Spitting out gas is unusual, spitting out oil is not. See madnss advice. Sounds like oil blowby from breathers, check oil level properly.
John
he means to keep your oil level low if it is oil... i keep mine below half full - i have a horseshoe breather installed and i can still get some blowby if i over fill. never heard of gas coming out of the breather... no idea how that could happen -
When does the "spitting" happen? If it occurs when you first start the bike, your carb might be getting flooded while sitting parked. I might suggest that you put the petcock in the "off" position when you turn the bike off.