Is it safe to weld a motorcycle with the carbs still on it?

The fire blanket should be enough, I would keep a fire extinguisher handy just for safety.

Hey trev,

Just drain the float bowls and cover up the carbies real good with some wet towels, plug up the end of the fuel lines with some wooden dowel or an old bolt of suitable size, 6mm or 1/4, and then put the welding blanket over the lot and you'll be right. You only get problems with vapour exploding when you weld a fuel tank directly, just welding next to the carbies you won't have any vapour to ignite and the carbies won't get hot.

I would not do it – you are creating too many risks for something to go very wrong.

Presumably you will also be grinding to clean up the surfaces and get a clean contact too (even more opportunity for injury and disaster).

At the very least run the bike with the fuel tank removed until it stops to drain the carbs (if you cannot locate the drains under the float bowl).

Removing/replacing carbs is not difficult – why risk your bike going up in smoke?

The Blanket will work.

Most carbs have a bleeder or drain screw where you can at least empty it .