Topic: Float level question

[mossen]

I have a 78 CB550K, the float level is supposed to be 12.5mm...I set it to 12.5 using a float gauge with the carbs upside down on the table. I double checked this when I installed the carbs, I did the clear tube test on carb #1 - I put some clear fuel line on the drain valve and opened the drain screw. The fuel level is 16-17mm below the top of the bowl...

So, my question is, is the fuel level supposed to be at the top of the bowl or is it supposed to be 12.5mm from the top? Or is this not a reliable way to check? The bike starts easily and runs smooth although it seems to not have much power for a 550 (due to leanness maybe?)...oh and BTW the jets are #105s, installed by a PO, not sure if that has anything to do with it. I think he may have overcompensated on the mixture, the stock setting for #90s is 1.5 turns, he's got them at 3.5 turns...

mossen

[steam-powered man]

my bike has a rack of pd-46a (x46a) carbs from a '78550k.  it is my understanding the float height should be 14.5mm when the float tab 'just' touches (but not compresses) the float needle tip.  i used to set my floats with the rack upside-down on the bench, but now feel this may be in error, as the weight of the floats may be compessing the float valve spring just a bit.  i set floats now with the rack slightly off vertical.  a/s screw should be 2t.

i just cleaned the idle circuit over the weekend, set the floats precisely and the bike has never run better.

good luck in your endeavors,
bobp



ps:  you will need to supply exhaust type for tuning help here,
   

[mossen]

shoemaniii...I have the stock exhaust on my bike. As for the mixture screw, do I turn it tighter for more air or tighter for less air?

mossen

[steam-powered man]

if the airscrew is on the airbox side of the carbs, turning screw out will lean mix.
if the airscrew is on the engine side of the carbs, turning out will enrichen mix.

there is a pantload of info on this site.  click on the "website" link above, then under the "navigation" heading, click on the FAQ link.

   

[mossen]

I thought the mixture screw was the screw on the bottom of the carbs between the two forward float bowl screws...am I wrong about this?

So I tightened these screws to 2 turns out instead of 3.5 and it seems to run stronger now but it does give a small backfire/misfire at low RPMs...anyone know the answer to my previous question about the float level?

shoemaniii, I'm pretty sure the floats are supposed to be at 12.5mm on a 78 550...do you have information that says otherwise? I thought about doing the floats sideways instead of upside down. I watched the needle spring carefully as I tilted them back, and I couldn't see any compression of the spring...Either way its done I'm sure its fine.

mossen

[steam-powered man]

the adj screw is located between the 2 float bolt screws, on the engine side of the carbs.   turing them out will enrichen.  i got the 14.5mm float ht from my honda service manual.  someone else can verify,
bobp