My friend's Honda CB650 has been having problems leaking gas between the needles and seats, causing gas to over flow big time! Thinking the needles must be bad, I replaced the needles with new ones which worked... for a few minutes until gas started pouring out again. I was told by the local shop that sometimes if you use some metal polish on the seats, it can help with sealing between the needles. So I removed the needles, and polished the seats with a little metal polish, but this did nothing.[:@] I know for a fact its the seats that leak. With the bowls off, if you hold the floats up with your fingers no gas will flow. But if you momentarily let them down for a second to let some gas out, then push them back up again, a couple of them will keep allowing some gas through. All the seats look good too. This has to be the strangest problem I've ever had with a carburettor.

Does anybody have an idea?

 

nope sorry bro.

 

Sounds like if there are springs they are weak, if they are the kind without springs, try bending the tab a little in the direction of the seats. They might just be not getting enough pressure. Also don't the seats have a rubber spot that seats in?

 

These float needles do have the little spring loaded pins at the ends, and they all have good tension. The needles also have the soft rubber-like tips for making a good seal. (Those tips are all in good shape considering the needles are brand new.) Even the old float needles looked to have good tips on them. The floats are non-adjustable, so there are no tangs to bend for adjustment. I never saw any rubber on the inside of any of the seats. It's an all brass seat.

I'm wondering if float seats ever develop hair line fractures or cracks? Maybe that could explain it.

 

what about any dirt or anything else getting in there. this could case openings could it not? The fuel filter is good correct

 

Everything looks very clean.

 

so no impressions or dents on the rubber tips? And it still leaks?

 

So I was just talking to this guy a minute ago in my shopwho does a lot of custom bike work, and general work. He says it's almost a guarantee thereare small rust particles collecting on the seats and needles causing an incomplete seal. I guess we'll seal thetank and find out if it works.

 

So just a small update....

After taking all the bowls and floats off again, I used my blow-gun and pressurized the fuel inlet line. This blew out quite a bit of dark specs of what looked like rust. I repeated this several times with carb cleaner until the crap quit coming out. I have since installed an inline fuel filter and sealed the gas tank with Red Kote tank sealer. I've ran the bike several times without anymore leaking. Hopefully that's the end of it.

It's always something so simple that gets overlooked!

 

congrats on the fix!