Yamaha 400 special 1980. Where should the petcock lever be when bike is turned off?

[Heather R]

My husband got this bike a couple weeks ago and we have no idea where the lever should be. The 3 choices are res (reserve), On, and pri (prime).
We have the workshop manual but not the owner's and all it tells us is how to rebuild or put together everything.
Any help will be greatly appreciated.

Also if you know how to push start it? We need step-**-step instructions (The thing keeps getting it's engine flooded so I think we're setting the lever wrong (to pri?) when we turn it off.)
Unfortunately neither of us is very skilled with engines. He is planning on taking a course is small engine repair but that's not happening yet.

Again thanks in advance.