Quick Carb Overflow fixes

Correctly servicing the Carburettors on these bikes is paramount to good running and fuel economy so any work done will pay back in better mileage :)
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Quick Carb Overflow fixes

Postby Gman » Tue Feb 15, 2011 11:34 pm

Sometimes the Carbs and Carb overflows may drip.Depending on the position of the bike/engine valves etc when stopped/stood for any length of time this can cause fuel to go back onto the Air filter housing and in rare cases if all things being wrong let fuel enter the engine and into the oil.I know because I've had this happen one time.

Also after the bikes are laid up sometimes moisture can get into the float bowls via condensation.Some people drain their carbs when,"Winterizing".I don't think this is a good idea as it allows more bare surface area for Alloy corrosion inside the bowls to occur.Better to add a fuel stabilizer/additive like Seafoam or any cheap fuel treatment from the supermarket/car shop.

A correctly operating Vacuum petcock will prevent this but read below anyway.



To this end it's safest to switch the petcock/fuel tap off when stopped.I've painted my Petcock lever Red on top when in the Off position.This reminds me to switch it back on.

Quick fixes.

1:Tap the sides of the carbs lightly with a small hammer or similar in the hope it will free the FNV(Float Needle Valve).If this may cure it if you take the bike for a run.

2:Place container under the rear wheel where the two overflow pipes from the carbs come down to catch fuel.
Petcock off.
Slack off the two large drain screws in the Carbs.The left hand side one is easy to get to the right hand side one will require a long necked flat blade screwdriver.If these screws will not release you should take the carbs off and free them.These two screws are often overlooked in Carb maintenance but are important.

This will allow fuel to drain from the carbs.Tighten right hand side and switch petcock on and let some more fuel flow through into the receptacle.Switch petcock off and tighten left side and slack off right hand side and repeat.Once done make sure petcock is off and both screws are secure but don't over-tighten them.
With luck this will have let the floats and FNVs drop and the fuel flowing through may have cleared any grit in the FNV holes preventing the Floats and FNVs operating.
If not you will need to take the carbs off to fully service them and see other sections on setting the correct float heights.

If there is ANY fuel smell in the engine oil replace the engine oil.
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Gman
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Location: Hull.Yorkshire.UK.2x1980 CX500ZABs:Citroen ZX TD(250,000 miles)

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