Overflowing tickler

Hi, 

Whilst the tickler should be spring loaded, there isn't a seal on it ( well on my 389's there isn't) as that is where the paint stripper, sorry petrol comes out of when you tickle it.

If you have petrol flowing out of it, then the float/float needle isn't doing its job, possibly due to debris from the tank going through the tap and holding the float needle off its seat.

Could also be the float is not as buoyant as it should be or it is binding on the body/float cover? Again, my 389's with the 'stayup' float needed a 2nd gasket between the body and cover for it to work.

If there is any rust inside the tank, any deterioration of the tap or fuel lines or filters, then particles WILL find their way into the carb.

Note: If the tank was lined in 1994, eg. Petseal,  then 99% of modern fuels will destroy it and you will get a blocked carb. Only solution to that is to chemically remove the liner and start again.

Best wishes on the rebuild,

George. 

... that the brass spacer on the outer end of the float spindle is present as it's very easily lost and the float then hangs up. I would buy a new viton tipped float needle anyway as previous types often leak.

In my youth it was not uncommon that monoblocs sometimes leaked. Solved with a not too gentle hand hit on the carburettor. The shock probably aligned the float needle. Did work last year on a B44 too. Of course replacing some parts is a more permanent solution.

Usually when you suspect a carb issue, it's an ignition problem. When you suspect ignition, it's a carb problem. Using a spray can of starting fluid can give a hint. Another old trick was to warm the spark plug on a stove, but that worked best on singles. But it can be other things e.g. wrong valve tappet clearance.

The hole in the cap is a permanent breather, put some tape over and see how the house smells a few days later. If the tape confirms its the cap breather then use tape when in the garage, if you forget to take the tape off before riding you will not get far. 

If you move the machine around you can create a pressure of petrol vapour in the tank ,so its a good idea to remove the tape till it settles. Same thing if there is a sudden  large temperature variation.  I also tape over to avoid moisture gathering in the tank over winter.

... I've never had any smell of petrol from the breather in a tank cap of any bike I've had in 60 years. Or maybe my sense of smell has been diminished over the years.....

.... with Ian S.  My garage is full of bikes and doesn't smell of petrol.  That is until a leak develops as happened recently with an ancient "Petroflex" pipe that was clearly past its sell by date.

If the smell persists I would be looking for leaks rather than blocking the tank vent.

I'd be looking for vapour paths from garage to house before anything else. And I don't even like candles on the mantelpiece.  Some of my bikes sometimes smell. I like to empty the float chambers before leaving them (although often don't).  I don't rely on the float sealing for a long time without turning off the tap.  Small leaks can often be sealed by rubbing them with a bar of soap. Handy to know in an emergency.

... remember that there should not be a fibre sealing ring between the needle valve housing and the carb body. Modern monoblocs do have one but not originals.