Topic: Dripping bowl

[thelowmax]

So, I've cleaned the carbs on a CB750k that recently bought. It took a little finessing and finally a squirt or two of starter fluid, minus the air box, but it started and runs pretty smooth. The problem is that the #1 seems to be constantly dripping gasoline. Maybe a drop, once every 5 or 10 seconds but constant. What's going on? Is the float too high? (or is that low?) I appreciate any help but, I'm more of a "take it apart/clean it/put it back together" type, so if you get too technical, I may just pick up my brontosaurus bone and run.

[Nic]

My easy assessment is to turn on the fuel tap n wait a minute for the bowls to fill, turn the juice off, take the offending float bowl off careful not to spill any juice, if the level is more than approx 1/4" from the top it "may" be float level and juice is coming out the overflow tube but from your description I reckon the fuel Tee O rings are shot, 7 x 2 mm is the size, there are 4 on each of the two Tees that the fuel lines connect to, replace them all.

[goldarrow]

Where is it dripping from? Try tapping slightly with rubber mallet on the side of the carbs and see if it will stop dripping

[Bodi]

Each bowl is filled by a tiny needle valve shut off by a float that pushes the needle in when the fuel is at the proper level. The overflow tube will drain fuel that's filled the bowl too high before the fuel pours down the intake and either fills the cylinder or dilutes the oil.
Possibly the overflow tube is cracked, this is not uncommon and easy to fix, you can cover it with a hobby shop brass tube with a bit JB Weld smeared on the inside one.
If the level is too high with the float tang (this presses in the needle, you bend it to adjust fuel level) adjusted correctly, the valve is leaking. Misadjusting the float enough to start overflowing would be difficult and it would probably do more than drip. The valves leak from wear and more usually from getting bits of rust or other crap in the fuel stuck inside. If your tank is rusty or the petcock filter screen is damaged you can expect repeated leaking. Adding an inline fuel filter to avoid that is somewhat controversial here but has never caused a problem for me.
The high fuel level can cause plug fouling because the engine runs a lot richer with a high carb bowl fuel level. At high throttle highway speed it's not an issue because the carb will need more fuel than the leak supplies so the level will drop to normal. Idle or low throttle riding may not use enough fuel to drop the level to normal.

[thelowmax]

I'm off to the garage to assess. Thanks guys. I'll report back.

[PeWe]

The float bowl might be a little bit off against the gasket. I do not know which carbs you have, but mine OEM CB750 K6 bowls are snapped on. I remember that it was possible to mount wrong and fuel leaking. Snap off the bowl and mount it again. (petcock off before)

[evanphi]

The float bowl might be a little bit off against the gasket. I do not know which carbs you have, but mine OEM CB750 K6 bowls are snapped on. I remember that it was possible to mount wrong and fuel leaking. Snap off the bowl and mount it again. (petcock off before)

I had this happen to me by accident before. I took #1 bowl off to check jet size while on the bike, and when I put the bowl back on I pinched the gasket a little funny... fuel on and BIG drips. I took the bowl right off after shutting off the fuel, and I just used a bit of saliva on the gasket to keep it up high and seated correctly.