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Float needle issues, 1980 KZ750 LTD
- astark
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1980 KZ750H LTD
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- JR
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I would stay away from using sandpaper. At least for the moment. Do the seats look damaged ?
I have found that using Brasso liquid on a Q tip followed by carb cleaner will clean up a dirty seat and make the seal a whole lot better. If you dont have a fuel filter on the fuel line then i would suggest installing one as the tiniest piece of rust can cause a leaky float valve.
You shouldn't need to replace float needles every couple of months. Are you using any type of fuel additive which could cause the tip (rubber ?) of the float needle go out of shape? I might replace float needles every few years at most.
1980 kz750E1, Delkevic exhaust
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- koolaid_kid
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I had problems with my aftermarket ones; went back to OEM and the issues went away.
1983 GPz 750
810 Wiseco, Kerker, K&N, DynoJet S3, Accel, Progressive, etc.
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- bountyhunter
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In my experience, it's more often caused by a piece of crud keeping the needle from seating well.astark wrote: Hi, I've been having some issues with the Keihin CV34's on my 1980 KZ750 LTD. One of the carbs keeps leaking gas out of the float bowl. The float height is fine, the float isn't damaged, it appears that the float needle keeps sticking open, allowing gas to flow.
Can you visually inspect the surface that the needle tip seats against? If it is dirty or rough, it won't seat tight and will leak. You may be able to polish it using a tool cut from a popsicle stick. Cut it narrow enough and then angle the tip and use some brass polish to turn it by hand and polish the seating face.
If the tip of the needle is all metal, you can put it in a drill and spin it and polish it smooth with 600 grit paper and oil. If the tip is rubber, just clean it with solvent.
Note: I started using Lucas fuel conditioner and it keeps the carb cleaner because it prevents gas from oxidizing into sticky slime. Might help if you have chronic problems.
1979 KZ-750 Twin
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- astark
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1980 KZ750H LTD
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- bountyhunter
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Is the seat not removable?
If not, be very careful with it.
1979 KZ-750 Twin
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- astark
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1980 KZ750H LTD
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- JR
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Are you sure the float and needle are at fault ? The brass overflow tube in float bowl could have a crack in it - it happens. Happened to me. To check, take the bowl off, put a rubber tube on the overflow nipple, fill bowl with water, put finger over the open end of the brass tube and blow into the rubber tube. Watch for bubbles to pinpoint a leak..
If this is the problem then its an easy fix
JB Weld as long as its allowed to cure properly. or get a slightly wider brass tube from a hobby shop and slip it over the existing brass and solder the bottom.
Check also the drain screw and o ring
Good luck
1980 kz750E1, Delkevic exhaust
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- KZQ
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I fought the same problem as you for a couple of years till I relented and went the clear tube method. What I found was that I had to bend the tang pretty radically till the fuel level would stay 5.5 to 8.5mm below the bowl gasket as the manual specified. This was on my 1300 but you could be having the same problem.
Bill
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Riders:
1968 BSA 441 Shooting Star, 1970 BSA 650 Lightning, 1974 W3, 1976 KZ900, 1979 KZ750 Twin, 1979 KZ750 Twin Trike, 1981 KZ1300, 1982 KZ1100 Spectre, 2000 Valkyrie, 2009 Yamaha Roadliner S. 1983 GL 1100
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1985 ZN1300
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- bountyhunter
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Checked with clear tube?astark wrote: , the float height is good,
You said before there is a rough spot on the seat the needle tip mates with. If so, it will always leak.
1979 KZ-750 Twin
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- koolaid_kid
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1983 GPz 750
810 Wiseco, Kerker, K&N, DynoJet S3, Accel, Progressive, etc.
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- daveo
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koolaid_kid wrote: Are you using OEM float needles? The aftermarket ones are prone to having weak spring structures.
I had problems with my aftermarket ones; went back to OEM and the issues went away.
+1 :ohmy:
1982 KZ1100-A2
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