Hi : I read your “engine clinic ” articles all the time and enjoy them. My question is this. I was given an O.S. .70 4 stroke “Ultimate:” as a gift. I would never have bought a pumped engine but I’m stuck with this one. I’ve been running 4 strokes for the past 20 years a love em’ but have no experience with a pumper. I have a new model almost ready to go & all the necessary “plumbing” installed to give this “Pumper” what it requires including the “T” necessary to fill
the tank. My question to you is this: Can I ignore all those nipples on the backplate (4) and simply plumb the fuel tank directly into the carb and direct muffler back pressure into the tank as I do with my Saito .80 and O.S. 1.20.?? In other words, can I run this “jewel” as though it were not a pumped engine..?? Will appreciate your thoughts on this and keep those great articles coming. –Ed
Yes, you can bypass the pump and use muffler pressure. However, the pumped engine usually have a larger carburetor throat. If you experience any leaning problems during maneuvers, then it would be best to connect up the pump.