Fuel leak at airbox

[real6]

What would cause fuel to drip from the airbox on my '79 after about an hour riding and parking on the side stand?

[Jeff Bennetts]

What would cause fuel to drip from the airbox on my '79 after about an hour riding and parking on the side stand?

there should be a line to the catch tank to except any backflow, next question is why is there a flow to the tank? a float valve not seating, overflow lines not working,routed incorrectly, clogged or missing?



stick your head in there and look around.

jb

[retrex]

What would cause fuel to drip from the airbox on my '79 after about an hour riding and parking on the side stand?

Just a guess, I am not a CBX expert. But I did stay a Holiday Inn last night. Check the vacuum line to the fuel stop valve if you still have it installed on your bike. Fuel in the line = breached diaprhagm. Fuel could be seeping out the carb intake side when the bike is on sidestand.

[real6]

Vacuum line to the fuel valve...you must be talking about an '80 and up! None of the vent lines/tubes feed into the airbox, only the drain line coming out, so nothing is 'venting' into the airbox; need to assume it is coming from a carb, but why run uphill and not just into a cylinder?

[retrex]

Vacuum line to the fuel valve...you must be talking about an '80 and up! None of the vent lines/tubes feed into the airbox, only the drain line coming out, so nothing is 'venting' into the airbox; need to assume it is coming from a carb, but why run uphill and not just into a cylinder?

Sorry, my CBX ignorance is showing. On my GS the vacuum petcock draws off #3. I assumed all Xs had the fuel control valve which also draw off a carb. I extrapolated that if the lean angle at sidestand down was severe enough and the fuel flow through the breached vaccum valve was sufficient to cause a backwash against the carb choke valve that some gas could seep back into the airbox. Also, I have recently remove the rubber insulators on my 82 CBX and there is a large amount of dried varnish residue on the cylinder head intake port openings under the insulators. This sugested that a some time there was quite a bit of back seepage of fuel. I took a shot in the dark. I missed.

[real6]

Funny, because I had just ridden a very windy section and stopped to wait for another rider and set it on the side stand (which I normally don't do) when I noticed the fuel leaking out of the airbox seam-not the overflow to puke tank. Still listening.

[stevekates]

Would the crankcase breather tube be clogged and causing excess fluid to build up a possibly be the problem?

[real6]

I don't find anything obvious, so maybe I'll just keep using the center stand...avoid that nasty 'fuel filling #1 cylinder' problem we hear about. Thanks for your input guys.