Topic: float tang's effect on float needle and spring

[bigredscowboy]

The short form of my question is that adjusting the float tang to reach spec float height (Honda FSM - 14.5mm; Clymer's - 22mm) directly affects the travel of the float needle. The question then is how low should the float needle be dropping out of the cylinder (if at all) and at what point should the spring be entirely compressed when the float bowls are full?

Background: New to this forum but longstanding member of therangerstation and r6-forum, among others. I've done a lot of searching and answered many of my questions but not these.

I am working on a 77 CB550F, which had excessive gas leaking out all 4 carb overflow lines (floats set at 22mm) and a 3000rpm idle with the idle screw all the way.  I am doing this for a friend who is getting married as a part of his wedding present. The floats have been 'adjusted' a lot so the tangs are at widely varying depths (some above the thinnest metal strip and some below).  I can't be spending loads of $$$ on this so I need these floats to work rather than buying new ones.  It seems as though someone has torqued the floats rather than the tang to adjust height which means that when all are adjusted to the same height (22mm) the springs on the float needles are not all compressed to the same amount when i push the floats as far up ('up' with regard to them being installed) as they will go. 

1. Should the tangs run closer to parallel (above the rest of the metal, see first pic) or below (2nd pic)



2. Being new to carb injection, I have deduced that if the bowls are overflowing, I should increase the float height in order to shut off the gas flow earlier. Is this right?

3. At 14mm the floats are at the top of the chamber without the tang even beginning to compress the spring. Could this spec be accurate. Does not the spring in the float needle need to be fully compressed to stop gas over-flowing into the bowl

4. There is a metal stop on one side of each float that seemingly prevents the floats from dropping so low as to allow the float needle to fall out. Is this in fact the case and should I adjust this accordingly?

[Don R]

I would start with them closer to the top picture. I'm not familiar with the 550 but look in FAQ under carbs, there are posts in a couple  places there, or search carb float level. If the overflows are connected to the drain screw you can slip clear tubing over them, open the drain and visually see the float level. It's easiest to measure with the carbs off and on their side.

Look in trick tips and how to's also.

[cougar]

Hey bigred ; Although I doubt it would be doing on all 4, check to make sure your overflow tubes aren't cracked. With the bowls off, plug one end of the overflow tube and blow in the other end and listen for air. The crack in that tube Can be Extremely hard to see. Just a thought.   ...cougar...

[Duanob]

Your top pic looks correct.

First off you need to figure out which carbs you have. Look on the mounting flange on the carb where it mounts to the carb bracket. There should be a number stamped such as 087 or 022A or 627. I know in 77 the F and K model 550 had two completely different carbs and you never know what the PO did if he ever replaced them. The PD carb for the 77 K model float height is 14.5mm from the carb body to the top of the float when the carb body is turned at an angle where the float tang just touches the float needle but not compressing it. The 77 F model uses the 087 carbs or similar (from the looks of your float that's what you have) and the float height is 22mm measured the same way. When you get the carbs put back together I always shake the carbs a bit to make sure the floats aren't stuck. Then when the carbs are mounted on the bike use a clear tube float measuring tool to make sure the floats are working and set correctly.

When you have the carbs apart make sure the tips of the float needles are clean and no scarring and the float jets are clean. Any tiny bit of crud and the float valve won't shut off properly. And FWIW make sure your floats are gas NOT logged, although it doesn't happen much to plastic floats it can happen and if they don't float well you will never get the valve to shut off.