Since a YS is pumped and uses a one way valve, the tank can go back to the CG without any trouble. I am finishing up on a new project and was wondering......... With a Magnum .91 4c, how far back can I place my tank. This is not a pumped engine, brand new, mounted upright. tHANKS FOR ANY HELP.

The tank should be as close to the engine as you can get it. Fuel lines should also be as short as you can make them and still reach the carb.

You might be able to move it back a couple inches, and
get away withi it....but I'm afraid you might run into
"leaning out" problems.

I used a Perry occilating pump on a Saito once, and it
worked good. I made an aluminum sheet mount, and
bolted it onto the back-plate screws.

Dave.