A month ago i bought my first bike a yamaha Seca xs400. The guy told me when i bought it he had the carbs completely rebuilt, new battery, new spark plugs, and flushed out the gas tank due to it not starting. When i bought it it seemed it ran and started just fine until i got it home it was just really cold blooded i thought(Full choke only) but it always started at least the first couple times. The past two weeks i've been having a hard time getting it started. I charged the battery and tested it to make sure that wasn't it. There is plenty of gas in the tank. I pulled out the spark plugs, and one of them was pretty wet with gas and the other not so much. I cleaned them both anyway and still same results. One strange thing is one day it wouldn't start so i poured .5 gallon of gas in and it started right up, it had 2 gallons in at that time. Also if i leave my petcock in the ON position, a little gas leaks out after a few days. I noticed today that if i push my petcock to any of the three settings that i never see any fuel enter the carb through the clear rubber hose. Is my petcock bad? the bike idles and drives great when i get it started