Hopefully, you cleaned and re-used all the stock brass, and have the jets in the correct positions.....
IF SO, and the mixture screws have no effect, the idle passage is still dirty or blocked.......
Cranking the throttle-stop cable/adjustment in all the way has opened the butterflys enough that some fuel is being drawn through the primary jetting, but only enough to maintain the 900 RPM......

You NEED to re-clean at least the idle circuit passages and jetting......

 

I did re use all the stock brass. I found problems during the rebuild and corrected them (dirty emulsion tubes and bad diaphragms). The thing is, the idle adjustment and mixture screws were working fine before, I just had the problem with some times hanging idle or idle racing up on its own (which does not happen now).

So it seems the idle circuit was not obstructed before, and I cleaned the carbs in my ultrasonic cleaner so I don’t think they would have gotten worse, right?

What I did during the rebuild was set float height 20mm, resolve diaphragms and bowl gaskets, and general cleaning. I did take the left carb off the rack so I could access the felt washers on the throttle shafts and oil them.

 

I just removed both mixture screws to inspect because one was harder to turn than the other. That one happens to be missing the little rubber o ring. Which is odd because I definitely know it was on there when installed. And it’s nowhere to be found. I checked the bore of it’s hole and it’s not in there.

 

Got two replacement O rings for the mixture screws. Going in much easier now. It did not change anything, though. When I start the bike from cold, it idles "normal" around 1200 for maybe 1 minute then falls to about 900, stays there, then dies. You're right, it's like I either don't have an idle circuit at all, or the idle adjustment screw is just not doing its job.

I am fairly certain I would have noticed a missing O ring on the mixture screw on reassembly, so I'm confused about where that went. I looked in the passage and it looked like there was no room for the rubber to be in there.

Is there ANYTHING I can try before taking the carbs back off? If I take the carbs off, what exactly am I looking at fixing?

I had to take off the throttle butterflies to oil the felt washers on the throttle shafts, and maybe I installed them in some way where they are blocking the idle passage? Like they're on the wrong side? That's all I can think of, but I don't know if that's possible.

 

Have you tried re-setting the idle to 1200/1300 once the engine has warmed up?.......

 

I have maxed out the idle adjustment, so i would think it would be in xcess of 1200 rpm once warm (and I have had it warm).

 

Fuel level NOT reaching idle circuit jetting or idle circuit blockage........

Are the mixture screws at the factory standard starter settings?.....

 

Yes, they are set at 1 out to start (manual 1-1/8 out)

 

How was it running BEFORE you tore into the carbs?
Is the timing set proper? Shot in the dark?
I do know it doesn't take a whole lot to clog those jets

 

Where are you adjusting the Idle Speed?

Your original post mentions using a CABLE TYPE Adjuster?

There should be a Spring Loaded (to hold tension) Idle Speed Screw on the end of the Throttle Plate Shaft.
That is where the Idel Speed is adjusted by opening the throttle plates directly at the shaft.

 

Correct, there is a thumb screw with a slot for a screwdriver on the left side of the carb assembly of the left carb. Turning clockwise will increase the idle speed of that particular carb and increase overall RPM at idle. HOWEVER, you must then use a LONG screwdriver through the hole in the frame to adjust the right carb to synch them together. If they are not synched properly, you will notice that the RPMs will go up when you twist the throttle, but then stay there and come back down very slowly, if at all.

Check out page 20 of the Honda Service Manual or pages 48-49 of the CB360 Owner's Manual.

 

The screw in cable adjuster I believe is really only used to adjust for throttle slack, not for changing idle speed through the carburetors.

 

Yendor, the throttle shafts come together in the middle and the cable (like a speedo cable) I ok the left side of the carbs near the exhaust. When you screw this cable clockwise it moves the ends of the throttle shafts open. So I am certain it adjusts idle. I think we’re just having trouble understanding each other because “cable adjuster” sounds like the parts that take slack out of throttle cables.

Carbs are synced, rpm’s rise and fall nicely. Maybe I should post a video.

 

Please take a look at the video below. You can hear me describing the problem with my friend.

 

(2) Questions:

Is the Choke - "ON"?

Are you letting it overheat while playing with it?

