Hi Guys.I have a CBR1000F-J which has been in my posession since 1991.The bike has never ever been any trouble and flies through it's annual MOT every year.The only problem is that a few days ago it decided to start playing up after a few years in the garage.It started fine after 3 pushes of the button but then fuel started dripping from the screws holding No 1 and 2 carb float bowls.I stopped the engine and looked at the floats in 1 and 2 carbs and couldn't see anything wrong so put it all back together.Started the engine again and all four carb float bowls were leaking?? It only leaks when the engine is running and isn't a static leak.I really dont know if it's dirt in the jets (if it is then how is the fuel getting under the carbs) or if the float bowl "O" rings have given up,once again they look ok but I know that's not to say they are!! Any help would be gratefully received as One carb gasket kit is £37 (about 45-50 dollars).

 

When you say it was in the garage for a few years, do you mean without running during that time ? Either way it's pretty realistic to expect that the gaskets need to be replaced. Seeing as it is 20 years old this year, and having to replace $200 worth of gaskets is a pretty low expense to have to pay. I'd also purchase the "O" rings that go on the fuel lines to the "T"'s in between the carburetors. They get hard and brittle and since you're going to be tugging on the fuel lines, they're apt to leak. Better safe than sorry.

As for only leaking when it's running it could be because it has a vacuum actuated petcock and only opens when it's running.

PS
I'm an owner of a 1994 1000F.

 

Float valves are gummed up and dirty imo

 

It'll only leak when the engine's running because of the vacuum operated petcock.

+1 on the float valves. They're just not closing when the bowls are full. Try some of the seafoam stuff that some of these guys swear by (I've never used it) and run some fresh fuel through it.

Leave it overnight and, if you're lucky, the gummy crap might have disolved. If not you'll have to pull the carbs out and clean them. I've had mine off several times playing with my jet kit, and haven't put a gasket kit in yet.

If you do have to strip it, put new fuel lines on at the same time, if they're original, to save yourself some grief later on.

 

Yep, float valve is gummed up is the most likely problem. If it was the gasket rubber or the 'T' o-rings it would leak to some degree with the fuel petcock on.

HOWEVER, when the o-rings on the 'T's first start leaking it will only be under pressure (engine on fuel pump running). It will look ALOT like the bowl gaskets. Fuel will drip from the inside front corners of the bowls (at first). So replace them anyway. Should cost less than a pint of beer to get new ones.

 

Somebody mention beer?

 

Thanks a million guys.I appreciate your time and replies.I am gonna check all of your suggestions out and hopefully nail the problem in the next few days.

Some good advice in there.

 

Where's the front of the line?

 

Yup...floats are gummed up & sticking. They will break loose now that you've run fuel through them but since this IS the case I'd pull them, clean them & replace any gaskets. Then run Seafoam in your tank more often, especially if you're going to let her sit for any time without starting her. My bike loves when she gets a shot of Seafoam & so does my wrist.

 

Try tapping the bowls with the handle of a screwdriver!