Topic: CB550 starting cold problem

[Grey]

I finished up the 550 several days ago. I've had a problem starting it cold. I may be flooding it. I noticed that there is no fast idle when the choke is engaged.  I close the chokes and it just cranks and cranks after setting a few days. So I open them half way or open throttle a little what ever and it just cranks. Once started I have to turn the idle screw about one full turn or more to keep it running for the first minute or so. After that I can shut it off and it fires right up with in a half or one full revolution. It will start that way from then on during the day.

I noticed that the chokes don't have a fast idle cam or an accelerator pump. So do you have to turn the idle thumb screw some first before trying to start cold? Carbs are 069A's. What's the trick? I have the carbs sync'd right on and the idle air screws have been adjusted for max rpm individually. All circuits are open and clean inside carbs. All manifolds are soft and tight.

[EricHa]

I'm having the same issue, and am going to take off the airbox and see if the choke is actually working. It doesn't seem to make a difference.

[Grey]

Well I went out today, after it's been sitting almost two days. I turned the throttle screw at least one full turn. Put on the choke and hit the key. Two revolutions and it fired right up and was about 1800rpms. Turned the idle down to about 1300 and had to put the choke on half. After a couple of minutes choke went to off and brought idle down to 11-1200. Bike just purred. No clutch noise from oscillations or lifter noise.

So I don't really know. Unless the throttles need to be a little open but not much to get the right A/F flow. Most choke systems do have a fast idle cam or what ever. Just thought of something. I wonder if reading the owners manual would tell me the cold starting procedure. You know, when all else fails read the f#$%ing manual.

[TwoTired]

So do you have to turn the idle thumb screw some first before trying to start cold?

No.  Just hold the throttle open a bit during warm up.  You do ride with your hand on the throttle don't you?

Carbs are 069A's. What's the trick? I have the carbs sync'd right on and the idle air screws have been adjusted for max rpm individually.

And that is wrong for these carbs.  If you did this to the extreme (as I have tried), I expect you also have issues with the engine taking throttle at low RPM.
These carbs don't have accelerator pumps and sudden slide openings starve the engine for fuel.  The idle mixture must be set rich-side to compensate.

The 550's don't need to sit idle for a warm up.
Suit up ready for ride, get on, apply full choke, crack the throttle a bit, and start the engine.  Keep it running with the throttle and partial choke as you drive off.  In a block or two depending, on OAT, you won't need to hold the throttle off the idle stop (which is adjusted when at full operating temperature), and the choke will have been incrementally reduced during initial ride.
It warms up faster under load and the engine working.  And, unless you are using 50W oil, driving while cold is of no consequence.  Just don't be drag racing until it gets to operating temp.

Do use the D7EA heat range spark plugs.  You'll have a bucking beast using D8EA during warm up, and likely not want to ride it until it is warmed up stationary.  But, it wasn't made that way by Honda.

Cheers,

[Grey]

Thanks I do have the d7ea plugs. I didn't notice any hesitation when rolling throttle on at different rpms and loads with them set this way. I may have brought them up to high rpm then like a 1/4 turn in. It's not my bike and the guy who owns it lives about 100 miles away. So it has to be perfect when it leaves here. I'm going to ride it some more to get a feel of how it wants to respond and to make any adjustments that are needed.

I got to say this thing fires right up 1/2 to 1 revolution when it's warm or hotter. Pulls right to 9500 without missing a beat. I'm at a disadvantage because I don't know the bikes characteristics. It's been awhile since I worked on an old CB bike of any kind.