D.A. newb with yet ANOTHER leaky float bowl Q

[pojobey]

I promised myself my first post wouldn't be a crybaby help plea, especially on a topic that has been covered many times. But here I am smelling of gas and asking for help all the same.

I am a new owner of a '67 CB77. The carbs were in dire need of a rebuild and I did so using the Keyster kits and tips from this forum such as reusing my old jets, visually sighting the float heights (thanks lm), etc. I have what I believe is a bowl gasket leak - a slow but persistent weeping from the front of the bowls. One mea culpa is that on the first go 'round I put a film of light oil on the gaskets. Don't ask me why, just an old habit with the wrong application.

Tim McD suggested I bend the clips on the bails a little to increase the tension. It helped but obviously not enough. I then asked a local vintage hero for advice and he suggested running a q-tip with brake cleaner around the upper seat (carb side) to get any left over gasket material. I also cleaned the gaskets in Simple Green solution until they were squeaky clean (credit Ed Moore) in case they were moving under compression.

The only thing left I can think of is to check the sealing edges of the bowl with a straight edge or try different gaskets. I suppose it is also possible that I made some light scratches on the seat getting the old crusty gasket out. It almost seemed like there were two gaskets in there or maybe one that delaminated. Also, I should mention that this leaking happens as soon as the petcock (also rebuilt) is turned on when the bike is cold. No fuel comes out of the overflow/vent tubes.

I've been jacking around with this problem for a couple weeks and it's beginning to bum me out. I'm no mechanic but I can't believe this is kicking my ass.

Thanks for listening.
-pat (Simpsonville, SC)

[pojobey]

When I did the float height measurements I did so at the point where the tangs first touched the float valve. I actually suspended the floats with my finger at that position while measuring. It is possible that I was taking the written advice too literally…

Should the floats be *resting* lightly on the float valve, unassisted?

Thanks,
-pat (not a bouncer/wanker/etc)

[cadman]

Yes.

[gramey7]

I had the same problem with my CL77; tried everything you have. What solved the problem was buying Honda brand gaskets. Don't know why that worked since the aftermarket ones looked about the same.

[pojobey]

Thanks, just got the same advice from Bill Silver so I ordered a set from my local Honda dealership. Also feeling optimistic about resetting the float heights. Thanks for sharing your experience with your CL77 (helped my mood a lot!). Hopefully in a few days I'll have some progress to report.

-pat

[pojobey]

OK so a few days was actually a few months. Winter was cold and I was a sissy. But now it's spring and I'm determined to fix this leak.

Got the new (Honda) gaskets but first I wanted to check the float height. I get 1" from the gasket seat to the top of the floats with the carb held near horizontal. This is after using the sight along the main jet holder method.

That was a bummer because I was hoping to see it less than 7/8" (22.5mm). If I set it to 7/8" then the floats are almost touching the upper body and that will also make the gas level even higher (right?). If you pointed a gun at my head I would say the floats need to be even with the top of the main jet, not the holder in this case. But from all I've read that is wrong-headed. I could use a pointer.

-pb

[48lesco]

Should be even with the top of the brass jet holder (not the jet) with the tang just touching the spring pin, not compressing it. At rest, the fuel level in the bowl shouldn't be as high as the gasket anyway. What kind of shape is your fuel tank in? The issue is usually some kind of debris in the fuel preventing the needle from sealing. Even with the bowl and screens in the petcock fine particles big enough to foul the valve will get through. You could use in-line fuel filters for a while to solve this. Sometimes you can open the bowl drains and flush some fuel through and it will get better. It may solve itself by running a couple of tanks of fuel through it and cleaning out the petcock and carb bowls periodically. Good luck - it can be a frustrating problem, and be sure to shut the petcock off before you shut the motor down.
-48