Gas dripping onto the exhaust from the carbs

Gasoline Autoignition Temperature is a little under 550°F.

The mufler probable is Not that hot.

The Exhaust pipes very near the heads when the engine is under power and the EGTs easily exceed 1000°F might be a different story.

If it is an occasional drip, it probably dances off the pipe like a drop of water in a frying pan, Boiling (~400°F) but never actually heating up any further before getting blown to the wind.

If you have gasoline leaking around hot exhaust pipes, you are already overdue for a repair.

Otherwise you are just "Playing with Fire!" (Pun Intended!) 

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An Oldie but Goodie Video.

Notice that no Flame was needed to start the fire.

Common Carburetor Fuel Leaks. One of the more common problem we get concerns either the overwhelming smell of gas coming from the carburetor or fuel leaking out of the bowl or overflow. Both conditions are typically caused by a stuck or worn float needle valve.

Also weight the Floats in dry conditions not more than 7.0 g. As well as gasket may be displace.Replace it.

and case of Fire hazardous :

 Even Gas dripping on a hot exhaust manifold doesn't make it ignite. ... If the exhaust becomes really hot under hard run up, it may be enough for the gas to catch fire. Fuel leak can pose multiple safety risks.

i suggest: Fit some header wrap cloth to your exhaust in a cowled installation - obviously not necessary on an open installation on a trike. This will also go a long way to preserving all your hosing and wiring.

They are not just drip trays with a line to safely drain fuel away from engine compartment. They are heat shields to keep fuel from boiling in carburetor and this information comes from a Rotax training class.

Yep I have experienced one of the 2 brass pins which guide the floats within the carbies dislodge within the bowl during flight. Was flying in an ELA gyrocopter with a 912 uls at the time. Despite a solid 2mm stream of fuel being directed straight onto the hot exhaust pipe there was no fire. And more amazingly despite the strong smell of fuel there was no drop in the fuel pressure or drop in engine revs.

So on landing we just unclipped the bowl, replaced the pin in the hole (which goes all the way through the base of the bowl) and gave it a wack with the back of a screw driver to get it to reseat within the bowl. This repair was done on a remote uninhabited strip in the middle of Australia and is still in use some 4 years later.

Regards.........Chook.

Yes the first thing with any carb problem is I pull the carb bowls, look at the fuel level for proper height and measure the float weight. All good. Yes we grounded the aircraft, tried to figure out where the fuel was coming from. It had been sitting for 2 years and we got about 15 hours on it when we noticed the fuel drip. Disassembled the carbs and put them back together and no leaks. Suspect rubber seals were dried out and Needed to be reset. Have carb rebuild kit coming in today and if it continues will use it otherwise have a spare. Thanks all for the insite.