What Do I Do If Gas Got Into My Cylinders?
If you got fuel into your cylinders you have begun the process of hydrostatic lock or Hydrolock.
Hydrostatic lock is an abnormal condition of any device which is designed to compress a gas by mechanically restraining it; most commonly the reciprocating internal combustion engine,
Hydrolock occurs when a volume of liquid greater than the volume of the cylinder at its minimum (end of the piston's stroke) enters the cylinder. Since liquids are nearly impossible to compress, the piston cannot complete its travel; either the engine must stop rotating or a mechanical failure must occur. Basically, the fun is over.
What Causes Hydrolock?
In motorcycles this is most commonly caused by the float valve not seating, due to buildup of varnish, or debris such as rust, or corrosion in the fuel. This can also be caused by a cylinder failing to fire, thus accumulating unburnt gas in the combustion chamber ( which is pretty damn noticeable). Hydrolock can also be caused by getting water into the motor but in this article we will approach things from a fuel induced hydrolock.
If a cylinder fills with fuel while the engine is turned off, the engine will most likely refuse to turn when a starting cycle is attempted. Since most bikes starter torque is normally far lower than the engine's operating torque, this will usually not damage the engine but may burn out the starter. The engine can be drained and restarted. If a corrosive substance such as water has been in the engine long enough to cause rusting, more extensive (and expensive) repairs will be required. If the hydrolock occurs while the motor is running, some of the damages that can occur are as follows. You can break a rod, get bent or broken connecting rods, a fractured crank, a fractured head, a fractured block, crankcase damage, damaged bearings, or any combination of these. Forces absorbed by other interconnected components may cause additional damage. Physical destruction to metal parts can sound like a "crashing" or "screeching" or "whining" sound and usually requires replacement of the engine or a substantial rebuild of its major components.
You may see gas coming out of the exhaust, or smell gas very strongly from the exhaust, fuel may be dripping out of the venturi of the carb, you may have fuel leaking past the carb insulator boots, all of these are indicative of a possible hydrolock.
So What Do I Do To Fix It?
If fuel has gotten past the rings and into the oil, you are going to have to flush the lubrication system. Pull the dipstick out of the oil, and if you smell gas, even a hint of gas, you need to purge all the oil. Once fuel starts to get into the cylinder and does not ignite, it begins to strip the wall, and the rings and piston of the VERY thin layer of oil which provides lubrication and protection to the cylinder walls and the piston. The internal surfaces of your motor which desperately need adequate lubrication are now stripped down to bare metal against metal.
First, make sure the reason for fuel getting into the cylinders has been solved, address your float valve, replace or properly clean. Once you know the carbs will not leak fuel into the motor anymore you can proceed.
Drain the oil from the bike, let it sit overnight with the filter and drain plug off to get as much of the oil out as possible.
Install a new filter and replace the plug, fill the motor up with the required volume. Take a dropper and put about a half teaspoon of oil into the cylinders through the spark plug holes. This is to prevent the rings from experiencing a dry start and scraping the cylinder to hell. replace the spark plugs Once you put some oil in the cylinders, lean the bike over to the left for awhile, let the oil move around to the far left side of the cylinders, then tip the bike to the right, then let it sit for awhile. I like to leave a bike for a few hours after putting oil in the cylinders, it allows it to seep into the rings a bit more and reduces the amount of smoke on startup.
Yes your bike will smoke when you turn it over because of the abundance of oil in the cylinders, however, this is normal for the cleanup process.
Turn the bike over a few times slowly by hand, I'd say 5-10 full cycles to spread the oil around, next, start the bike up for a few minutes, let it warm up, then before it cools, drain all the oil out. put a new oil filter on, trash the previous one, and refill the motor with the proper volume of oil and you are ready to go.
I know its a total bitch but unless you want to spend a lot of money on repairs, if a bike is hydrolocked or on its way, , clean it up and do it right!