Topic: Carb question 022A 1974 cb550

[shizzomynizzo]

Hello,

I have a dilemma. I cannot figure out why my bike is running kinda rough. It loses power at 5500 - 6000 rpms.

I just cleaned the carbs, cleaned the petcock, fresh oil, fresh gas, just set the timing 2 weeks ago, along with the valves. the only thing I have not done is adjust the cam chain.

Anyway, while I had the carbs off last week I adjusted the floats. The book said to adjust to 22mm, but this is impossible on my set. when the float is extended completely, it doesn't go to 22mm. I decided to set them at 12.5mm since I have seen that number in alot of threads for the carbs. (the other choice of mine was 14mm)

Everything was fine for a week...ran great, full power etc. I went down in a ditch a couple nights ago, and after that I noticed the power loss at high rpms. It was probably was happening before that, but I don't race around too much so i would not have noticed. I already checked for vacuum leaks and exhaust leaks and there are none.

The carbs are stamped 022A on the cylinder 4 side of the metal runner tubes between the carbs and head. Not sure if they are though since I cannot get the float height to what the book says.

Should I pull the carbs yet again and try 14mm?

[Bill Vaughan]

22 mm is correct for a Type I, 022A setup.  I suspect that your problem might be with the way in which you're measuring the float height.

Take a look at the attached image and follow the factory manual procedure:  Position the float so that the float arm barely touches the tip of the float valve.  Measure the distance from the flange to the top of the float with the float level gauge  The standard value is 22mm (0.89 in).

[TwoTired]

There should be 022A stamped on each carb body mount flange top right.

22mm is the correct float height unless you have PD carbs. (Which will have the letters PD cast into it.)
Your floats should be roundish, not rectangular oblong ones like the PD style.

Are you certain the floats aren't installed upside down?

Are the carb internal parts stock or aftermarket such as Keyster?  Do you know what number the slide needles have stamped on them?

Check out the Honda CB500/550 shop manual.  022A carb style should appear as those on pages 57-67.  The PD carbs at depicted on Pgs. 174-179.

[shizzomynizzo]

I looked at that exact picture when I was doing the floats.

THANK YOU!  I figured it out. it is going to sound like a stupid newb mistake but here it is:

I used the only ruler that was laying around the garage and it was inches on 1 side, and agate on the other...NOT mm 

I am visualizing the eye rolls and laughter from you all 

For those who do not know what agate is, it is used in publishing and 1 agate is approximately equal to 5 1/2 points (on computer) or 1/14 of an inch or 1.814 millimeters. so the 12.5 agate is roughly 22.675mm.

I wasn't off that much, that's why no gas was dumping out the overflow and why it still ran!

NEW QUESTION: Will the float being set roughly 1mm too high effect the performance of the motor?

[shizzomynizzo]

Thank you guys very much, I have never heard of agate before, and have never seen a ruler with anything but inches and millimeters until now! should have known it was dumb a$$ me

I will never read a Detroit News paper again!!!
(where the ruler was from)

[TwoTired]

NEW QUESTION: Will the float being set roughly 1mm too high effect the performance of the motor?

1 mm too high should result in a fuel level 1 mm lower than required.  This should lean the mixture for all fuel delivery circuits as the fuel must be lifted higher to reach the carb throat.

[shizzomynizzo]

Thanks TT  , thanks Bill  ,

Just pulled the carbs yet again, re-adjusted the floats, reset the valves, reset the timing, and just got it back together.
As I pulled out of the drive, it started down poring, but I got to go a couple miles. IT NO LONGER LOSES POWER AT HIGHER RPM"S. The floats were a little higher than I thought...about 24.5mm and it was really running like crap.

Thanks again for all your help everyone!