Fixing a flooded motorcycle engine is actually quite possible. In most cases, flooding occurs because too much gasoline is allowed into the engine at once. The easiest solution is to just be patient and wait for the gas to evaporate from the internal parts of the engine. However, even if you don't have time to wait around for the gasoline-coated parts to dry, there are some ways to correct the problem of a flooded motor cycle engine within as little as 30 minutes.
Is Your Engine Flooded?
There are many things that will prevent a motorcycle from starting. They are usually grouped into two categories: ignition problems or gasoline problems.
Poor, inconsistent cylinder compression can stem from a prevention of the explosion of the gas/air mixture, improper ignition timing, a failed ignition coil, faulty spark plugs, or mistimed engine valves.
A flooded carburetor or engine could also cause a non-starting condition. When a gasoline engine floods, too much gasoline has been allowed to accumulate within the combustion chamber through choke usage. On a more basic level, the gasoline liquid coats the cylinder walls and dampens the electrodes on the spark plug, making it too wet to ignite a spark within the spark plug's electrode gap.
So, if you are confident the problem is not a part of the electrical system, besides the spark plug, and the smell of gas is present, chances are your system has flooded and the motor needs evaporating or fixing.
Step 1 - Dry Spark Plugs
As stated, your motorcycle's spark plugs are one of the first areas you should check. Using the spark plug wrench, turn each plug counterclockwise and remove it. Be careful not to break the spark plug top.
Check to see if the spark plug is wet. If it is, dry it off as best you can with a cloth. Then, wipe it down with a clean rag. Lay it in the sun after wiping it dry and running some air over it.
In severe cases it may be necessary to replace the spark plugs entirely if they can no longer produce a sufficient spark.
Step 2 - Drain the Excess
Next, turn the gas valve off and turn the choke off on the carburetor. While standing on the side of the bike that contains the carburetor, lay the bike over slightly on its side. This will drain any excess gasoline that may have collected in the carburetor's overflow tubes. Wipe up the gasoline that may drain out with rags.
Step 3 - Dry Compression Cylinders
Kick start the bike with the spark plugs in question removed. You'll want to do so 8-10 times in order to dry the cylinders.
If you do not have a motorcycle that employs a kick start, you may need to manually start the engine via a push start or a bump start. This is achieved by physically pushing the motorcycle quickly and abruptly enough to force the engine into gear. Often times this requires the labor of more than one person pushing the motorcycle.
Step 4 - (Re)Install Spark Plugs
Reinstall the dry spark plug or plugs that you removed, or install new spark plugs. Be certain to gap the spark plugs before you reinstall them in accordance with the manufacturer's specifications.
Step 5 - Start the Motorcycle
With the gas still turned off, and the choke off, kick start the motor. Immediately upon it starting, turn the gas back on. This should solve the problem if it was a flooded engine.
Step 6 - Check the Cylinders
In addition to the engine overall, it's possible for gas to pool inside the bike's cylinders. To check this, pull your oil plug and see if there is gasoline in the oil. If there is, change it. When there is flooding, there is also tiny microscopic debris that gets in the carb and holds the float needles open enough to leak. Clean the carbs, and install an inline fuel filter so this doesn't happen again.
WARNING: Don't run a bike with fuel in the oil, you'll destroy the engine.