Topic: carb question

[farmlife]

Just bought a 77 cb750. The bike wasn't started for about 13 months. The carbs look real clean and the guy told me that he bought them and had them rebuilt. The carbs are from a 72. I'm having a problem with the float bowls over flowing and running out the tubes. Had problem with 1 and 4. I decided to remove carbs and adjust the floats a little. Put them back on and i guess I over did one because #3 is pooring out like crazy. My question is there a good way to adjust the floats? Once I can get this right I can start from there.

[HondaMan]

The float height on the '72 carbs (models 657A or 657B) is 26mm. This is measured from the little notch on the side of the float bowl nest on the carb's upper half.

It's not uncommon for a tiny burr to grow on the 2 little posts where the pivot pin slides in: this burr is caused by the sharp edges of the brass bracket of the floats. This can make them stick down and overflow. Look closely in there, with the parts removed, and trim off, if found, with a razor blade.
 

[farmlife]

I was looking at the shop manual and it shoulded a pic of position of adjustment. Pic quility stinks but it also states to use float level guage. Is that the 26mm you r talking about?

[Johnie]

Yes, that would be the float height which is checked with the carbs off the bike...see pic.  The height is checked with the float tang just touching the nipple of the needle valve.  That is why it is easier to do with the carbs off so you can tip them a bit to make that slight contact while you check the floats.  Click the pic to enlarge...

[farmlife]

that is a good idea for those old 3.5 disks. Thanks for sharing that

[HondaMan]

that is a good idea for those old 3.5 disks. Thanks for sharing that

He has a good point, Johnie!
Now I know what to do with some of the 2,230 that I have... 

[Johnie]

that is a good idea for those old 3.5 disks. Thanks for sharing that

He has a good point, Johnie!
Now I know what to do with some of the 2,230 that I have... 

To be honest guys, I got that idea from someone on this board a couple years ago.  So I can not take credit for it.  Sure works nice.  Just used my Exacto knife and it works nice for me.

[jimbir]

I have a picture showing the carbs positioned so the throats are vertical and the floats are hanging down on the pins. The tangs are supposed to be just touching the needles in this position but not compressing the springs in them. In the picture above, the springs are going to be compressed by the weight of the floats Which is the correct way to do this?

Thanx, Jim B.

[Slayer]

Find the sweet spot where the pin touches but does not compresses

[Slayer]

Here is the position and tool I did it with. This was before I adjusted, so that is what the float height and tool setting should not look like. I hope it helps

[Johnie]

I have a picture showing the carbs positioned so the throats are vertical and the floats are hanging down on the pins. The tangs are supposed to be just touching the needles in this position but not compressing the springs in them. In the picture above, the springs are going to be compressed by the weight of the floats Which is the correct way to do this?

Thanx, Jim B.

That picture above that I posted was just to show where you set the gauge on the carbs.  Not to do it with them totally upside down.  That tang should just be touching the needle valve nipple and not compressing it.

[Bill/BentON Racing]

Usually sideways with slight angle,neat float tool,original tool still available from Honda 07401-0010000,$23.50 in 2006 book.Bill