Prime?

[capnkirk]

Okay, this is probably a stupid question, but I have to ask...

What is this "prime" setting on the petcock? I'd never seen or heard of it until I owned Yamaha.

Now that I think of it, this is also the first bike I've ever had with TWO petcocks. Never seen or heard of this either.

Cap'n

[DiverRay]

The petcocks are Vacuum operated. Prime allows fuel to flow with NO VACUUM. It is the way you get fuel into the carbs after you have rebuilt them, worked on them, or drained them. If you go to xs11.com, and scroll down, you will find all kinds of information about your bike. If you put in the year and model of the bike in your signature, help will be faster when you ask questions. I know a lot about the standards, as I own two, but not about the specials, as I just work on Ed's now and then.

[skids]

There are two petcocks because there is a hump in the bottom of the tank.

Prime is for bypassing the vacuum operated diaphragm. You get vacuum from a running engine. If you want to fill the carb bowls after working on them, use prime. If you want to synch the carbs, you will likely have to use the manifold nipples thereby disconnecting the vacuum lines to the petcocks...you would run the engine on prime during that procedure.