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Discussion Starter · #1 ·
just a quick warning to you all, as your bikes will be coming to the same age, and experiencing the same issues.
on friday night, at work, one of the groundsmen came to tell me my bike was leaking fuel, i ran out, and sure enough, a constant stream is coming out from somewhere, but i cant tell where, its just coming off the bottom of the airbox.
i turn the tap to on (instead of res) and put her up on the center stand, and all seems good.the leak stops, so i go back in to work.

i come out at 9pm, key in ignition, choke on, thumb the starter, and on the first compression stroke, she locks up solid!

its a bastard hydraulic lock, where one of the cylinders (or more) has filled with fuel, which is preventing the cylinder from cranking.
im lucky it was the first cylionder to go on a compression stroke, so the starter never got an opportunity to build up speed or it could have bent stuff internally!

new vacuum diaphragm for tap is about 24 GBP, so probably worth doing before it goes!

i tried to fix it myself, and all seemed ok inside, so i put a heavier spring in, and it would be closed until you applied vacuum, then it would stay open, no matter how big a spring you put in there.
the only thing i can imagine that is causing it to stick is that the diaphragm is now too flexible, and it is sealing up the normalising pressure hole, that allows air back in to let the plunger return.
 

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I'm thinking that you have other problems that you should address. If the vacum tap simply failed, that would be just like turning the tap to prime. gravity force is on the fuel, but the carbs shouldn't let any more in than the float will allow. That is, if your floats and float needles are functioning properly. Appears that one or more of your float needles stuck open allowing the carb bowls to overflow and then filling at least one cylinder with fuel. If it were me, I'd pull the carbs and fix that float, before it happens again when you happen to switch the tap to prime and forget you did so! Good luck.

Bernie
 

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Discussion Starter · #3 ·
to be honest, i am on the look out for a cheap second bike so i can put the tona away, and give her the overhaul she deserves
 
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