Petcock Settings

Hi All.. My 81 KZ650 is almost on the road. I know that my petcock has no off position because it is vacuume actuated. However what is the difference between settings on and primary. reserve is obvious. But isn't on and primary the same thing?

The prime setting is used to fill your carb bowls after service. When the petcock is in this setting the gas just flows.If you had a stuck carb float and left the petcock in the prime position you'd soon have a mess on the floor. The on setting will only flow gas when a vacuum is applied and should be used when the bike is running. You can leave it this position and not worry about flooding out your carbs. Hope this helps.

Al