The International CBX Owners Association

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

real6 wrote: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

real6 wrote: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.

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?

real6 wrote: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.

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.

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

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.