CARBS LEAKING FUEL!!!

[Cal Walker]

Hey, i am new too this forum and regardless to say i need some help,

Ive had my NC30 since august last year and its only been ridden a couple of times in march this year, due too it being a bit of a run and restore project for me and passing my test, its then sat for another 3 months with me stripping it down for a good clean and me fitting a second hand standard exhaust system to her, just finished the exhaust yesterday and fired her up to check for blows/leaks, she started fine and all was dandy then i smelt a distinct smell of petrol and looked under the carbs and they were dripping fuel around the float chambers?? The bike is currently fitted with a 33bhp kit as well.

Is this me, disturbing the engine slightly and it jiggling the carbs while ive been fitting the exhaust? Or have the seals perished in the carbs due it has been used on and off in the few months?? When it has been sat the fuel tap has been turned off, so there would of been no fuel in the carbs i assume.

If anyone could get back to me i would be very grateful!!!

Regards....Cal

[CMSMJ1]

Welcome Cal,

few things to check I reckon

1: does the fuel tap work? If you turn on does it leak? If so, the tap needs rebuilding

2: Carbs - fairly common issue that the float valves can get shit in them or stick - give the carbs a tap.

easy to sort out mate, so don't worry about it

[Cal Walker]

Cheers,

Yeah fuel tap works, fine but i shall check that, also would i need to take the carbs off just too give them a bit of a tap? just was a bit worried when you can see fuel dripping out from there thought all the seals may have gone.

Thankyou for the reply!!

[Cal Walker]

Just been out in the garage with the bike, and no fuel has been dripping over night, turned the fuel tap on and no leaks coming out so the fuel tap is all ok.

Haven't gave the carbs a tap yet or started it up again, has anyone else had this problem before?

If anybody else has any suggestions please feel free

Regards......Cal

[micpec]

You are most probably looking at the need of replacing the seals of the carb float chambers. These need to be perfect in their groove while fitting it up. Remember not to overtighten the float chamber screws as this may cause cracks in the carbs mounting points, use proper tooling for the screws too or you have another issue coming with these screws. Check the condition of each seal before fitting, if in doubt if they are in the correct position I would advice to use little bit of grease in the groove so the seal holds in that position. Either buy new genuine ones (expensive way) or the copied in viton ones (cheaper) via LikeTekBlair or Rick O.

[Cal Walker]

Cheers for your reply,

If i take the carbs off the do the float chamber gaskets, can you do these without having to touch anything else? i.e not altering the carburetor set-up, the last thing i want to do is have to set them all up again. Also are they easy to do?

[Neosophist]

Just been out in the garage with the bike, and no fuel has been dripping over night, turned the fuel tap on and no leaks coming out so the fuel tap is all ok.

Haven't gave the carbs a tap yet or started it up again, has anyone else had this problem before?

If anybody else has any suggestions please feel free

Regards......Cal

Yes, especially if your carbs became empty and then you turned on the fuel (this can happen when fitting overhauled carbs too)

sometimes the float (like in your toilet tank) fails to float and shut off the fuel.. it can get wedged or stuck.

This causes a leak of fuel.. with old carbs its often due to gettting gummed up (sometimes if you leave some fuel to soak in there it will disolve the blockage and will fix itself)

Often tapping the float bowls hard with the handle end of a screwdrive (no need to remove carbs) will disloge the issue and fix the carbs.

For the price of the new carb seal kits from a member on here i would replace the rubbers for piece of mind if you decide to undo them.

[micpec]

Cheers for your reply,

If i take the carbs off the do the float chamber gaskets, can you do these without having to touch anything else? i.e not altering the carburetor set-up, the last thing i want to do is have to set them all up again. Also are they easy to do?

If you do it correct then that is a Yes! It is possible just to do the float chamber themself. Done it last month a couple of time including all new seals too in few hours. Drain any fuel in the chambers, get the carbs off, turn it up-side-down so you can get to all screws, undo the screws, work per chamber, get them back on, and fit your carbs.

About the fuel tap turning to ON modus and check if that is leaking....would that really tell you if a fuel tap is leaking as a normal tap is also vacuum operated. What I mean is is that really the root-cause for this? To me it lies more into your carbs.

[Cal Walker]

Right ok, ill go out tomorrow and give the carbs a slight tap on each float chamber, fire her up and see if fuel is still leaking from around there. If it does still leak, then ill take the carbs off and replace the gasket around each float chamber and hopefully that'll sort it!

Just hoping this is a simple and easy fix!!??

Regards......Cal

[Tornado]

My wife's RVF did the same thing after I removed the bowls to clean up the carbs. I used the original o-ring gaskets and they dripped pretty good for a few minutes then stopped. The only thing I could think of is the gas caused the float bowl o-ring gasket to swell which stopped the leaking. I have since ultrasonically cleaned the carbs and replaced all the o-ring seals with Blairs kit. (Which I highly recommend)