81 kz1000 full choke won't increase rpms

[Guest]

So i went through the carbs cause i'm a horrible person and didn't add any fuel stablizer before laying it up for the winter. So now with full choke on, the rpms won't increase unless i turn the idle adjustment knob, and once fully warm and off choke i need to reset the off choke idle. Otherwise the kz runs great and barrels down the road like a raped ape. Any ideas?

[60ratrod]

may have figured it out, but won't know until I rip the rack out and drop the bowls to chase the enrichment circuit.

[Nessism]

Chase the enrichment circuit, in particular the pick up tube. Make sure the passage in the float bowl is open as well.

[60ratrod]

Just did that tonight with some .020 safety wire, along with the passages in the throat by the butterflies just for piece of mind and no change. I also blew 40psi of compressed air through the choke circuit from the diaphragm area with the choke plungers fully open and plugging the port in the throat to make sure i was getting air out of the choke emulsion tubes in the bowl and i was. But half choke works as it should. Also, it turns out i lied about no rpm return dips after a throttle blip, i didn't notice it when i did the sync on sunday. It was a little too rich at 2.5 turns. It's at 2.25 turns and is much better.

Half choke ramps the rpms up as it should when warm, full just kills the motor. When cold, full just makes it run as though i don't have the choke even set.

What a flippin head scratcher.

[tkent02]

The choke adds both air and fuel, a separate very rich mixture from a separate tiny little mixing chamber. There are both fuel and air passages to this little chamber. If the air passages are partially blocked it will make it way too rich even when it's cold, this may be what you have going. 1/2 choke it sort of runs OK, full choke it just can't. What you really need to do is disassemble the carbs completely, dip them or use an ultrasonic cleaner, do the whole procedure. Next time you are contemplating being a horrible person and parking the bike for months, disconnect the fuel line and drain the float bowls, it will run fine when you go to start it up in the Spring.

[phydeauxmutt]

How much of an RPM increase are you looking for? In your first post you basically say the RPMs don't increase. Later, you say "Half choke ramps the rpms up as it should when warm". It sounds like there is at least some
affect when you activate the choke. Have you tried using just half-choke to start?

Personally, I like to keep the RPM under 2000 if possible, while starting the bike. In reality, if it runs smoothly, even at 1200, I would not worry about it.

[60ratrod]

well I did do a full strip down on the carbs and did a hot soak on each body for 2.5 hours and ran 4 480 second cycles. once the bodies came out and cooled enough to handle I blew 40psi of compressed air through all of the passages, blocking off what I would need to with my fingers to make sure air made it through the passages. the only parts I didn't run air through were the choke circuit ports, which I should have. and the brass bits got the old fashioned berry's 24hr dip. once everything was out of the dip and sonic cleaner I ran carb cleaner through all of the jets and passages and then more compressed air to remove the carb cleaner from the passages. then bench sync'd, and finally vacuum sync'd

mutt, normally when I hit full choke from a dead cold start, full choke would run the rpms up to 4k or so rpms, which I would let run for about 3-4 seconds before bumping it down to half, half for about 2 minutes, and then idle. I'd let it warm up before I got all geared up to go down the road(jacketon/zipped up, helmet on and strapped, sunglasses, and then gloves). and tbh, I haven't tried just half choke yet, I was just more concerned with the full choke thing. i'll try that tonight and see if I can get it going on just half