Fuel leak underneath bike

If the leak is at the back of the car there are two main areas to check. The fuel tank and the brake system.
Some questions to give you the best help I can. How old is your car? Is it a fast leak or a slow drip? Is it at the edge of the car or further underneath? Please Comment.
You might need to jack up the car and safely support it on axle stands before you take the wheel off on that side.
With the wheel off, check the brake drum or caliper for leaks, then check the pipes coming out of it as they move under the car.
If it is right at the back of the wheel arch it is not very likely to be a fuel leak unless the fuel filler hole is on that side. The fuel moves around as you drive so it might be leaking from the joint from filler to the tank.
This may sound a silly idea but touch the leak and smell it. If it's an oily almost fishy smell it is likely to be brake fluid. you should recognise if it is Diesel.
*Make sure you wash your hands well if you do touch the fluid*

Jackie, It is probably a seal(gasket) leaking, you may want a service tech. to have a look.

if you got a carb then its the overflow pipe from the fuel bowl and the float is stuck or wrong height setting , or fuel feed pipe perished or tank ! try starting then turn fuel off and see if leak stops !

Fuel around the spark plug? I've never seen this before. Usually, if fuel is on the engine, it evaporates very quickly even if the engine is cold. If you notice the fuel there before you start the engine, it's probably leaking from the fuel tank or a hose above the rear cylinder head. It may be leaking somewhere up front and running down the bottom of the tank and dropping off in that area. I can say that it is probably not coming from the engine. Check for a leak in the fuel tank somewhere.

Good Luck
steve

shouldnt be because the fuel is on as that would only leak fuel, degrease it and park it over a white sheet of paper to find out where the oil can be coming from

seems you have a leak somewhere in the fuel system.check all lines for moisture from fuel. Leak could be anywhere between fuek tank and injectors. Check all fuel fittings, could even be a bad seal on fuel filter. An air leak is really hard to find at times. Patience is the key, may not be a real quick fix. Good luck

The bike has a tube coming of the air box that you drain as neded. Additionally you have a 9 year bike and these items build up with miles, and yes age. So be sure to inspect and replace these items per the owners manual. No big deal just part of owning a bike.

The evaporative leak detection diagnostic strategy is based on applying a vacuum to the EVAP system and monitoring the vacuum decay rate. The VCM monitors the vacuum level via the fuel tank pressure sensor input. At an appropriate time, the EVAP purge solenoid and the EVAP vent solenoid turn ON, allowing the engine vacuum to draw a small vacuum on the entire evaporative emission system. If a sufficient vacuum level cannot be achieved, a large leak or an EVAP system malfunction is indicated. The following conditions can cause this problem:
A disconnected or malfunctioning fuel tank pressure sensor.
A missing, malfunctioning, improperly installed, or loose fuel cap.
A disconnected, damaged, pinched, or blocked EVAP purge line.
A disconnected or damaged EVAP vent hose.
A disconnected, damaged, pinched, or blocked fuel tank vapor line.
A disconnected or malfunctioning EVAP purge solenoid.
A disconnected or malfunctioning EVAP vent solenoid.
An open ignition feed circuit to the EVAP vent or purge solenoid.
A damaged EVAP canister.
A leaking fuel sender assembly O-ring.
A leaking fuel tank or fuel filler neck.
Any of the above conditions can set a DTC P0440.

Your may have to drop the tank and check the vent valve, see if it's broke off at the vacuum line fitting since you mentioned that gas las leaking from the tank. 
When checking the vent/purge solenoid, depends on whether you have a 2dr or a 4dr. I can't remember the exact location of the 2dr vent/purge solenoid, but on a 4dr, just drop the spare tire if you have it underneath and it'll be in the middle of the cross member directly behind the rear axle. It'll have one large vacuum line and an electrical connector. 
You can also see the gas filler tube to the rear of the gas tank, check for any damages where the gas may be coming out of.
Good luck and hope this saves you some money, I believe most dealer will charge close to $400.00 to drop the gas tank and do this job.

CARBS ARE FLOODING DID YOU TURN OFF GAS WHEN YOU LEFT THE BIKE STANDING THE PIES YOU ARE TALKING ABOUT ARE THE CRANK AND AIR BOX BREATHERS YOU NEED TO TURN OFF FUEL AND DRAIN THE CARBS KEEP THE BIKE CENTER THEN TURN FUEL BACK ON LEAVE FOR 5 MINS THEN START THE BIKE IT SHOULDNT LEAK ANYMORE

if bike sits on side stand all fluids will drip off the left side check the front sprocket shaft seal that might be the culprit