The bike will run no problem without the decomp circuit... starting is the issue. (Joke!) Seriously though, I believe Dr_Jim is right that the bike does want a decomp mechanism. They did so much to make this bike cheap that I believe they would have left it off if they thought they could get away with it.
That sad, I am not running a decomp on this bike at the moment. I know I'm taking a risk. (See below about risk taking...) I've got a brand new strong battery and a light touch on the starter button. Usually the bike just starts on the first revolution. Every once in a while the air in the piston pushes back before the starter has had time to build up enough momentum and I just let it stop and then I try again.
I did consider welding a lever to a socket that would fit over the bolt for the decomp mechanism. Just push down with your thumb, start, let go. Stick the socket in your pocket. I'll do that after I break the case for the first time of course.
But you may not want to follow my example. This is what happens when you demand 50% greater power from your motor but you don't arrange for 50% greater heat dissipation:
I finally have a performance carb to match the performance cam and less restrictive exhaust. So what do I do with it? I break the piston.
I need to take the cylinder off now and find out if I just need a new top end or if I need a whole new engine.
C'est la vie.
Oh, and Islandwahine, the tank holds abut 3 1/2 gallons. It has a big tunnel in it for the Triumph it was really designed for.