Topic: CB550F - Keihin 069A Carb adjustment

[dodge2000]

Hi All,

I have a number of issues with my carbs.  1&4 are super rich at idle and foul the plugs within a minute of starting.  2&3 seem fine, if perhaps a tiny bit oily, but I'll get back to that.  When I picked up the bike it used to die when on full throttle, showing signs of leaning right out and dying.  That left me stranded by the road.  I have since started getting it back on the road.

New plugs, coils seems fine, new electronic ignition.

I had stripped the carb, but it was really clean and I don't think it was too long since it was done before.  When I looked to bench sync they had originally been set so 1&4 were 'open' more than 2&3, by almost double.  Is that normal?  At idle, does the fact they are open increase the richness? 

Second issue is the adjustment.  The adjusting screw is all the way in on number 4, but it is quite a bit open, but the adjuster on 1 has lots of adjustment left and is set at the same height as 4.  Could the adjustment arms have been put back incorrectly when they last did it?  there are a few springs in there that may have been mixed up.

I might end up taking them all apart and comparing spring lengths and component orientation.

[matt mattison]

It sounds like you have a whole gaggle of issues going on there. If the set up of the carbs in current form are unknown, I would pull them and start from square one. And have a good set of carb instructions handy as well. Make double sure your emulsion tubes under the main jet are clean as well along with the pilot.

[harisuluv]

Yes, 1 and 4 being more "open" would contribute to those two cylinders running rich.  It will affect the idle also, when you turn the throttle, all it does is raise those slides, if they are permanently raised higher than the others you are out of sync and running richer. 

If you have screws that are mixed up then that could attribute to the different levels of the adjusters.  All the springs in the adjuster assemblies should be the same size.  So you got the two big ones in each adjuster and then the little ones for the air screws.  PO probably lost some and just replaced them with some other screw, hence the different levels.  It is normal for there to be SOME variation in the adjuster levels after syncing up, this can be attribute to different variables, tension of the spring, sometimes the lever that attaches to the slides is bent a little bit, etc.  You seem to know generally what you are dealing with and sounds like you are well on your way to being up and riding again.  If you have any questions post them here and we will answer them for you.  I will try to keep an eye on this thread.

[Tews19]

What are you mains and slows? I would follow the above advice. Take the apart, and start from the beginning. The carbs are pretty straight forward and simple.

What exhaust are you running? Also, are you sure you have spark to all 4 clylinders? May die due to only running on 2.

[dodge2000]

Update on this one.

I have taken the adjusters off number one and two.  They are both the same, in terms of springs and all the parts are the same in there.  There is one clear difference.  When the slides are both fully in, the arm (the bit with the two ball joints that the adjuster fixes two on the outside of the carb body)  on number 1 is about 3mm lower than number 2.  At first I thought it was how the arm connected to the slide, but on taking these apart, they are the same.  It actually looks like the orientation of the arm itself is different by 3mm and looks a bit bent.  When I look at 2,3 and 4 they are all the same, but the 3mm difference in number 1 is pretty clear.  I can't see any damage and they seem pretty sturdy. 

Choice is to find a new one, try and bend it, or find another way to compensate for the 3mm of extra travel that one needs to be the same as the others.

[harisuluv]

It could be bent.  The deal is, that one arm being bent doesn't really matter.  That is where the adjuster screws  come in.  The positioning of that arm is arbitrary as long as they are all synced the same. 

[TwoTired]

The lifter arm attaches to the main shaft with a small bolt.  Take that bolt out and check it.  When the slides stick in the bore, forcing them with the throttle using gorilla arms can bend the small bolt and screw up the arm geometry relative to the other carbs.

Such abuse is not easy to fix.