HondaCB650

Welcome here!
First make sure that you really can pull the choke completely. Pull the knob completely, then go with your fingers between the carbs and try whether the lever might go up further while the cable is already completely out. The choke cable might be adjusted directly at the carbs, especially it might get loose there.
Second the choke will open the throttle very slightly just before its full out position. So have a look for a slight movement. If it does not move, you may use the idle adjustment at the right side of the carbs to open the throttle a slight bit (just 1 to 1.5 turns). You need to turn back that when warm, however.
Turning the throttle (independent if starter is running) will spray fuel into the intakes. Do at least 5 twists with the throttle and try to start, choke pulled completely. Push the starter for a few seconds. It may sputter and go out. Just repeat twisting the throttle and pushing the starter. Next time it may sputter a few seconds longer. Don't try to enhance twisting or starter turning time as you may flood the engine. No need to hurry, give your battery some seconds to rcover. Just repeat until it stays alive, I'd say 5 times this procedure will do the job if nothing is really wrong.
Closing the fuel cock about 500m before you stop will guarantee fresh fuel for the next start after some standing time.
Good luck!

Thanks for the help, guys.

I get the idea for the throttle "pumping." And I'll check into the choke cable when I get back out there. I think winter's decided to have another go at it in these parts.

On the matter of the starter fluid, you make it sound so easy Arcangel. Just spray it in and start it. Someday I'll understand all this, but for now, the only airbox I can think of is the one with the filter in it. Do I spray it in the filter? Behind the filter? And technically speaking, how does it work? I'm just curious, really. I've heard it can be dangerous stuff to use...

Greetings again!

Good news! She fired up and ran well today. Volker, your idea was just what I needed. Pumped it five times, and there she went.

Thanks again!

Kool Glad to here you got it going.

As to the spray for future use Yes spray it in where the filter is and no you don't have to remove it.

Good to hear that your problem is solved now. Have fun!

Me again ...the original questioner. I'm glad to hear that others have had success with the tips passed on by other forum members. I haven't tried the successful advice myself because I'm waiting for the replacement solenoid to arrive in the mail. I didn't want to try starting while hot-wiring the solenoid.

While I appreciate that the advice worked, I wonder why that cold-start process is so much different than that recommended in the original Owner's Manual (page 30) for Low Air Temperature starting? Quote: 1. Pull the choke knob all the way to Fully Closed. 2. Start the engine, leaving the throttle closed. When engine rpm begins to pick up, operate the choke knob to keep fast idle at 1,000 to 2,000 rpm. To speed warm up, open and close the throttle, keeping the rpm below 2,700. About 6 minutes after the engine starts, push the choke knob all the way to Fully Open.

So ...as you can see, these instructions do not recommend operating the throttle before starting. These are the instructions I've been following, so I'm anxious to try the forum instructios (ones that apparently work!!). Perhaps these Owner's Manual instructions are for "new" bikes.

It's supposed to "warm up" to +1 degree C here in a few days (+34 degrees F) ...so I'm looking forward to the starting up the bike (if the solenoid arrives). I'll report back ...either way.

I have found that using the owner's manual as guide is enough following all the instructions step by step has actually resulted in some rather frustrating results. When I was repairing the master cylinder the instructions to actually disassemble things were good but for bleeding brakes it took some thinking on my own to figure out things. So in short I have found that mixing the advice from the forum and using some from the manual has been helpful, the same goes for troubleshooting suspicious ideas, which the manual does not address.

When manuals are written, usually no real long term experience is available. I'd think the start procedure of the book will work from +5°C on.
And don't forget the environmental and social aspects. Possibly the air in 1980's Japanese industrial centers still contained enough unburned hydrocarbons to make it start this way well below that temperature. So please don't write angry letters to Honda as some very old Japanese guy might get cut his pension payments.

Well ..still no luck with the starting problem.

Installed the replacement solenoid, and the fully charged battery, and did the full choke and throttle-twist 5 times routine: nothing. I mean, no start. Not even a sputtering start. I tried this 5 times ..even put some gas line anti-freeze in the gas (methyl hydrate). Not so much as a cough. I'm pretty well convinced its a fuel supply problem, as there is spark at the plugs. Any other suggestions???

You are right the instructions are for a new bike as the bike gets older the carbs get dirty and seals get hard and the bike is harder to start so extra ordinary measures are necessary to start it also the bike has been drained of fuel it has to be primed to let the air out of the fuel lines and to permit fuel to flow to the carbs also fuel additives are not as flammable and vaporization is lower than the fuel its self in most cases, also additives are to make the fuel not go bad do not necessarily make the fuel have a higher ability to burn just keeps it from decomposing and separating and keeps water from collecting in the fuel and cleans the carb parts as well.
Some additives are better than others so this is a bulk statement and may not always apply to all additives .

....okay ...a lot of info there. So, how do I drain the entire fuel system and then (with new fuel in the tank) "prime" the system to get new fuel to where its supposed to be?

You could put some fuel through the spark holes (1+4 are sufficient for convenience). Then it should sputter at least.
You may release old fuel from floater bowls by opening the screws at their bottom. At least for the piston carbs, I never found any need for a special prime procedure, just open the fuel cock, wait two minutes and fuel is everywhere where it should be.
A tank say more than 20% filled over winter should not need to be drained and refilled. And if fuel level is lower, just fill it up to get enough fresh fuel fraction (before you open the fuel cock).

Well, the temperature got up to +5C (41F) today, and after a bit of putzing around, I got the bike started ...but only "kinda started". Turns out it was only running on #1 cylinder!! I noticed a puddle of fuel on the floor ...it had been draining out of the exhaust pipe on cylinder #4, and so I checked, and the only hot exhaust pipe was on #1 cylinder. What the heck is that all about. I checked, and there's spark at #4, but it doesn't seem to be firing. Do I have a serious electrical issue? I think my earlier starting problem was cold and fuel related ....

Sounds like you have mixed up #3 vs. #4 spark plug cables. #1 and #4 share one coil, same for #2 and #3.
Puddle of fuel is not the worst thing that can happen, I've blown up my rusty exhaust that way some time ago.

Okay ...that sounds plausible. However, I haven't re-arranged the wires lately. Which order should the plug wires be in? Presently they are arranged as such: from the coil on the left-hand side (as viewed sitting on the bike), the top wire goes to the spark plug on the far right (#4 ?)(no number on the wire); the bottom wire goes to the spark plug on the far left (#1 on the wire); from the coil on the right-hand side, the top wire goes to the spark plug second from the far right (#3 on the wire); and the bottom wire goes to the spark plug second from the far left (#2 on the wire).

Assuming this wiring arrangement is correct, is there a way to check to see if the coils are good? If #1 cylinder is firing (the one on the far left which had the hot exhaust pipe), then it would make sense that #4 cylinder on the far right would fire as well, IF the coil was good ..right?