Leaking Carbs (oh God a nighthawk question)

[JonnyB]

Well not so much as leaking, more like P##sing out.

Finally got some spare time, so I thought I'd prep the wife's CB650 (yes it's the Nighthawk), ready for its MOT. It's been under cover in the shed since July last year, but what with rising fuel prices she's decided to get back into the saddle.

Anyway, no problem starting it up, even though I think the choke is stuck open, but it absolutely pisses fuel from number two carb, but only when the engine is running. Revs up fine too, and as soon as you switch the ignition off the leak stops ( I said go with it, it's still doing less to the gallon that the car - Kidding ).

Not had time to strip it yet, but as far as I can see the leak is not from the float overflows.

Has any one else experienced anything like this (Think of it as a fuel/carb/vacuum tank issue and not a Nighthawk problem)

Look forward to your advice, and any derisory comments about nighthawks.

John

[SteveD CB500K0]

OK. Assume this "Nighthawk" thingy has a vacuum fuel tap, so only leaks when the engine is running.

We need to know where it's leaking! If it's not the overflow then where?

[JonnyB]

I'll get the tank off tonight and see if I can locate it, but I've never seen a leak like this before. When you peer under the tank it's higher than the float bowls and seems to be coming from the top of the carb itself.

[matthewmosse]

Split fuel line? blocked overflow an stuck float? My 500 developed a strange thirst that ended up being a split in the (new) fuel line

[SteveD CB500K0]

Perished/split diaphragms?

[JonnyB]

Well, I'm stumped....

Just started it tonight after spending a hour clearing space in the shed to work on it and it's stopped leaking. 

[Bryanj]

If it dont leak it aint broke;

If it aint broke leave it alone!

Ta Ra problem fixed so ride it

[JonnyB]

Waiting for a new choke cable, I'll let you all know if it leaks again.