NC30 vacuum hose fuel tap

[Doody090]

Hi on removal of fuel tank I noticed there was no vacuum pipe, I can see where it goes on the tap but where does the other end go please
Cheers

[NGneer]

The vacuum pipe should go from the fuel tap to the nipple on the front of the No3 cylinder (rear right). Nipple is just underneath where the carbs fit.

If your bike runs without this pipe fitted it would indicate the diaphragm, that the vacuum operates, has been removed from your fuel tap. This is not a big problem but remember to turn your fuel tap off every time you stop somewhere as if the floats in your carbs are not 100% at shutting of the fuel flow, fuel could weep past, into the cylinders, past the pistons and mix with your oil in the crank case = not good.

[Yakama]

As happened to me at Cadwell! Not good thankfully I realised before any damage was done

[Doody090]

Thanks, Ive just started restoring and noticed it wasn’t there when I removed the tank. I will strip fuel tap down and check.

[NGneer]

Thanks, Ive just started restoring and noticed it wasn’t there when I removed the tank. I will strip fuel tap down and check.

You don't need to strip the tap to check it.
If the tank has some fuel in it just turn the tap on and see if fuel flows out. If so the diaphragm has been removed or is split. Not the end of the world, but see posts above.

If no fuel flows when you open the tap put a piece of tubing onto the correct nipple on the fuel tap and suck (lightly) on the other end of the tube. If the fuel tap is still complete and working this will simulate the vacuum created by the engine, move the diaphragm over and allow fuel to flow. Stop sucking and the fuel should stop flowing