Why people shut-off petrol valve of bike?

[rzn_880]

It is generally said that when you park your bike for abut 8-12hours, you must shut-off its patrol valve. For example, I have Suzuki 110cc and I park my bike in office stand for about 10-12hours. Should I shut-off the petrol valve? What is the reason for shutting off?

[dammuzi]

Gas can leak out of your carbs if you don't. I have a 33 year old bike, and my girlfriend has a 30 year old bike. My carbs don't leak, but if you leave hers parked on the kick stand with the petcock in the on position, it will start leaking gas out of the carbs after a few hours.

[James]

If either the float or needle valve in the carburetor sticks, gas will flow unimpeded into the carb. This can [1] empty your gas tank onto the ground; [2] make the bike impossible to start; [3] fill the cylinder with gas, possibly causing a bent connecting rod when you try to start the motor. (This occurred occasionally with Honda 6-cylinder CBX's--a very expensive motor to disassemble and repair--among others)