Do I Need To Adjust My Float Height?
When tuning your carb or carbs, it is important to be detail oriented and pay attention to whats going on. If the float tabs get bent or moved out of place, this can drastically affect how your bike functions and for such a simple part, can cause a LOT of issues!
What the hell is a float and how does it work?
The float does what its name implies, it floats at the top of the fuel in your float bowl, and is attached to a needle that is situated in the float valve. The float needle is rubber tipped and when the float rises the needle is pressed into a V-shaped seat which then stops fuel from coming into the bowl. As the motor-generated vacuum draws fuel up and out of the carb via jets and fuel and air passages, the fuel level in the bowl will drop, thus releasing the float needle from its seat and allowing more fuel to flow into the float bowl.
It can never hurt to check your float height while you have your carbs off for a re-jet or just a cleanup. You want to set the float height so your bike runs on the properly metered amount of fuel it needs.
If the floats are set too high, fuel will overflow via overflow ports that are drilled into the carb body. Even worse, fuel may flow into the engine, which, if the engine is not running, can cause hydraulic lock (hydro-lock) that is, as the piston rises on the compression stroke it cannot compress the liquid form of fuel. This also means you have now "washed" your cylinders, and removed all lubricating film of oil from the cylinder walls. You must flush your engine of all oil as all the oil has now been contaminated with fuel and no longer retains the proper lubrication properties needed to run your motor. If you have leaked gas into your oil, you MUST flush the motor properly, replace your filter, and fill with fresh oil.
What to watch for :
If the float height is too high, this will cause the fuel to rise to a level above the operational spec. If the fuel height is a bit too high and the bike is running, the engine will display a rich running condition, which will make the throttle response slow and the engine note muffled. This condition is usually accompanied by a strong smell of unburnt fuel from the exhaust.
Float level is too low
If the float height is too low, this will cause the fuel to drop to a level below the operational spec. If the fuel height is a bit too low, the engine will display a lean running condition, where the engine hesitates before accelerating or surges as the throttle is opened. The jets are not able to reach fuel as the level is too low, and the float is shutting off the fuel supply before the operational fuel level is reached. The bike may also misfire when the throttle is closed.