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Discussion Starter · #1 ·
Hi Guys,



I'm helping a gentleman fix his leaky 88 Yamaha FZ750. The overflows on these bikes connect between two carbs, so I don't know which of the two carbs it's coming from. It's the float valve overflow from what I've seen, and I've had the floats out several times. I tried adjustment at first, to no avail. Then, I slightly sanded down the needle valves and brass seat and then polished with cloth on the dremel. Put it all back together and that seemed to fix the problem. Now, it's back to leaking just a few days later. The float valves seems in good condition and I don't know how they would be sticking. Can anyone shine some light on this for me? Should I just buy new valves? Thanks guys!
 

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It sounds like there might be gunk still in the fuel delivery lines. I'd make sure there is fresh gas, and clear the lines, Make sure there is a filter before the carbs to prevent any residual bits passing by. Check the tank for internal conditions. Then redo the carb cleanout, and see how things are.



Joel in the Couve
 

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You sure that you are setting the floats properly?? Might have them set at the high setting instead of the normal setting. Another thing, sometimes these gaskets have a little extra "burr-like" to the inside of the gasket sealing area. Make sure it's not holding the float.



I'm not wild about "sanding or dressing" any of the float needles as many have a rubber gasket area which can get damaged from this operation. this leads to leakage in tha carb/s. Sometimes having a good magnifing glass helps to really look at the contact surfaces of all this stuff. Little "nicks, scratches, our of round or frayed" rubber components are crical in the carb. Mmm, that thing have Mukuni's?????



LT2
 

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So it has a brass needle and a brass seat? There should be rubber there somewhere. If you have a brass needle without a rubber tip, then you should have a rubber 0-ring for a seat. There is your problem.
 

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Discussion Starter · #5 ·
Sorry, I should have explained better. The needle has a rubber tip and the seat is brass. They are mukuni's i believe. Good idea on the "burr" in the float bowl. I'll surely look into that. I've adjusted and readjusted the floats, and these carbs look as though they would not be able to overflow unless there is something wrong. The overflow hole is well above the top of the floats at the top of the cycle. Thanks for the tips guys! You fellers are awesome. I think I will just order new floats and a fuel filter. Thanks guys!
 

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May be something as simple as a piece of crap getting stuck in the float needle seat. I agree you should flush the tank and paybe stick an inline fuel filter in the line to the carb if possible
 
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