until I notice it stumbling a bit then shut the choke off.
My H2 starts choke on then shut it off right quick!
The Harley is the worst LEAN LEAN LEAN and the choke closes automatically so you have to hold it for a minute or two until it will stay running.
Once warmed they all run very well.

A high idle on choke is a feature of the BS Mikuni family of carbs. Just push the lever down a little once the idle starts to race.

Nessism wrote: A high idle on choke is a feature of the BS Mikuni family of carbs. Just push the lever down a little once the idle starts to race.

The problem is that there's no middle ground. If I push the choke in at all to bring the idle down, it dies. It's either revving at 4,000-5,000 rpm or it's stalling.
With my VStar (and my original Spectre 30 years ago) I can do as you suggest - the choke is a range, and I can find a spot that starts off reasonable (~1,500-2,00 rpm) and push it in as the engine warms. Not so with this. If it's choked enough to keep the engine running, the engine runs away.

Pilot circuit.
Steve

SWest wrote: Pilot circuit.

Can you elaborate a bit?

padarjohn wrote:

SWest wrote: Pilot circuit.

Can you elaborate a bit?

Don't want to put words in Swest mouth.
So this is just me thinking;
Have you adjusted the screws on the carbs?
This needs to be done after all other maintenance , valve adjustment, carb syncs , good plugs , no air leaks, clean air filter etc.
If the pilots are not adjusted correctly, (correct size and correct screw adjustment) the transition from the choke circuit to the idea circuit may be way out of wack.

Air box or pods??

JOE MKII wrote: Air box or pods??

Everything is stock. So air box.

Typically, the bike should tolerate half choke without killing the engine. The adjustment is very temperamental though. Maybe your carbs have partially blocked choke and/or pilot screw passages? Even a little hidden crud can cause various problems.

Nessism wrote: Typically, the bike should tolerate half choke without killing the engine. The adjustment is very temperamental though. Maybe your carbs have partially blocked choke and/or pilot screw passages? Even a little hidden crud can cause various problems.

While there's always the possibility, I wouldn't expect there to still be carb issues. You can see from the pics I linked to in my original post the level of detail that went into the rebuild. Rick has been doing rebuilds for over 10 years and has a solid reputation.

Also, it idles fine once it's warm. If it were a pilot circuit issue I would expect to have problems there.

Is the bike stock or modified in terms of airbox, air filter, and exhaust?

Nessism wrote: Is the bike stock or modified in terms of airbox, air filter, and exhaust?

As I said earlier, it's all stock - airbox, exhaust, carbs (needle valves, etc). The only thing that's not stock on the bike is the rear shocks - someone had swapped the originals for some ugly shocks with chrome springs. I have a set of (supposedly unused) original air shocks I got from eBay, but when I went to use them I realized all the oil had leaked out. So I opted for standard shocks with black springs until I figure out if there's anything I can do with the "correct" ones..