Help for a newbie to the CB - Fuel leak

[crazybass2]

Let me start off by saying that this is my first bike, and I'm a first time rider.  So my apologies if I don't use the proper terminology.

I've got a 1977 CB 750 (k8, I think, but not positive)  When I got it, it had not been ridden is several years.  I became familiar with the sohc site, and being fairly mechanically inclined, rebuilt the carb, set the points, and have done a few other minor repairs in the past year inlcuding some electrical.

The bike has been running fine save a few issues with clogged fuel filter from an old tank, and old battery (replaced), and a blown fuse.  I've noticed in the past the bike drips a bit when off, and I've gotten in the habit of closing the fuel valve when I turn off the bike.  Last week I noticed performance dropped a bit and when I got home noticed the bike was pissing fuel.  I checked out the bike and found I was able to tighten the drain screw for the 2nd (from the left) bowl about 1/8 turn.  This solved the pissing, but it still drips.  Since then, I've noticed that even after turning off the fuel valve the 2nd drain hose still drips. 

I'm thinking the drain screw isn't seating well, or for some reason the fuel is reaching the overflow.  Could this have anything to do with the accelerator valve being located on this carb?  Other suggestions?

Mike

[SteveD CB500K0]

I'm not familiar with the K8 carbs, but in general the drain screw drain the carb bowl from the bottom (ie you unscrew the drain screw and the fuel comes out of the drain screw hole). The carb overflow is different and the fuel will come out of the drain tube which should vent below the swingarm (usually right ion front of the rear tyre...)

Carb overflow is very common on old bikes and is caused by tiny bits of "stuff" (technical term there) getting stuck in the float valve and stopping it from closing completely. This is why we use fuel filters - it's easier to clear the filter than the float valve.

Shutting off the fuel tap every time is one solution, but you really need to take the carbs off, turn them over, remove the relevant float bowl and clean out the valve.

[crazybass2]

I figured that "stuff" would cause fuel supply problems, not fuel leak problems, but your point makes sense.  I do have a fuel filter, but I suppose something could have made it through.  My tank has seen better days and I replace my filter every few months.  After posting the original thread I thought perhaps my floats need adjusting and was begrudging having to take the carb off (yet) again.  I guess it's the only way I'm going to solve the issue.

Thanks for your insight.

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