These are Air Cooled motors and don't really like to be running too long standing still.
The Simple fix is to place a BOX FAN on a Milk Crate in front of the bike while doing adjustments that require the motor to be running.

 

1. Choke is not on (closed)

2. I haven't run it for long enough to overheat, maybe 10 minutes or so.

I'm going to be taking carbs off next week when I have time (maybe sunday)

 

Choke closed is ON (Choked)....

 

There’s something I’m still not clear on. Are you adjusting the idle speed with the cable adjuster or the idle speed screw (not idle mixture screw)? You said you bench set the carbs with throttle blades completely closed (touching the bore), when, in fact, they should be open just a crack with the screw(s) enough that you see a slight sliver of light perpendicular to the shaft when looking through the bore.
I bought a ‘65 Triumph awhile back that hade a single carb slide Mikuni conversion (rather than the diaphragm type like yours), and when I talked to the owner he said every time he turned a corner, the engine changed speed, usually speeding up. I asked how he set the idle speed, and he told me with the cable adjuster on top of the carb. It had a lot to do with why he was selling it. He said it’s dangerous. In two minutes I showed him that the idle speed is set by the idle screw. I put full slack into the cable, then bumped the idle screw until it changed the idle speed. Then I showed him how to set the correct cable slack with the cable adjusters, with slight movement of the twist grip before the speed changed. I turned the bars both ways a few times with zero engine speed change. He said he didn’t know how the new carb worked, but I reminded him it’s just like the Amal he removed. He still sold the bike to me saying how he’s more of a Harley guy and this one is too complicated for him. I made out like a bandit.
In your case, the idle screw(s) are outside the carb directly influencing the carb shaft rather than the bottom of the slide. They push on the piece your throttle cable attaches to.
I really hope I misunderstood what you did, but since I wasn’t sure, I shared my thoughts with you.

 

There’s something I’m still not clear on. Are you adjusting the idle speed with the cable adjuster or the idle speed screw (not idle mixture screw)? You said you bench set the carbs with throttle blades completely closed (touching the bore), when, in fact, they should be open just a crack with the screw(s) enough that you see a slight sliver of light perpendicular to the shaft when looking through the bore.

On this model of bike the idle adjustment screw is a cable. Basically a screw that is located in a more convenient spot, and that turns a cable, which has threads on the end, and acts like a screw.

 

One adjustment screw for 2 carbs... doesn't seem right.. since idle is NOT set by throttle... or external (noncarb ) parts.. you should be able to set the (proper) idle without ANY (throttle) cables as far as I know they are for acceleration..
PLEASE correct me if I'm wrong..
You would be AMAZED as to what a GOOD carb/jet cleaning will do for a old carboratiors behavior..

 

Rob, the 360 carbs are linked together (unlike the 350 version) with dual push-pull throttle cables and a single idle stop screw (the CB picture was clearer than the CL, same basic setup)

https://images.cmsnl.com/img/partslists/honda-cb360tk0-1975-usa-carburetor_bighu0044e7116_0c13.gif

 

Rob, IF you would look at the carb fiche you might understand the situation.......
His bike has a cable coupled extension for the throttle stop screw (for easier access) ...
This positions the base setting of the camwheel on the throttle butterfly shafts (interconnecting both carbs' shafts via the sync screw) that the "pull" cable from the handlebar rotates/controls.....

 

"Well THERES my problem!"...
Wow, never seen that before.. pretty cool. Thanks

 

Yeah its pretty cool until carb sync time, then it's a pain. Even with the fancy tool for the job the tank has to come off.

Sent from my SM-G973U using Tapatalk

 

Made a happy face on my tank for this reason... Nice clean 3/4 hole with a stepped cone bit.

 

I'm going to remove carbs tonight, what should I look at?

I removed the tank and dumped it and there was some sediment, so I am clearing it with acid right now.

On rebuild, I did everything by the book, with old stock brass, except I did a 20mm float height instead of 18mm, after doing some reading one here. I also have the new replacement diaphragms that you can get from CMC.

 

From the CL360 Owner's Manual: the throttle stop screw (#2 on page 47) adjusts both carbs for idle speed.