I have a 98 f3 carbs have been cleaned no exposed wires no gas leaks but when it warms up it catches fire I don't know why this is happening could someone please help

 

Where does it "catch fire" - you need to explain your problem better.

 

it's around the carbs but it doesn't seem to be backfireing through them it idles and runs fine till it catches fire

 

They must be leaking gas then - there's no other explanation.

 

Did you replace all rubbers in carbs? Float-bowl seals, float valves, pilot-screw O-rings, fuel-rail O-rings?

There are fluorescent dyes you can get to put into tank. Then use UV flashlight or fluorescent bulbs (not incandescent party light), that will make leaks glow bright green to show where it's coming out.