Flooding carb

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Jul 18, 2004
Hey Folks,

Finally have the bike on the road - all legal like, goes like a bat out of hell. Y esterday I bought gas and now I have a flooding right carb.
I pulled the float bowl off and all seems fine (viton needle, new gasket, no leaks in the float), could this be caused by a this a plugged pilot circuit?

It was working fine until I filled up at the gas station. My petcocks have filters, the banjos have filters - I can't imagine debris getting in... any thoughts before I pull the carb off and probe every orifice. :shock:

And so begins life with Norton....

Sounds like a float height problem. I'd start by rechecking to see that the float height is not set too high.
Thanks, hadn't thought to check.
My first thought was a problem with the float needle coming off the float, but it was ok. I suppose the bowl could expand and the seat move - but the bike was barely warm, and it was running fine... now it drips and comes out of the tickler... tickler is free...
I swapped bowls and the flooding is now intermittent on the other side - so it is definitely a problem with the float. I checked the float levels and they are fine. I think the gasket must be the problem. I will trim the inner bits off and let you know if that does the trick.
Thanks for the suggestions.
i had the same problem myself after removing one of the float bowls. The gasket seemed to foul the float causing the carb to flood, cutting the gasket back in the area of the float pivot pin cured the problem for me.
Hope this helps.
If it floods through the tickler the float is probably gas logged. A problem in the pilot circuit will cause a backfire on the overrun (when you've let off the throttle and the bike is backing down).
I found when I struggled with the Amals on the 850 , that ideally one should cut the right angle protrusion on the gasket, just slightly where the float mount pin sits.

It is a bit hard to describe this but looking at the gasket mounted on the fuel bowl and float in situ you can see what I am suggesting.

I think you have a problem with the float and or needle being slightly obstructed, thus causing flooding.
Thanks for the input.

The bike has been running just great this week, no more flooding (it just went away.
I just went to the gas station this afternoon and filled the tank. Now I have the flooding issue again. Interesting that it only occurs with a full tank. Not sure what to make of that.
I will trim the gasket (right now) and see if that helps.
I checked the gaskets, swapped, the gaskets, bowls, floats, and have narrowed it down to the needle. I tried using an old plastic needle and gas just pours through like a sieve! I drained half the tank and it seems better.

I guess one needle tip is misshapen? I will swap the float needles again just to make sure that is it, and order a new viton.

I suspect that the reason for flooding when the tank is full is that there is increased weight / pressure on the fuel system,perhaps enough to lift the whole float and needle assembly off the seat?. Good luck. Ride safely. James.
The weight of the gas and the push that it asserts on the float needle are certainly at fault here...but there is an underlying reason why the float needle isn't sealing and the gas comes on through.
Either the needle isn't being pushed up in the seat with enough pressure to overcome the pressure of the gas it should be holding back, or the needle/seat is faulty. Recheck the float level, the needle and the float itself. Really old floats will also have wear at the point where the tiny brass hinge pin goes through them and this will cause the float to not get the leverage it should. Brass pin can be worn too, and even the slot in the bowl that holds the pin can be trashed and all gets just too floppy to push on the needle and seal the gas out...you said the problem changed sides when you changed the bowl around...check all for too much play and recheck the float level and needle/seat. Grin! You will find it, and when you do, it will all seem so simple...
Well it seems that the problem was the float seat.
The surface as ever so sligtly off, and I mean slightly - but pehaps because of the vibrations on the engine this is enough to shake it loose and allow gas to sneak by the needle.
So there you have it. Mystery solved!

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